NO WEIGH! for professionals

Healthcare professionals should be practicing non-judgemental, evidence-based care. The onus is on us to educate ourselves and ensure that we are working in every patient's best interest, doing no harm, respecting autonomy, and practicing fairly and without discrimination. 

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Weighing Scales and BMI

The Quetelet Index was named after Adolphe Quetelet, a Belgian social scientist in the mid 1800s. He was fixated on the “average man” (l’homme moyen), whom he believed was the ideal for all of society. He theorised that it was possible to determine several things about a person by measuring the ratio between their weight and height. None of these things had to do with health or disease prevention.

The Quetelet Index was based on White European Men and did not take Women, Black, Indigenous, or People of Culture into consideration. In addition, he had some problematic beliefs around criminology and associated with a number of race scientists and eugenicists.

In 1975, a physician named Dr Ancel Keys published an article in the Journal Of Chronic Diseases entitled “Incidences of relative weight and ob*sity”. He renamed the Quetelet index the Body Mass Index, and BMI was born. Dr Keys was part of the Minesotta Starvation Experiment and in 1975, he published a book entitled “How to Eat Well and Stay Well the Mediterranean Way” with his wife Margaret.

At the time of publication, Keys stated that BMI was “if not fully satisfactory, at least as good as any other relative weight index as an indicator of relative obesity”. He also made it clear that it was only appropriate for population studies, and inappropriate for individual evaluation.

By the Mid 1980s, the BMI had taken over from the  height and weight tables, that were created by US life insurance companies as a way of charging people in larger bodies higher premiums.

By 1985, the National Institute of Health had revised its definition of ob*sity to include BMI, and in 1998 they changed the goalposts and lowered the threshold so that millions of people became ov*rweight/ob*se overnight. They did this without any real evidence that it would benefit anyone, and in spite of numerous concerns raised by experts at the time.

BMI is only really applicable to White European men, since it’s validity has never been tested on Women, Black or Indigenous people, and People of Culture. 

BMI is not a good predictor of metabolic health.  One study found that 50% of people with a BMI >25 were cardio-metabolically healthy. It looked at over 44, 000 participants from the 2005–2012 National Health and Nutrition Examination Survey (NHANES study), and used blood pressure, triglyceride, cholesterol, glucose, insulin resistance and C-reactive protein data as outcome measures.

In addition, 1/3 of the study population classified as “ob*se” were deemed healthy and 1/3 of people with a “normal BMI” were found to be unhealthy. In other words, BMI has a 50% false positive rate and a 30% false negative rate, so it is only accurate 1 in 3 times. Yet medical professionals use BMI as a predictor of cardio-metabolic health on an almost daily basis.

Another paper demonstrated similar results, and that authors explain that “a high false positive rate (low sensitivity) is problematic due to the psychological effect of a disease label and the burden and costs of repeated assessment, testing, and potentially unnecessary treatment. A high false negative rate (low specificity) is problematic when the disease is asymptomatic, serious, progresses quickly, and can be treated more effectively at early stages, or if the disease spreads easily from one person to another.

They go on to conclude that “metabolic conditions can be asymptomatic and serious, and thus, the extremely high false negative rate for using BMI as the test is problematic. By all measures, the BMI is an extremely poor test to be used as a basis for public health policy and clinical interventions.”


In their report “Changing the perfect picture: an inquiry into body image”, the Women and Equalities Committee (appointed by the house of commons) made it clear that “the use of the Body Mass Index (BMI) in determining if an individual’s weight is healthy should be scrapped immediately”.

After two years of expert testimony, they concluded that “BMI actually contributes to health issues such as eating disorders and people’s mental health by disrupting body image and inviting social stigmas”.

The use of BMI punishes people with larger bodies by denying them life-changing treatment, stigmatising them, and increasing their risk of mental health conditions including eating disorders. It also fails a large proportion of people in smaller bodies who are misled to believe that they are metabolically healthy when they are not. All this for a metric that is inaccurate at predicting health for the most part.

A weight-centric approach to healthcare is outdated and no longer supported by evidence. Not only does it fail to improve the health of patients and reduce their risk of disease longterm, it also causes harm. We need to adopt a weight inclusive approach to healthcare.

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Weight-centric Healthcare

The weight-centric approach is defined by Lily O’Hara and Jane Taylor as having the following 6 beliefs and assumptions:

  • weight is under individual control
  • weight gain is caused by an imbalance in caloric intake and energy usage
  • health status can be predicted by weight
  • excess body weight causes disease and early death
  • methods for successful long-term weight loss involve the modification of eating and exercise patterns
  • losing weight will result in better health

There is a wealth of research that addresses and refutes these assumptions. 

