This research is from the Prevention Group which spans the MRC Epidemiology Unit and Primary Care Unit within Cambridge Population Health Sciences.

Yesterday Professor Simon Griffin accepted the Paper of the Year award at the Royal College of General Practitioners annual conference on behalf of lead author Dr Amy Ahern and coauthors of the Lancet paper ‘Effectiveness and cost-effectiveness of referral to a commercial open group behavioural weight management programme in adults with overweight and obesity: 5-year follow-up of the WRAP randomised controlled trial’.

The WRAP trial studied the long-term impact of two durations of a commercial weight-loss programme (WeightWatchers) on weight, type 2 diabetes and obesity-related diseases in 1,267 people with overweight or obesity, compared to standard care. Watch a short video introducing the WRAP trial:

In a second video WRAP Trial chief investigator Dr Amy Ahern discusses their findings, which indicate that the assumption that all weight lost with commercial weight management programmes is regained within five years is incorrect, and the implications this has for healthcare costs.

Read more

• Ahern Al et al. Effectiveness and cost-effectiveness of referral to a commercial open group behavioural weight management programme in adults with overweight and obesity: 5-year follow-up of the WRAP randomised controlled trial. Lancet (2022) DOI:10.1016/S2468-2667(22)00226-2

In this article originally published in The Conversation, Dr Amy Ahern and Professor Giles Yeo discuss why is it so difficult to keep the weight off after you’ve lost it. This research is from the Prevention Group which spans the MRC Epidemiology Unit and Primary Care Unit within Cambridge Population Health Sciences.

It is often said that 95% of weight-loss measures don’t work. Only, it’s not true. Advances in behavioural treatments (such as cognitive behavioural therapy) for obesity and weight-loss drugs mean there are lots of approaches that help people lose weight.

In fact, weight loss is the easy part (relatively speaking). The problem is that when you come off a diet or stop taking a weight-loss drug, the weight will invariably creep back up.

To be clear, this does not mean that diets and other obesity treatments are useless. Far from it. In a recent study, published in Lancet Public Health, researchers checked in on participants five years after they took part in a 12- or 52-week WW programme (formerly called Weight Watchers). Although, on average, people’s weight had crept back up, some weight loss – about 2kg, on average – was sustained for up to five years.

Even this short time at a lower weight can substantially reduce a person’s lifetime risk of developing diabetes, heart disease and other weight-related diseases. But for people with obesity, and their healthcare providers, weight regain can be demoralising.

The stigma surrounding obesity, which views a person’s weight as their responsibility, means that this “failure” of treatment is often felt as a personal failing. This is not true. So why does the weight come back on?

Your brain doesn’t want you to lose weight

There are a few reasons why the weight creeps back on. First, our brain hates it when we lose weight. It considers this a reduction in our chances of survival, so it does everything in its power to drag your weight back up.

As you lose weight, your brain reduces your metabolic rate (the rate at which your body burns calories), making you subtly more efficient. The reality is, if there are two people of identical weight, one weight stable and the other having just lost weight, the latter will have to eat less food to remain the same weight.

It turns out that a hormone secreted from fat called leptin is largely responsible for this. One of leptin’s key roles is to let the brain know how much fat you are carrying. The more fat you have, the more leptin is produced. So when you lose weight, your brain senses the corresponding drop in leptin.

What is exciting is that scientists have shown that if you administer just enough leptin to fool your brain into thinking you haven’t lost any weight, then many of these weight-loss-related changes are mitigated. There is no treatment based on these findings yet –– but watch this space.

As well as these biological causes, each person with obesity has their own combination of psychological, social, environmental and economic factors that have contributed to them gaining weight. Most of these will not resolve during a weight-loss treatment.

People with obesity who have lost weight still live in an environment where energy-dense, nutritionally poor food is widely available, heavily promoted, cheaper and more convenient. Social activities often centre around food. We celebrate with food, commiserate with food, and use food as both comfort and reward. Eating less requires continuous thought and considerable effort.

Behavioural treatments for obesity, such as commercial group programmes or cognitive behavioural therapy, teach us strategies that can help us to manage this, but they don’t stop it from being difficult. They also can’t make our lives easier.

Daily stressors and life events can disrupt the healthy habits and routines that people establish when trying to lose weight, while drugs that work to target biological drivers only work while they are being taken. Surgery also works to address biological drivers, but biology fights back.

