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Health News from NHS Choices

Constantly updated health news across a range of subjects.

NHS Choices News

  • BMI tests 'miss' over a quarter of obese children

    "Quarter of obese children missed by BMI tests," the Mail Online reports.

    The headline was prompted by a review that combined the results of 37 studies in more than 50,000 children and found body mass index (BMI) is an imperfect way of detecting excess body fat.

    The study estimated more than a quarter of children (27%) with excess body fat might not be classified as obese when using BMI measurements alone.

    This may mean the missed children don't get the same support to achieve a healthy weight as those correctly identified as obese, and so remain at a higher risk of developing a range of weight-related diseases, such as type 2 diabetes.

    BMI has long been known to be a relatively blunt tool in terms of accurately assessing body fat, as demonstrated in a similar study in 2012. However, this latest study puts a specific figure on the imperfection.

    That said, BMI remains a very useful tool. It provides a reasonably accurate method to estimate obesity rates at a population level, taking just minutes to complete.

    Other methods can be more resource and time consuming (hydrostatic weighing), or can have large margins of error if not done correctly (skin callipers).

    Overall, this study adds to the evidence of BMI's "bluntness" by quantifying the possible impact of the inaccuracy.

    If you are worried about your child's weight, contact your GP. They should be able to make a more detailed assessment.

     

    Where did the story come from?

    The study was carried out by researchers from the US and Czech Republic. No funding source was reported.

    It was published in the peer-reviewed medical journal, Pediatric Obesity.

    The Mail Online's coverage was broadly accurate, though if we were being really pedantic we would point out to the headline writers that 27% is not the same as 25%.

     

    What kind of research was this?

    This was a systematic review and meta-analysis of studies assessing the diagnostic performance of BMI to detect excess fat in children up to the age of 18.

    systematic review seeks to identify and pool the results of all published material on a specific topic, and is an effective way of summarising lots of research evidence. A meta-analysis is a related statistical exercise, where the results of studies are pooled. 

    Excess fat in people raises the risk of many weight-related diseases, such as diabetes and heart disease. Detecting excess fat in children helps identify those most at risk of damaging their health.

    The researchers point out the ideal way of identifying obesity in children and adolescents has not been determined, although BMI is the most widely used screening tool.

    This involves weighing and measuring the height of a young person to estimate their BMI. The BMI is then compared against standard cut-offs, which categorises the person as either underweight, a healthy weight, overweight or obese.

    In England, this is the approach adopted by the NHS National Child Measurement Programme.

     

    What did the research involve?

    The researchers searched electronic medical databases for studies assessing the performance of BMI measurement compared with other measures of body fat in people less than 18 years of age.

    They then pooled the individual study findings using a meta-analysis to give an overall estimate of how well BMI identified people with excess body fat.

    All of the studies included had to compare measuring body fat using BMI with a different reference method, such as DEXA.

    Study authors of relevant articles published on the topic were contacted to source additional relevant literature and supplement the electronic database searches.

    The main analysis reported the sensitivity and specificity of using BMI to detect excess fat in males and females.

    The analysis explored variation between the studies with regard to differences as a result of race, BMI cut-off, BMI reference criteria, and the reference standard for assessing fatness.

     

    What were the basic results?

    The analysis included 37 studies involving 53,521 patients. The average age in the studies ranged from 4 to 18 years.

    The main finding was that commonly used BMI cut-offs showed a pooled sensitivity to detect high fatness of 0.73 (95% confidence interval [CI] 0.67 to 0.79) and a specificity of 0.93 (95% CI 0.88 to 0.96).

    This means that BMI correctly identified children with high fat levels 73% of the time, and correctly identified children without high fat levels 93% of the time.

    On the flip side, this means up to 27% (100% minus 73%) of children with high fat levels were not correctly identified using BMI, so 27% was the false positive rate.

    There was moderate variation in the pooled results as a result of the confounders mentioned above.

     

    How did the researchers interpret the results?

    These results led the researchers to conclude that, "BMI has high specificity but low sensitivity to detect excess adiposity [body fatness] and fails to identify over a quarter of children with excess body fat percentage."

     

    Conclusion

    This systematic review and meta-analysis showed using BMI to detect excess body fat in children up to the age of 18 was not perfect. It estimated more than a quarter of children with excess body fat might not be classed as obese using BMI measurements alone.

    This may mean they don't get the same help and support to achieve a healthy weight as those correctly identified, and so remain at a higher risk of developing a range of weight-related diseases.

    BMI is known to be a far from perfect measure of body fatness, but is often a useful start, so the main conclusion of the research will be nothing new to many health professionals.

    However, this study has put a specific figure on the imperfection: more than 25% are incorrectly given the all-clear when their weight may be harming their health.