There are hundreds of factors that control our weight. Geneticists have isolated over 100 genes, and some argue that weight is similar to height in that it is predominantly controlled by our DNA. In addition, early childhood trauma impacts our neurochemistry and neurophysiology. It is associated with higher levels of stress hormones, which in turn impact weight. This suggests that our weight is pre-determined within the first few years of our lives.

There are a number of medical conditions and medications that influence weight. More and more evidence suggests that insulin resistance causes weight gain as opposed to the other way around. A number of medications clearly state that weight gain is a recognised side effect, and yet iatrogenic weight gain is still viewed as something that is under an individual’s control.

The small proportion of weight that is not determined by genetics, childhood experience, underlying physiology and/or medication, is predominantly controlled by external factors that are outside the individual’s control (such as social, economic and environmental ones). Nutrition and exercise play a relatively small role in weight control. 

The greatest risk factor for weight gain, is in fact weight loss. Dieting and weight cycling have been shown to increase overall weight in the long term. Whilst we do not know exactly how this happens, theories include chronic stress/allostatic load, disordered eating, and interfering with set point weight.

The first law of thermodynamics does not apply to the human body because it is not a closed system.  There are too many interfering factors (eg. gut biome). In their book “Health at Every Size“, Lindo Bacon discusses the evidence in detail and demonstrates that weight gain is not due to eating too much and/or not exercising enough.

Whilst nutritional status and physical activity have been shown to be relevant to our health, weight gain is not a result of being malnourished or sedentary. Furthermore, contrary to popular belief, there is very limited evidence linking dietary behaviours or physical activity to the environment.

Whilst there are known associations between weight and chronic health conditions, it is important to remember that association is not the same as causation. Unless we have enough evidence that weight gain causes a condition and that it is not down to chance or any other reasonable explanation, it is unsafe to use weight as a predictor of said condition.

It is important that we interpret evidence accurately, avoiding the epidemiological fallacy that population level results can be interpreted on an individual basis.

There is no evidence that overall health status can be confidently predicted by weight (see above).  Furthermore, the claim that life expectancy is reduced in people with higher than the ‘normal weight’ BMI is not actually supported by large epidemiological studies. In fact, many studies show that people with a BMI between 25-30 have the longest life expectancy, and one very large epidemiological study demonstrated that people with a BMI of 34-36 had a higher life expectancy than those with a BMI of 18-20.

In a  study of the “relationship between low cardiorespiratory fitness and mortality”, active fat people had half the cardiovascular disease mortality rates of sedentary people with a “healthy BMI”. This would suggest that asking about activity levels is a far more accurate predictor of cardiovascular health than weighing patients, irrespective of their size.

Whilst there are numerous studies showing associations between larger bodies and mortality, almost all of them fail to control for potential confounding factors including weight cycling, weight stigma, poverty, chronic stress, physical activity and diet history. All of these are also associated with increased adiposity, and are therefore essential to adjust for before interpreting the results of epidemiological studies. 

Type-2 diabetes is the condition with the strongest link to so-called “excess weight”. This is evident from a number of cross-sectional studies. However, twin studies have demonstrated that the etiology of diabetes is thought to be predominantly genetic. In 1989, epidemiologist Peter Bennett stated that “Insulin resistance may be the key defect that independently leads to ob*sity, hypertension, and diabetes, and accounts for the well-known associations among ob*sity, serum insulin levels and glucose intolerance. Insulin resistance, rather than ob*sity, may be the principal determinant of diabetes”. There has been a wealth of evidence since then that supports this theory.

Whilst there is a correlation between weight and a number of conditions at both ends of the u-shaped curve, there is a growing amount of evidence that ‘excess’ weight is protective against mortality and morbidity. This is known as the “ob*sity paradox” (although the term paradox implies that the link between ob*sity and illness is well demonstrated to begin with, which it is not).

The following conditions are seen less often in people in the ‘ob*se’ category than in the ‘healthy weight’ category:

  • Lung, stomach, colon and esophageal cancer
  • Malignant melanoma,
  • Pre-menopausal breast cancer
  • Chronic bronchitis
  • Tuberculosis
  • Mitral valve prolapse
  • Anemia
  • Type 1 diabetes
  • Premature menopause
  • Osteoporosis

Studies have also shown higher survival rates in people in the ‘ob*se’ category compared to those in the ‘healthy weight’ category in the following conditions:

Following a recent ischemic stroke, one study found that after adjusting for confounding factors, people in the ‘ov*rweight’ and ‘ob*se’ BMI categories had significantly lower risk of a major vascular event in the following 2½ years, compared with people in the ‘healthy weight’ BMI category.

In spite of all this evidence, we insist on advising people to lose weight after a cardiovascular event.