Chronic treatments

It is unrealistic to expect that a one-off intervention will lead to permanent weight loss. If we take the example of high blood pressure medication, which is very effective, no one is countenancing stopping the treatment once your blood pressure has normalised. It would simply come back up again. The same is true for weight-loss treatment.

Obesity is perhaps best thought of as a chronic relapsing condition. People with obesity need lifelong access to treatment and support. Rather than dismissing effective treatment options because of weight regain, we should be honest with people about what treatments can achieve and the likelihood of needing ongoing support. After all, chronic conditions require chronic treatments.

The prevailing view of society is that obesity is a simple problem: simply eat less and move more. Thus, people with obesity just need to be “fat shamed” into becoming thin. However, people with obesity are not bad, lazy or morally bereft; they are fighting both their biology and their environment. Obesity is not a choice.

Amy Ahern, Principal Research Associate, MRC Epidemiology Unit, University of Cambridge and Giles Yeo, Professor of Molecular Neuroendocrinology, MRC Metabolic Diseases Unit, University of Cambridge, University of Cambridge

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Image credit: World Obesity

This research is from the Prevention Group which spans the MRC Epidemiology Unit and Primary Care Unit within Cambridge Population Health Sciences.

They say a picture can convey a thousand words, and researchers have found that using medical imaging technologies that can visualize health may discourage risk-related behaviours more than non-visual information. The meta-analysis, published by scientists at the University of Cambridge’s Department of Public Health and Primary Care and MRC Epidemiology Unit in the open access journal PLOS Medicine, finds that when individuals undergo an imaging procedure and are shown visual personalized information about their own risk of disease, they may be more likely to reduce risky behaviours.

Non-communicable diseases are estimated to account for over two-thirds of deaths worldwide each year and are linked to behaviours such as smoking, poor diet, and lack of physical exercise. Behaviour change can reduce risks and many interventions intend to motivate such change. Researchers are keen to understand whether the growing use of medical imaging technologies could help.

Professor Simon Griffin from the MRC Epidemiology Unit, a senior author on the paper, commented:

Most studies suggest that provision of information about disease risk in verbal or written format does not lead to sustained changes in health-related behaviours. However, this review suggests that sharing the results of medical imaging appears to be a more effective motivator of behaviour change.”

The researchers  conducted a meta-analysis of 21 randomized controlled trials involving over 9,000 adult participants. Participants were either shown visual examples of personalized risk information following an imaging procedure, such as computed tomography, ultrasound, or radiography, in addition to health information or advice, or they received health information or advice with no visual feedback. The trials reported on behaviours including smoking, medication use, physical activity, diet, oral hygiene, sun protection, tanning booth use, blood glucose testing, skin self-examination, and foot care.

The strongest evidence was for smoking reduction, a healthier diet, increased physical activity, and increased oral hygiene behaviours. Single studies also reported increased skin self-examination and foot care following visualized feedback. The other behaviours were improved by visual interventions, but results were not statistically significant. The authors conclude that the growth of medical imaging technology could be capitalized on to help people change and reduce disease risks.

Dr Gareth Hollands, a researcher at the Department of Public Health and Primary Care and first author on the paper, commented:

Medical imaging scans are used ever more widely by healthcare professionals. By gathering together the existing research, this study suggests that showing the scan results to patients to highlight the state of their health could motivate them to behave in a healthier way.”

• Read the paper: Gareth Hollands, Juliet A Usher-Smith, Rana Hasan, Florence Alexander, Natasha Clarke, Simon J Griffin. Visualising health risks with medical imaging for changing recipients’ health behaviours and risk factors: Systematic review with meta-analysis. PLOS Medicine 03 March 2022.

By Dr Jean Strelitz, MRC Postdoctoral Fellow, MRC Epidemiology Unit. This research is from the Prevention Group which spans the MRC Epidemiology Unit and Primary Care Unit within Cambridge Population Health Sciences.

People with type 2 diabetes have a higher risk of heart disease and premature death. People with type 2 diabetes are increasingly encouraged to lose weight, as evidence from numerous clinical trials shows that weight loss substantially improves blood sugar levels. Indeed, a recent trial of intensive weight management in people with type 2 diabetes in the UK achieved remission in about half of the participants with type 2 diabetes, so that they no longer needed to take drugs to manage their blood sugar.  What remains unanswered, is whether weight loss can also help lower patients’ risk of heart disease.

Unanswered questions on weight loss and heart disease.

While weight loss can improve blood sugar levels, questions remain regarding the impact on downstream consequences of diabetes such as heart disease and premature mortality.