    England's current screening of children for excess body fat, the National Child Measurement Programme, uses BMI as its main measure, so this is very relevant to England's youth.

    The way excess body fatness is assessed in this programme is regularly assessed, and this study may contribute to the evidence base considered at the next review of the methodology.

    Measuring body fat in children on a large scale is a challenge, and the best way to do this is likely to be balancing accuracy with pragmatism. Some measures of body fat are time consuming to perform and, in the context of a busy school environment, this may be influential.

    Overall, this study raises a known issue with using BMI to assess body fat in children, but adds to the evidence by quantifying the possible impact of the inaccuracy.

    If you have any concerns about your child's weight, your GP will be able to assess whether their weight may be affecting their health and can offer help and support.

    Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

    Links To The Headlines

    Quarter of obese children missed by BMI tests could be at risk of diabetes and heart disease, scientists warn. Mail Online, October 17 2014

    Links To Science

    Javed A, Jumean M, Murad MH, et al. Diagnostic performance of body mass index to identify obesity as defined by body adiposity in children and adolescents: a systematic review and meta-analysis. Pediatric Obesity. Published online June 24 2014



  • Viagra could double up as heart failure drug

    "Sex pill Viagra could help men suffering from heart disease," reports the Mirror. This headline follows a new review into the potential heart benefits of the active ingredient in erectile dysfunction drugs such as sildenafil (Viagra), called phosphodiesterase type-5 inhibitors (PDE5is).

    PDE5is work by helping blood vessels dilate, which in the case of erectile dysfunction increases blood flow to the penis.

    Researchers were interested in whether this dilation effect could have benefits for certain heart conditions, such as heart failure, where the heart struggles to pump blood because of previous damage to heart muscles.

    They pooled the findings of 24 randomised controlled trials (RCTs), which suggested PDE5is were better than placebos at improving some measures of heart function in men with early signs of heart disease. 

    Commonly reported side effects included flushing, skin rashes and headaches.

    Importantly, the study did not assess the drugs' effects on the heart versus treatments currently available to treat or prevent heart conditions.

    This means we that cannot say whether they are safer or more effective than existing drugs. PDE5is are currently unlicensed for the treatment of heart failure.

     

    Where did the story come from?

    The study was carried out by researchers from Sapienza University of Rome and was funded by a Ministry of Research Grant.

    It was published in the peer-reviewed medical journal BioMed Central. This is an open access journal, so the study is free to read online.

    Generally, the media reported the story accurately. The Mirror, for example, chose its words carefully in saying that, "The sex pill could help men suffering from heart disease". Using the word "could", rather than "does" or "would", adds a necessary element of uncertainty.

    The Mirror's reporting of the study was of a reasonable quality, and included relevant quotes from the study's lead author and a useful explanation of a subtype of heart disease known as left ventricular hypertrophy. In many ways, the paper has put its "posher" broadsheet rivals to shame with its reporting.

     

    What kind of research was this?

    This was a systematic review and meta-analysis of RCTs to assess the effects of the group of drugs known as PDE5i on heart health and function.

    These drugs are currently licensed to treat erectile dysfunction, and include sildenafil, which carries the widely known brand name Viagra.

    PDE5is work by helping blood vessels relax and dilate, increasing blood flow through the vessels.

    This effect also lowers blood pressure, so these drugs are currently contraindicated or used with caution in people with heart disease, including those who have had recent strokes or heart attacks, as the effects are unknown.

    However, various research studies have continued to investigate the possibility these drugs could have a beneficial effect on heart function. This review has looked into their effect on cardiovascular outcomes further.

    A systematic review of RCTs is one of the most robust study designs aimed at proving whether something works or does not work. It can also tell us whether there is simply not enough evidence to tell one way or the other.

     

    What did the research involve?

    The research team searched online medical research databases for placebo-controlled RCTs evaluating the effectiveness and safety of PDE5i for a range of heart-related measures.

    They then pooled the results of a number of RCTs to create combined estimates of the effects of PDE5is in different people with different heart characteristics.

    Some of the main measures they looked at to test if PDE5is improve heart health were:

    • cardiac mass and structure – abnormally high mass can impair the function of the heart
    • cardiac performance
    • afterload – the force developed in the wall of the left ventricle (the large heart chamber that pumps blood to the rest of the body) during blood ejection
    • endothelial function – the endothelium is the inner lining of blood vessels
    • heart rate and blood pressure

    RCT results were divided into a number of subgroups to compare:

    • people with moderate-severe left ventricular hypertrophy (LVH) versus those without – LVH is where the wall of the left ventricle is enlarged and thickened, meaning it is under strain and can't pump as effectively; this is often an early sign of heart disease caused by high blood pressure
    • left versus right heart disease (damage to the left or right ventricles of the heart)
    • cardiac disease versus non-cardiac disease (conditions not directly related to the heart that can impact on heart functions, such as anaemia or kidney disease)
    • age – 60 and under, versus over 60

    All studies were RCTs, double-blind and placebo-controlled. Four studies were crossovers with variable washout periods (a period during a clinical trial where no treatment is given, allowing the effects of previously administered drugs to be "washed out" of the body).

