Beyond body mass index: rethinking doctors’ advice for weight loss

Limited evidence for lifestyle interventions

Lifestyle interventions have for many decades been the mainstay recommendation to reduce weight in people with obesity. However, such an approach has important limitations. A systematic review published in 2022 encompassing 13 trials found that adults with a BMI ≥25 randomised to lifestyle and weight loss interventions lost 1.8 kg on average after two years (95% confidence interval 2.8 to −0.8 kg), compared with usual care.2 This indicates that lifestyle interventions are largely ineffective in providing sustained long term weight loss. For children and adolescents, low to very low certainty evidence indicates similar findings.101112

The same seems true for the mortality benefits of lifestyle interventions for weight loss: in 2013, the Look Ahead randomised controlled trial, which included 16 study centres and 5145 participants with obesity and type 2 diabetes, found that although intensive lifestyle intervention for weight loss improved some cardiovascular risk factors, it did not affect the risk of either microvascular or macrovascular complications or cardiovascular death.13

The Look Ahead study was included in a systematic review of randomised controlled trials that found that lifestyle intervention for weight loss in people with prediabetes or type 2 diabetes did not reduce cardiovascular or all-cause mortality.3 The meta-analyses on cardiovascular mortality, which included 11 017 participants with a mean age of 54.6 and a mean BMI of 31.8, found a relative risk of cardiovascular death of 0.99 (95% CI 0.79 to 1.23) compared with usual care. For all-cause mortality, the relative risk was 0.93 (0.85 to 1.03) compared with usual care, based on 16 554 participants with a mean age of 55.5 years and a mean BMI of 30.5.3 However, the reduction in risk may be attributable to confounders such as changes in exercise or eating habits or other changes in life conditions related to the interventions rather than weight loss itself.14

Another systematic review and meta-analysis of lifestyle interventions for weight loss in mixed BMI populations indicated an absolute risk reduction of 15 This, of course, might not apply to the extreme accumulation of adiposity.16

These studies suggest that although lifestyle interventions for weight loss might help patients improve cardiovascular risk factors such as blood pressure, they do not result in a reduced incidence of cardiovascular events or mortality. Even though a healthy lifestyle provides important benefits, weight does not seem to be the determining factor in achieving these benefits. For instance, a study including 11 761 participants found a linear association between the number of healthy habits and mortality independent of weight.17 This suggests that people with a high BMI can be healthy and that high weight may not be such an important indicator of health as we have traditionally considered it. Furthermore, structural public health interventions that include reducing barriers to physical activity and facilitating access to healthy nutrition may be more effective than individually targeted lifestyle interventions for weight loss to improve health.18

Harms of focusing on weight

Focusing on weight loss might contribute to societal weight bias—that is, negative attitudes, assumptions, and judgments about people based on their weight.1920 Weight bias has been identified in children as young as 3 years old, who associate children with larger bodies with negative characteristics21 and prefer not to play with or help them.2223 Weight bias may not only have adverse effects on mental health but may also be associated with disordered eating, the adoption of unhealthy habits, and weight gain.24

Being labelled as overweight or obese is interconnected with weight bias, as it increases the risk of developing disordered eating, internalised weight stigma, and body dissatisfaction.2526 Eating disorders and weight dissatisfaction, in themselves, are associated with an increased risk of type 2 diabetes and thus might cause physical harm.272829 The Eating Disorders in Weight Related Therapy (EDIT) Collaboration conducted a systematic review of evidence from randomised trials and was unable to identify a higher risk of eating disorders in weight loss interventions. However, only a few studies provided evidence for this outcome, and they all had short term follow-ups.30 Most of the included trials compared two or more weight management intervention groups, hampering the ability to identify any differences. The collaboration has published a protocol for a meta-analysis of individual patient data to clarify this issue.31

Lifestyle interventions rely on the individual’s ability to, for example, restrict energy intake and perform physical activity. People with high weight or large bodies are often negatively stereotyped as lazy or lacking discipline, resulting in them self-blaming when unable to lose weight.3233 As lifestyle interventions fail to result in substantial weight loss in most people who try, the efforts may contribute to internalised stigma, where an individual unconsciously adopts the externally ascribed characteristics.3435 Internalised stigma is associated with disturbed eating, self-harm, depression, and suicidal ideation.36 Furthermore, experience of weight discrimination is associated with increased mortality,37 and some of the excess morbidity and mortality found in people with high BMI may be explained by the downstream consequences of discrimination and stigma.38

The harms related to weight bias are not just interconnected but also linked to other social inequalities based on factors such as gender, sexuality, class, and ethnicity.4567 These factors combine to form unique forms of discrimination, stigmatisation, and stereotypes.43940 Furthermore, these intersections are also associated with an increased risk of obesity in these groups, which highlights the complex burden of high weight and stigma in these subpopulations.41

What do clinical practice guidelines say?