To address this we undertook a systematic review of the published literature of observational  studies and intervention trials reporting weight loss and other weight changes and heart disease among people with type 2 diabetes. To be included in our analysis weight data had to be collected at least two occasions over the course of the study to measure weight changes, and we identified 17 studies on this topic that met our criteria, 14 of which were observational studies and 3 behavioural intervention trials. We didn’t include studies of bariatric surgery because this has other health impacts on heart disease risk unrelated to weight loss. We instead focused on studies of behaviour-based weight loss.

Results from our review showed that weight gain among people with type 2 diabetes was associated with increased risks of heart disease and death, but the results for weight loss were more mixed. Several studies distinguished between intentional weight loss and unintentional weight loss, finding that unintentional weight loss was associated with a higher risk of death from all causes, consistent with this weight loss being a symptom of an underlying illness.

Intentional weight loss and unknown consequences

Our review found that there have been few studies that assessed whether intentional weight loss protects against heart disease and death. Indeed the three behavioural interventions targeting weight loss showed no impact on the risk of cardiovascular disease events such as heart attack or stroke during 5-10 year follow up periods.

Studies showed conflicting results and were influenced by bias, highlighting the need for high-quality research to inform weight loss guidance for patients.  Differences between the studies regarding the duration of weight loss, whether the study accounted for unintentional weight loss, the duration of follow-up for heart disease risk, and other individual characteristics contribute to differences in the findings. There was evidence of moderate bias in most of the studies we included, due to factors such as the method of weight assessment used, and whether the study controlled for common confounding factors like smoking.

Our review suggests that preventing weight gain in people with type 2 diabetes may reduce risk of heart disease and mortality. However, while there is growing evidence for the short-term benefits of behavioural weight loss interventions on risk factors such as blood sugar levels, there is a lack of evidence to support such interventions for preventing heart disease and death in adults with type 2 diabetes. Another recent paper from our group found in a study of more than 2,000 people with type 2 diabetes that a large amount of weight loss (more than 10% of body weight) during the five-year period after diabetes diagnosis was associated with a two-fold increased risk of premature death from any cause. The risk of death after weight loss was highest among participants who did not have obesity at the time they were diagnosed, suggesting obesity could be a particular factor in how patients are affected by losing weight.

Time for a more tailored approach to weight loss

Taken together with the results of our systematic review this suggests that we need more evidence to inform weight loss advice and support for people with  type 2 diabetes, as some may be affected differently from others. Considering that weight loss may affect patients differently, a more tailored approach that reflects how individuals with type 2 diabetes may respond differently to weight loss may be more effective.

In order to determine which patient groups will benefit from behavioural weight-loss interventions, and what amount of weight loss is most effective in preventing heart disease, long-term follow up of behavioural intervention studies is needed. Accumulating this evidence will take time, but it will inform policy concerning weight management advice, help us to allocate health service resources more effectively, and enable us to better support people with diabetes.

 Find out more

• Jean Strelitz, Emma R. Lawlor, Yue Wu, Annabel Estlin, Giri Nandakumar, Amy L. Ahern, Simon J. Griffin “Association between weight change and incidence of cardiovascular disease events and mortality among adults with type 2 diabetes: a systematic review of observational studies and behavioural intervention trials” Diabetologia, 02 Dec 2021 https://doi.org/10.1007/s00125-021-05605-1
• Type 2 diabetes weight loss recommendations could be harmful for some, depending on BMI – Jean Strelitz, MRC Epidemiology Unit Research Blog, 16 December 2020
• Type 2 diabetes: losing even a small amount of weight may lower heart disease risk – Jean Strelitz, MRC Epidemiology Unit research blog, 13 May 2019.

Cambridge scientists involved in detailed analysis highlighting the need for multi-disciplinary capability for research into whole-system influences on behaviour and public health.

Non-communicable diseases like cancer, diabetes and heart disease have a huge impact on our quality of life and put pressure on the NHS and other services, especially as our society lives longer. To prevent these diseases, we need to better understand how the social and physical environments interact to play a role in their development. [Read more…]

A third of women who get diabetes while pregnant – a common condition called gestational diabetes mellitus or GDM – will go on to develop type 2 diabetes within 15 years of their pregnancy.

The figures show that the risk of developing type 2 diabetes after a pregnancy with GDM is much more variable than previously thought and persists into later life.

This research is from the Prevention Group which spans the MRC Epidemiology Unit and Primary Care Unit within Cambridge Population Health Sciences. [Read more…]

In this article for The Conversation, Dr Jean Strelitz discuss research showing how advising weight loss to all people with type 2 diabetes may not be the best approach. This research is from the Prevention Group which spans the MRC Epidemiology Unit and Primary Care Unit within Cambridge Population Health Sciences.