    14 trials received funding from the pharmaceutical companies Pfizer and Eli Lilly or foundations.

    The main analysis compared the results of PDE5i with a placebo across the different subgroups and combined overall.

     

    What were the basic results?

    The searches returned 24 relevant RCTs containing 1,622 participants – 954 randomised to PDE5i and 772 to placebo.

    The main results favoured PDE5i compared with placebo across a range of heart outcomes. Sustained PDE5 inhibition produced:

    • an anti-remodelling effect by reducing cardiac mass (−12.21 g/m2, 95% confidence interval [CI] −18.85, −5.57) in people with left ventricular hypertrophy, and by increasing end-diastolic volume (volume after heart filling: 5.00 mL/m2, 95% CI 3.29, 6.71) in people without LVH
    • an improvement in cardiac performance by increasing cardiac index (0.30 L/min/m2, 95% CI 0.202, 0.406) and ejection fraction (3.56%, 95% CI 1.79, 5.33) – both measures related to how much blood is ejected into the body's circulation
    • no changes in afterload
    • an improvement in flow-mediated vasodilation (3.31%, 95% CI 0.53, 6.08)

    The commonest side effects were those known to be associated with PDE5i, such as flushing, headache, nosebleeds and gastric symptoms.

     

    How did the researchers interpret the results?

    The researchers concluded that, "PDE5i could be reasonably offered to men with cardiac hypertrophy [enlarged heart muscle] and early-stage heart failure.

    "Given the limited gender data, a larger trial on the sex-specific response to long-term PDE5i treatment is required."

     

    Conclusion

    This systematic review of 24 RCTs indicated PDE5is were more effective than placebos at improving specific measures of heart health and were broadly safe.

    PDE5is lower blood pressure, so these drugs are currently contraindicated or used with caution in people with cardiovascular disease, including those with low blood pressure and a history of stroke or heart attack, as the effects are unknown.

    However, various research studies have continued to investigate the possibility that these drugs could have a beneficial effect on heart function.

    This review has looked into their effect on cardiovascular outcomes further and found some promising results, including that they could be beneficial in people with left ventricular enlargement and high blood pressure.

    But the study has only compared PDE5is with placebos, and has not assessed their effects against heart treatments currently available to treat or prevent heart conditions.

    Similarly, the studies included varied in terms of:

    • daily dosage of PDE5i
    • length of treatment – from 4-week to 12-month study periods
    • endpoint assessment method
    • age
    • baseline cardiovascular status
    • gender – 8 trials enrolled only males and 16 trials had a mixed population of 540 females and 459 males

    Pooling such diverse studies may have papered over some of the cracks and nuances in treatment efficacy and safety. For example, these drugs may work much better in some groups than others, or be less safe in some groups compared with others.

    The studies provided a range of clinical data, such as changes in cardiac mass and flow-mediated vasodilation. But it is not clear what impact these measurements would actually have in terms of developing lower levels of heart disease, improving quality of life or extending disease-free life.

    Most of the research was in men, so the knowledge about the effects of PDE5i in women are less clear.

    Overall, the review suggests PDE5is are better than placebo for improving some measures of heart function, but the clinical implications of these findings are currently unclear.

    Despite the review's conclusions that these drugs could have a good safety profile for use in people with certain heart conditions, more research looking at this specific issue is needed.

    These interesting findings prompt the need for further research and, for the time being, the current prescribing information, which advises the cautious prescribing of PDE5i in people with existing cardiovascular conditions, is likely to remain in place.   

    Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

    Links To The Headlines

    Forget sex, Viagra could be used for heart disease. The Times, October 20 2014

    How Viagra could help halt heart attacks and strokes, with some doctors saying it should be routinely prescribed. Mail Online, October 20 2014

    Sex pill Viagra could help men suffering from heart disease, a study has revealed. Daily Mirror, October 20 2014

    Viagra could soon be used for heart disease patients: researchers. The Daily Telegraph, October 20 2014

    Links To Science

    Giannetta E, Feola T, Gianfrilli D, et al. Is chronic inhibition of phosphodiesterase type 5 cardioprotective and safe? A meta-analysis of randomized controlled trials. BMC Medicine. Published online October 20 2014



  • Vegetative patients show awareness during scans

    "Vegetative patients may be more conscious of the world than we think," The Independent reports. Electrodes have detected what has been described as "well-preserved" networks of brain activity in patients in a vegetative state.