Weight bias and weight stigma are increasingly referenced in international guidelines for managing obesity. For example, Obesity Canada, a non-profit organisation aimed at improving the lives of people with obesity, has published a comprehensive framework to reduce weight bias and stigma, Reducing Weight Bias in Obesity Management, Practice, and Policy.8 The clinical guidance includes avoiding stigmatising language and images, emphasising the limited benefit of individual lifestyle interventions, and focusing on health and quality of life for patients irrespective of their size.8 The American Association of Clinical Endocrinology suggests focusing on surrogates other than weight to reduce internalised weight bias.42 The update of the Argentinean guideline on the integral management of obesity in adults includes guidance on obtaining consent for weighing patients and being careful about ascribing patients’ symptoms to their weight, among other initiatives to reduce weight stigma in consultations.43

The Canadian and Argentinean guidelines both emphasise the importance of creating inclusive environments in clinical practice for people of different body sizes, including chairs, beds, and blood pressure cuffs.44 The Canadian guideline for managing obesity in adults has proposed five As,45 where the first A stands for asking permission to discuss weight, allowing a non-judgmental exploration of patients’ preferences and motivations. For patients whose weight has remained unexplored in previous consultations, this could offer the opportunity to discuss weight and provide them with the information about health and weight that is necessary to make informed healthcare choices.

Researchers have proposed that, for interventions with limited benefits and important harms, patients should be given the option to do nothing.46 Obesity Canada recently published guidelines for children,47 and its guidelines for adults have been adapted for use in Chile and Ireland.48 However, this may have a limited impact without a thorough reform of the competencies of healthcare professionals, who are currently trained in weight centric approaches.49

Although awareness of weight stigma is growing, lifestyle interventions focusing on weight loss are often recommended in guidelines as primary treatments without acknowledging potential harms or their relation to weight bias (table 1). This does not mean that doctors necessarily contribute to stigma by following such guidelines, but the guidelines miss the opportunity to support clinicians in reducing weight bias in the management of obesity. Without these considerations and adequate support for patients and clinicians, recommendations to improve lifestyle that are designed to avoid weight bias can become generic and stigmatising weight loss advice.57

Patient centred care

Alternative weight inclusive approaches, such as Health at Every Size (HAES), centre on health and acknowledge the social determinants of health and that good health can be achieved regardless of weight loss.58 HAES aligned approaches, including intuitive eating and enjoyable physical activity, have shown promising results in improving eating behaviours in selected populations (primarily women).59 As with other approaches, these should be evaluated in large randomised controlled trials, including systematic assessment of harms and benefits.

Although evidence is lacking in this emerging field, doctors can learn from such approaches and current trends in guidelines to provide better and more compassionate care for patients with larger bodies (box 1). This includes ensuring that equipment and clinic facilities accommodate larger bodies. It also involves seeking permission to discuss weight and being mindful of the term the patient prefers to use to describe their body.

Systematically recommending weight loss, without being mindful about the potential harm, might also medicalise high weight and implicitly endorse a normative perspective on weight, whereby higher weight is inherently considered undesirable and unhealthy, thus promoting the necessity of weight loss.60 This embedded normativity underlies weight bias in society, putting pressure on both doctors and patients to pursue the often frustrating and challenging goal of losing weight. If doctors are aware of these pressures and concentrate on asking, listening, and deciding together what is most important, they can mitigate some of the unintended harms of current approaches. Patients may still wish for weight loss advice, and doctors should be prepared to engage in conversations with their patients about the drivers for weight loss, potentially identifying internalised weight stigma, cultural experiences, and social pressures surrounding the desire to lose weight, as well as social determinants of health.

Thus, doctors should be prepared to inform individuals seeking weight loss about the potential benefits and harms of interventions and minimise the risk of developing eating disorders and long term impacts on metabolism. Pharmacological interventions, including GLP-1 receptor agonists, might reduce weight and other hard outcomes, but they are associated with frequent gastrointestinal side effects, and weight regain is expected when patients discontinue treatment.61 These weight centric pharmacological approaches raise similar concerns to lifestyle interventions in terms of potential stigma. Furthermore, the present indications for pharmacological weight loss may include 20-30% of the population in most countries, and their implementation requires important public health considerations.62 If the final decision is to pursue changes in lifestyle for weight loss, use of weight loss drugs, or bariatric surgery, the goals should be defined by outcomes important to the individual instead of pre-specified anthropometrics.

Focusing on weight, doctors would need to spend a large proportion of their time providing ineffective advice on lifestyle changes, which would affect their ability to provide person centred care for other conditions in which they can be more helpful.5545Structural public health interventions, including reducing barriers to physical activity and facilitating access to healthy nutrition, may be more effective than individually targeted lifestyle programmes in improving health in people with high weight.18

Such a patient centred approach is likely to provide better care by aligning with patient preferences and circumstances while also reducing weight bias. Moreover, clinicians can be trained to routinely integrate the concepts of weight bias and weight stigma with other clinical parameters for managing obesity and to raise awareness of the prevalence of eating disorders and disordered eating.49 While the societal nature of weight bias limits the extent of change possible within individual consultations, clinicians can have a critical role by ensuring their practices do not reinforce such biases. Doctors’ advice about healthy eating and physical activity is still relevant as it may result in better health. The main goal is to offer good care irrespective of weight, which means not caring less but rather discussing benefits, harms, and what is important to the patient.