People with type 2 diabetes are often encouraged to lose weight, as this can help return their blood sugar to normal levels. But few studies have actually looked at how weight loss affects these patients’ long-term health, including their risk of heart disease (the most common diabetes complication and the leading cause of death) and risk of premature death. This is what our latest study sought to investigate.

Our results showed that large weight loss (more than 10% of body weight) during the five-year period after type 2 diabetes diagnosis was associated with a two-fold increased risk of premature death from any cause. The risk of death after weight loss was highest among participants who did not have obesity at the time they were diagnosed, suggesting obesity could be a particular factor in how patients are affected by losing weight.

Our study included 2,730 adults with a new diagnosis of type 2 diabetes from the UK, Denmark, and the Netherlands. Their ages ranged from 40 to 69, and 42% were women. Our aim was to understand whether weight loss after a diabetes diagnosis was associated with risk of heart disease and mortality, and whether short- and long-term weight loss had different effects.

We first measured participants’ weight at the time of their diabetes diagnosis, then again one year and five years later. Then, for the next five years, we tracked information on participants’ heart disease diagnoses and deaths from hospital records and national registries.

Patients who gained weight in the year after diagnosis were three times more likely to die by the end of the 10 year study than those who maintained their weight. Losing weight and then regaining was also associated with double the risk of death.

Over the five-year period, steady, moderate weight loss showed no effect on heart disease or mortality. And large weight loss led to no increased risk of death among people who had obesity. But those who did not have obesity and lost more than 10% of their body weight had more than three times the risk of death than someone who maintained their weight.

We didn’t find any associations between weight changes and risk of heart disease across any of the time periods we studied.

Our study is one of the first to show that weight loss may have different effects on different diabetes patients, depending on their body mass index (BMI).

Other studies have shown that large amounts of weight loss among people with diabetes may increase risk of death. However, these findings were often attributed to unintentional weight loss, or weight loss due to being unwell.

The participants in our study were given an information booklet on healthy diet and exercise habits, but they were not given any specialised support to lose weight. While people with a recent diagnosis of type 2 diabetes are often motivated to make healthy lifestyle changes, it’s possible that the weight loss seen in our study’s participants was unintentional.

However, we used information on age and participants’ self-rated health to see whether these factors might have affected the results from our study. We did not see any evidence of bias from unintentional weight loss due to older age or poor health, so we don’t think that unintentional weight loss entirely explains our results.

Why is weight loss a risk?

It’s unknown why weight loss would increase risk of death. It’s possible that other factors besides BMI are important, such as diabetes severity or having other chronic health conditions like cancer, as these all affect a person’s risk of death. We also checked if age was important in how weight loss affected mortality, though there weren’t any differences in the effect of weight loss on mortality for younger or older people.

Someone’s behaviour related to diet and exercise, and whether they have other illnesses, may also affect their mortality risk. A balanced diet and regular exercise lowers a person’s cardiovascular risk factors like blood pressure and cholesterol. But this study was not able to explore these other factors. In order to figure out which patients might benefit from weight loss, and which might be harmed, more research should consider these other factors besides BMI.

Although patients with type 2 diabetes receive personalised medical treatment depending on factors such as their blood sugar levels, whether they have other health conditions, and what medications they take, weight loss advice unfortunately doesn’t follow a similar approach. Instead, patients who are overweight are typically advised to reduce their calorie intake, or exercise more, following international guidelines.

Based on our study’s results, it’s possible that advising weight loss to all people with type 2 diabetes may not be the best approach. Instead, weight loss advice for people with type 2 diabetes should also be tailored, to reflect that weight loss may affect patients differently.

Jean Strelitz, Postdoctoral Research Fellow, Epidemiology, University of Cambridge

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Cambridge University MPhil courses in epidemiology, public health and primary care are evolving in to a new MPhil in Population Health Sciences (PHS). This new course is jointly run by the MRC Epidemiology Unit, Department of Public Health and Primary Care, and the MRC Biostatistics Unit (BSU), with contributions from colleagues across the University.

The MPhil in Population Health Sciences is a postgraduate master’s course, with specialisation streams covering the academic disciplines of health data science, infectious diseases, epidemiology, global health, public health, and primary care research. MRC Epidemiology Unit staff will teach courses across all these streams, including a brand new module in global health. [Read more…]