    A vegetative state is when a person is awake and may have some basic motor reflexes, but no signs of awareness. It is one of a group of conditions known as disorders of consciousness and often develops after a severe head injury.

    This study performed electroencephalogram (EEG) examinations to study the electrical signals and connections in the brains of 32 people with disorders of consciousness, comparing them with 26 healthy adults.

    The researchers demonstrated that the networks of electrical connections thought to support awareness are impaired in people with disorders of consciousness. They also found the quality of people's brain connections correlates with their level of awareness.

    Most interestingly, they also found a small number of people in a vegetative state may have more conscious awareness than it seems.

    Four people in this state were found to show some signs of "hidden awareness" – they demonstrated brain activity on functional MRI scans when asked to imagine playing tennis (in neurological circles, this is known as the tennis test).

    When looking at the EEG results, the researchers found some of the brain connections that support consciousness in healthy adults were also well preserved in these people.

    The researchers suggest these results may help improve clinical assessments in the future, as well as help identify people who may still have some level of conscious awareness, despite not being able to demonstrate this.

     

    Where did the story come from?

    The study was carried out by researchers from the University of Cambridge, the University of California, the University of Western Ontario, and the Universidad Diego Portales, Chile.

    Funding was provided by various sources, including the Wellcome Trust, the UK Medical Research Council, and the National Institute for Health Research.

    It was published in the peer-reviewed journal, PLOS Computational Biology, which is open access, so the study is available to read online for free.

    The Independent and BBC News reported the study accurately. However, while the sentiment of the Daily Express' headline, "Talking to vegetative state patients can help recovery", may be well intentioned, it does not have a strong foundation.

    Although the study found a small number of people in a vegetative state did seem to have some conscious awareness, despite this not being apparent, it did not look at their brain activity in response to friends and family talking to them. And it certainly has not examined whether this may or may not help them recover.

     

    What kind of research was this?

    This was a case control study that looked at electrical signals coming from the brains of people with disorders of consciousness, and compared them with normal healthy controls.

    There are three conditions that generally fall into what are termed disorders of consciousness, which usually occur after a severe brain injury.

    A minimally conscious state is where the person has very little consciousness, but demonstrates some variable response or awareness of their surroundings.

    A vegetative state is the middle condition, where the person has no environmental awareness at all, but they still demonstrate a sleep-wake cycle and reflexive responses (such as to pain or sound).

    A person in a coma is unconscious, with no awareness at all, does not respond to their environment, and has no sleep-wake cycle and no normal reflex responses.

    This study aimed to further understand the distinctive brain networks that characterise the different disorders of consciousness.

     

    What did the research involve?

    This study took bedside EEG recordings of the electrical signals coming from the brains of 32 people with disorders of consciousness, as well as 26 healthy controls.

    They looked at the amplitude of oscillations and then looked at the structure of brain networks connected by these oscillations.

    The researchers then compared the electrical patterns and connections between the people with disorders of consciousness and the healthy controls.

    They also examined what signalling abnormalities are present in people with disorders of consciousness, to what extent these patterns are consistent across patients, and how the patterns correlate with the level of behavioural response present.

     

    What were the basic results?

    The results of this study are quite complex, reporting the intricate differences in brain networks and connectivity between people with disorders of consciousness and healthy controls.

    In general, the researchers found distinct differences in people with disorders of consciousness compared with the healthy controls.

    They also found the quality of signalling networks in people with disorders of consciousness correlated with the degree of behavioural response they demonstrated.

    Of the people in a vegetative state – who by definition have no behavioural responses – four out of 13 were surprisingly found to demonstrate some signs of brain activity when asked to imagine playing tennis while having their brain scanned by functional MRI scan.

    When looking at the EEGs of this small number of vegetative patients with some signs of "hidden awareness", the researchers found they had well-preserved signalling networks similar to those of healthy adults.

     

    How did the researchers interpret the results?

    The researchers concluded that their findings "inform current understanding of disorders of consciousness by highlighting the distinctive brain networks that characterise them".

    They say tests in a minority of people in a vegetative state indicate signalling pathways that could support mental function and consciousness, although these people have profound behavioural impairment.

     

    Conclusion

    This study performed EEG examinations to study the electrical signals and connections in the brains of 32 people with disorders of consciousness, comparing them with 26 healthy adults.

    The researchers demonstrated the network of electrical connections that support awareness, and how these connections are impaired in people with disorders of consciousness. They also found the quality of people's brain connections correlates with their level of awareness.

    Of most interest, they found a small number of people in a vegetative state may have more conscious awareness than it seems.

    A vegetative state is characterised by a person maintaining spontaneous reflexes, such as to pain or sound, and having a normal sleep-wake cycle, but they cannot demonstrate behavioural responses or conscious awareness of their surroundings.

    But in this study, four people in this state were found to show some signs of hidden awareness – they demonstrated brain activity on a functional MRI scan when asked to imagine playing tennis.

    When looking at their EEGs, the researchers found some of the brain connections that support consciousness in healthy adults were also well preserved in these people, too.

    The researchers suggest the distinct brain network connections seen in people with disorders of consciousness that they have identified in this study may help improve clinical assessments in the future.

    This information may also help identify people who may still have some level of conscious awareness, despite not being able to demonstrate this.

    Further research building on these findings is awaited. Despite one newspaper's report to the contrary, the results of this study are not suddenly going to lead to new treatments for disorders of consciousness – at least in the short term. But learning more about the relationship between brain activities and levels of awareness is always valuable.

    Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

    Links To The Headlines

    Vegetative patients may be more conscious of the world than we think. The Independent, October 16 2014

    Vegetative patients show glimmers of consciousness. BBC News, 17 October 2014

    Talking to vegetative state patients can help recovery. Daily Express, 16 October 2014

    Links To Science

    Chennu S, Finoia P, Kamau E, et al. Spectral Signatures of Reorganised Brain Networks in Disorders of Consciousness. PLOS Computational Biology. Published 16 October 2014



  • Exercise data signs could cut sugary drink intake

    “Signs warning shoppers how much exercise they need to do to burn off calories in sugary drinks can encourage healthier choices,” BBC News reports. Signs in shops in an area of Baltimore seemed to have led to a change in shopping habits amongst Afro-American teenagers.

    Researchers first studied beverage purchases by black teens at six corner stores in Baltimore.

    They then tested the effect on purchasing habits of displaying different types of calorie information, such as the number of calories in a sugary drink, or how much walking or running you’d need to do to burn off the calories.

    Overall, they found that displaying the information changed beverage purchases, with fewer sugary drinks purchased and fewer large drinks purchased, leading to fewer overall calories.

    Environmental interventions, including product information and advertising, are known to have some effect on purchasing intentions, so may be a way to target the obesity epidemic. However, it would be premature to generalise these results to other environments and populations at this stage.

    There has been a significant amount of research suggesting that that people habitually underestimate the amount of calories they eat, as well as the amount of exercise required to burn off these calories. Therefore, a case could be made that manufacturers could consider adding information such as exercise data to their products.

     

    Where did the story come from?

    The study was carried out by researchers from Johns Hopkins Bloomberg School of Public Health, Baltimore, in the US, and was funded by the Robert Wood Johnson Foundation through its Healthy Eating Research programme.

    The study was published in the peer-reviewed American Journal of Public Health.

    Both the BBC News and the Mail Online's reporting of the study was accurate.

     

    What kind of research was this?

    This was a type of case-crossover study, which aimed to look at the effect that displaying calorific information in different ways in a small sample of corner stores in the US had on the purchase of sugar sweetened beverages (SSBs) by US teenagers from black minority ethnic groups. 

    SSBs that were assessed by the study included “soda”, fruit drinks, sport drinks, vitamin water and “Hug” (a US product similar to Fruit Shoot).

    A traditional case-crossover study is one where each individual is being used as their own control. In one circumstance, they will be exposed to the risk exposure (the “case”), and in another they will be exposed to the “control” exposure. In this study, the exposure being altered is calorie information. Though described by the researchers as a case-crossover study, this wasn’t a traditional example of this study type, as they weren’t ensuring that it was the same individuals being exposed to each scenario. Rather, they were looking at the same environment (an area of inner-city Baltimore) after an exposure.

    It could also be considered to be a type of “before and after” study, where they are just looking at the differences before and after an intervention.

    The researchers say that consumption of SSBs is believed to be an important contributor to adolescent obesity, particularly among minority ethnic groups. The researchers report that SSB consumption makes up 15% of the daily calorie intake of minority adolescents, with black adolescents drinking at least twice the daily maximum of SSBs advised by American guidelines (eight to 12 ounces a day). Understanding the potential for environmental interventions is said to be essential for curbing the obesity epidemic.

     

    What did the research involve?

    This study was conducted in six corner stores in low-income black neighborhoods in Baltimore over a 10-month period, between 2012 and 2013. The target population was black adolescents aged between 12 and 18.

    They investigated the effect of displaying four different types of calorific information on SSBs:

    • absolute number of calories in the drink
    • number of teaspoons of sugar
    • minutes of running required to burn off the calories
    • miles of walking required to burn off the calories

    Each of these different pieces of information was displayed on a brightly coloured sign in a prominent location on the fridge containing drinks saying, respectively:

    • “Did you know that a bottle of soda or fruit juice has about 250 calories?”
    • “Did you know that a bottle of soda or fruit juice has about 16 teaspoons of sugar?”
    • “Did you know that working off a bottle of soda or fruit juice takes about 50 minutes of running?”
    • “Did you know that working off a bottle of soda or fruit juice takes about 5 miles of walking?”

    The signs were based on the estimate that the average 15-year-old would weigh around 50kg (110lbs).

    Information was collected of purchases by black adolescents who appeared to be aged 12 to 18 years. A random sample of 35 adolescent purchases per store per week was collected, with information recorded on whether or not the adolescent purchased a beverage and, if so, what type and size of drink.

    Over a four-week period, they collected baseline information of SSB purchases when no calorie information was available. Then the six stores displayed each of the different types of information for two weeks, during which time the information on adolescent purchases continued. There was a one week “washout” period between the different signs, where no sign was displayed. For a final six-week post-interventional period, all calorie information was removed.

    They also conducted a sample of interviews, where adolescents were stopped and asked whether they had noticed the signs, understood the information, and whether this had influenced their purchases.

    The main outcomes described in the study were:

    • whether an SSB was purchased
    • total number of calories
    • whether a large volume was purchased (above 16 ounces, as there had been recent local efforts to ban these sizes in food establishments)

     

    What were the basic results?

    Over the course of the study, information was collected on 4,516 purchases by black adolescents, 3,098 of which were for beverages of any type. This included 601 beverage purchases during the baseline weeks, 2,311 beverage purchases spread across all four calorie information interventions, and 186 beverage purchases in the post-intervention period.

    During the baseline week, just under three-quarters of purchases included a beverage, 97% of which were for SSBs, just over half of which were large volume SSBs, and mean calories of all beverages was 207kcal (206 for SSB beverages).

    During each of the interventions there was a change in beverage purchases, with fewer SSBs purchased, fewer large volume SSBs and fewer beverage calories. For example, across all four interventions, the calorie content of any beverage fell from 207 to 184kcal (206 to 196 for SSBs). The proportion of all beverage purchases that included an SSB fell to 89% and the proportion of SSB purchases that were large volume fell from 55% to 37%.

    Even in the post-intervention period, after removing the signs, SSB purchases, volume and total calories remained lower than at baseline.

    In the interviews, just over a third of adolescents reported seeing the calorie information displayed, 95% of whom reported understanding them, and 40% said they changed their purchase as a result.

     

    How did the researchers interpret the results?

    The researchers conclude that, “Providing caloric information was associated with purchasing a smaller SSB, switching to a beverage with no calories, or opting to not purchase a beverage; there was a persistent effect on reducing SSB purchases after signs were removed”.

     

    Conclusion

    This is an interesting study exploring how displaying different types of calorie information in corner stores may change SSB purchases among minority ethnic groups in the US.

    Environmental interventions, including product information and advertising, are known to have some effect on purchasing intentions, so may be a way to target the obesity epidemic.

    Many experts argue that we are now living in an "obesogenic environment", where the everyday world around us encourages unhealthy food. For example, a study we covered in March 2014 found an association between the number of fast food outlets in a given area and body mass index.

    However, little can be firmly concluded from this study. It has focused on studying only black adolescents in one specific region of the US, and has only looked at the effect of the interventions in six corner stores. We don’t know the effect of displaying such information in the wider population, or in different locations (for example fast food outlets, rather than just corner stores).

    It is also difficult in such a study to definitely know how much the intervention is having a direct impact on people’s purchasing habits. In this study, the sample of interviews helped to inform this, which suggested that around a third had noticed the signs, and it had influenced the subsequent purchases of 40% of people.

    The overall changes in beverage calories during and after the interventions was also fairly small (around 10-20kcal) so it is difficult to say whether or not this would have any meaningful effect on targeting overweight and obesity.

    Though environmental interventions are likely to be of some effect in targeting the obesity epidemic, the overall change needs to be towards a healthier, balanced diet in general, combined with regular exercise, rather than change in just one specific area, such as whether or not you purchase an SSB.

    Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

    Links To The Headlines

    Sugary drinks warning signs change habits of US teens. BBC News, October 17, 2014

    Run FOUR miles to burn off just one bottle of coke: Scientists call for exercise data to be printed on packaging instead of calories. Mail Online, October 17 2014

    Links To Science

    Bleich SN, Barry CL, Gary-Webb TL, Herring  BJ. Reducing Sugar-Sweetened Beverage Consumption by Providing Caloric Information: How Black Adolescents Alter Their Purchases and Whether the Effects Persist. American Journal of Public Health. Published online October 16 2014



  • Crash diets 'work best' claim misguided

    “Crash diets DO work, claim experts,” the Mail Online reports.

    It reports on an Australian study involving 200 obese adults who were randomly assigned to either a 12-week rapid weight loss programme on a very low-calorie diet or a 36-week gradual weight loss programme.

    It found that 81% of people in the rapid weight loss group achieved the target weight loss (more than 12.5% of their bodyweight), compared to 50% of those in the gradual weight loss group.

    Participants, from both groups, who lost more than 12.5% of their bodyweight were then placed on a weight maintenance diet for three years. However, 71% of the weight was regained in both groups after this three-year period.

    So it would appear, whatever the weight loss regime used, that the real challenge is keeping off the weight in the long term.

    The study may also not have captured the harmful effects that may be associated with rapid weight loss, such as loss of muscle mass or poor nutrition.

    If carefully supervised, very low-calorie meal replacements may be suitable for some people with obesity, at least as an initial measure, but they are not a long-term solution.

    The NHS Choices weight loss plan uses a combination of not just diet, but also exercise and lifestyle changes, to achieve sustainable and prolonged weight loss.

     

    Where did the story come from?

    The study was carried out by researchers from the University of Melbourne and La Trobe University, Australia. It was funded by the Australian National Health and Medical Research Council and the Sir Edward Dunlop Medical Research Foundation.

    One of the authors of the study has a history of previous employment with Nestle’s Optifast. Optifast was used as the low-calorie food substitute for the rapid weight loss group. Though Nestle played no role in either the funding, design or analysis of the study.

    The study was published in the peer-reviewed medical journal The Lancet Diabetes and Endocrinology.

    The study was covered widely and not always accurately in the media. The message in The Daily Telegraph that “crash diets” are more effective than gradual weight loss is misleading. Though more people achieved the target weight loss in the rapid weight loss group initially, in the long-term maintenance phase of the trial, 71% of both groups regained the weight they had lost.

    Encouraging all people to go on crash diets is inadvisable – it should be pointed out that in this study, participants were carefully supervised by professionals experienced in treating obesity.

    Reassuringly, most sources included information regarding the potential risks of low-calorie diets such as kidney damage and lack of adequate nutrition.

     

    What kind of research was this?

    This was a randomised controlled trial (RCT), which aimed to compare the effect of rapid and gradual weight loss programmes on both the rate of weight loss and the rate of weight regain in obese people.

    The authors say that guidelines recommend gradual weight loss for the treatment of obesity on the grounds that weight lost rapidly is more quickly regained. However, there is evidence to suggest that this is not necessarily the case.

    This RCT took place in two phases: an initial phase where people followed a rapid weight loss or gradual weight loss programme, followed by a second phase where those who had achieved the target weight loss entered the same longer-term maintenance phase.

     

    What did the research involve?

    The two phase trial took place between 2008 and 2013. It included 200 obese adults who were otherwise healthy and aged between 18 and 70 years. In the first phase, 103 participants were randomly assigned to a 12-week rapid weight loss (RWL) programme on a very low-calorie diet (450-800 kcal per day), and 97 were assigned to a 36-week gradual weight loss (GWL) programme, which reduced energy intake by 400 to 500 kcal a day, in line with current dietary guidelines in Australia, where the study took place.

    Those in the RWL group consumed a commercially available "very low energy" meal (Optifast) instead of the usual three meals a day, following the manufacturer’s recommendations. The aim for this group was 15% weight loss during the 12 weeks (about 1.5kg per week). In the GWL programme, participants used one to two of the commercial meal replacements with the aim of 15% weight loss over 36 weeks (about 0.5kg per week).

    All participants received the meal replacements free, and were given similar material on dietary education.

    Those who achieved 12.5% weight loss or more in the allocated timeframe were eligible to enter the second phase of the trial, which continued for 144 weeks. In this phase, participants were instructed to follow an individualised diet for weight loss maintenance, based on Australian guidelines. They had individual sessions with dieticians at weeks four and 12 and then every 12 weeks. Adherence to the diet was assessed and those regaining lost weight were advised to follow an energy reduced diet (400-500 kcal a day less).

    Throughout the study all participants were instructed to take 30 minutes or more daily of mild to moderate intensity exercise. Physical activity was measured using a pedometer worn for seven consecutive days.

    Total study duration was three years for the RWL group and 3.5 years for the GWL group.

    The main outcome examined was the average weight loss maintained at week 144 of the trial, in the second phase. Participants were weighed after fasting overnight. Their waist and hips were measured and their body composition analysed. Other outcomes examined were blood levels of certain hormones associated with appetite (ghrelin and leptin), and participants’ subjective appetite.

    In their analyses, they looked at only those who had completed the trial, and carried out intention to treat analysis (ITT), in which all participants are included in the results, whether or not they have dropped out.

     

    What were the basic results?

    In the first phase of the trial, more participants in the rapid weight loss group achieved the target weight loss and started phase two of the trial (76 people; 81%) compared to participants in the gradual weight loss group (51; 50%)

    However, at the end of the weight maintenance phase, there was no difference between groups in the proportion who regained weight. Looking at only those who completed the study (43/51 in GWL and 61/76 in RWL), roughly equivalent proportions in each group had regained most of their lost weight: 71.2% of the gradual weight loss group (95% confidence interval [CI] 58.1 to 84.3), and 70.5% of the rapid weight loss (95% CI 57.8 to 83.2).

    Intention-to-treat analysis showed similar results: gradual weight loss 76.3% regain (95% CI 65.2 to 87.4) vs rapid weight loss 76.3% regain (95% CI 65.8 to 86.8).

    Looking at adverse effects, during the first phase of the trial one person in the rapid weight loss group developed acute cholecystitis (gallbladder inflammation) and had to have their gallbladder removed. This adverse effect was considered to be “probably related to the rapid weight loss programme”.

    During the second phase of the trial, two people in the rapid weight loss group developed cancer (multiple myeloma and breast cancer), but these adverse effects were not considered to be related to the dietary intervention.

     

    How did the researchers interpret the results?

    The researchers say their findings show that the rate at which weight is lost does not affect the rate at which it is regained during the weight loss maintenance period. These findings, they say, are not consistent with current dietary guidelines, which recommend gradual rather than rapid weight loss. They also point out that RWL was more likely to lead to target weight loss and fewer drop outs.

    They say it is possible that low-energy meals are easier to follow because fewer choices have to be made than for a diet consisting of regular foods. The limited carbohydrate intake of very low-calorie diets may induce ketosis (where the body uses fat for energy), which might promote feelings of fullness. Losing weight quickly may also motivate people to persist with their diet and achieve better results, they argue.

    The authors say that long-term weight regain is probably caused by a rise in levels of the hormone ghrelin after a weight loss programme. Experts should now focus on the safety of appetite suppressants to help prevent weight regain, they say.

     

    Conclusion

    This study challenges the widely held view that losing weight gradually, as recommended in current guidelines, results in better long-term weight reduction and less weight regain compared to losing weight rapidly using a very low-calorie diet.

    The study found that though initially more people in the rapid weight loss group achieved the target weight loss compared to the gradual weight loss group, when these participants then entered the longer-term maintenance phase where all followed individualised diets. Equivalent proportions in each group then regained weight.

    The sad fact seems to be that whatever type of diet is followed, maintaining weight loss in the long term is the real challenge.

    The study had some limitations. As the authors point out, the main weakness was its exclusion of people who smoked, had diabetes, took weight-altering drugs or were severely obese. Many people with obesity also have diabetes and are often smokers. This makes it difficult to know if the results are generalisable to the average person seeking medical assistance with weight loss.

    It is also important to recognise that this study may not have captured the harmful effects that may be associated with rapid weight loss. This study did observe that one person in the rapid weight loss group developed acute gallbladder inflammation, and this was attributed to the weight loss programme being followed. Rapid weight loss can also result in greater loss of muscle mass, and a very low-calorie diet may be short of essential nutrients.

    It is possible that for some obese adults, a carefully supervised very low-calorie diet may be a suitable option, at least as an initial measure, but they are not a long-term solution and do not solve the goal of long-term maintenance of a healthy weight.

    The best way to achieve a healthy weight and maintain it in the long term is likely to involve a long-term commitment to a lifestyle change, involving a healthy, balanced diet with regular exercise in line with government recommendations.

    Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

    Links To The Headlines

    Crash diets DO work, claim experts - but can still be dangerous as it is 'impossible' to gain all the nutrients the body needs. Mail Online, October 16 2014

    Crash-dieting more effective than gradual weight loss, study suggests. The Daily Telegraph, October 16 2014

    Crash diets might not be so bad in beating fat after all, suggests new study. The Independent, October 16 2014

    Crash dieting IS the best way to loose weight, say experts. Daily Express, October 16 2014

    Links To Science

    Purcell K, Sumithran P, Prendergast LA, et al. The effect of rate of weight loss on long-term weight management: a randomised controlled trial. The Lancet Diabetes & Endocrinology. Published online October 16 2014