Whilst weight loss is usually possible soon after commencing a weight loss program, the vast majority of people will regain that weight within 2-5 years. In fact, studies show that up to 95% will regain the weight and between one third and two thirds of people will regain more then they lost within 5 years.

Multiple studies have demonstrated that weight loss is not only almost impossible for most people to maintain, but it strongly predicts weight gain.

Those that claim that long-term weight loss is possible, such as the national weight control registry, have been criticized for a number of reasons.

In their paper “Validity of claims made in weight management research”, Lucy Aphramor undertakes a narrative review of dietetic articles and calls into question the many false claims made by those that support weight management programs.

There are many studies that demonstrate an improvement in metabolic markers, symptoms and quality of life following weight loss. However, these studies usually don’t follow patients up beyond 6 months. Those that do often find patients relapse beyond 18 months.

For example, a literature review of the weight loss interventions for ob*se people with non-insulin-dependent Type-2 Diabetes showed initial improvements, but follow-up at 6 to 18 months actually showed a deterioration back to starting values, even when weight loss persisted. In spite of substantial average losses between 3-9kg, there was no apparent benefit to participants after 1 year. In fact, one study showed that diabetics were worse off a year after losing weight.

Another literature review found that weight loss diets led to minimal improvements in cholesterol, triglycerides, systolic and diastolic blood pressure, and fasting blood glucose, and that none of these correlated with weight lost. Similar results have been seen in long term studies following weight loss surgery.

In 2009, a global pandemic swept the world. Whilst it did not have anywhere near the same impact as COVID, Swine Flu (H1N1) caused a number of deaths from a flu-like respiratory illness.  At the time, it was well documented that people with larger bodies had worse outcomes and higher mortality rates than those with smaller bodies.

Severn years later, a literature review was published that confirmed that there was a link between H1N1 infection and ob*sity. However, there was also a link between ob*sity and delayed treatment. Once they adjusted for this delayed treatment, the association between H1N1 deaths and ob*sity disappeared.

This has profound implications for the medical profession. The paper was not able to identify why there was a delay. But it is a question that we all need to be asking ourselves. Was it doctor bias? Did doctors treat their thin patients in preference to those with larger bodies?

Was it inequalities in healthcare? Were those with larger bodies simply less able to access the care that they needed? Or were they afraid of medical professionals because they had been repeatedly stigmatised in the past?

These questions are even more relevant in light of the recent COVID pandemic, in which we were repeatedly told that ITUs were filled with fat patients and that the risk of hospitalisation, ventilation and death was much higher in those with higher BMIs.

Weight stigma causes poorer health outcomes.  It leads to discrimination on the part of the medical community resulting in disparities in healthcare, and it damages the patient-practitioner relationship resulting in avoidance of medical professionals.

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Weight Stigma

The term weight (anti-fat) bias describes the negative weight-related attitudes, beliefs, assumptions and judgements in society that are held about people with larger bodies. Weight stigma is the manifestation of weight bias through harmful social stereotypes that are associated with people with larger bodies. Weight based (anti-fat) discrimination is the unjust treatment of individuals with larger bodies because of their weight.

Medical weight stigma is particularly traumatising for two main reasons. One is that medical professionals hold a unique place of authority rendering most patients unable to advocate for themselves when needed. The second is that health is arguably one of the most important priorities for most people, and patients see medical professionals as the gatekeepers of their healthcare.

There are numerous studies that highlight how weight bias impacts the way that medical professionals treat their patients. One article reviews up to date literature from a number of disciplines to build a picture that every medical professional should read.

The authors of the study found that “many healthcare providers hold strong negative attitudes and stereotypes about people with ob*sity. There is considerable evidence that such attitudes influence person-perceptions, judgment, interpersonal behaviour and decision-making. These attitudes may impact the care they provide.”

Whether it impacts the management plan, the time that is spent with patients, a lack of respect or poorer levels of communication, the  difference in the way medical professionals treat their fat patients is causing stark inequalities in healthcare.

Domain 4 of the GMC Good Medical Practice states that doctors should “treat patients and colleagues fairly and without discrimination”. Failure to do so must be addressed.

A study of 4732 medical students found that 75% of them demonstrated implicit anti-fat bias and two thirds of them demonstrated explicit anti-fat bias. “Explicit attitudes were more negative toward ob*se people than toward racial minorities, gays, lesbians, and poor people”.

Weight stigma impacts a person’s ability to trust their medical professional. Not only does it damage the relationship with individual practitioners but it also impacts how people view the medical profession as a whole.

Weight stigma causes people to experience a high level of stress during a healthcare visit, which can lead to temporary impairment of cognition and a reduced ability to effectively communicate.

Weight stigma can cause a person to discount feedback provided by medical professionals, which in turn can reduce adherence.

Weight stigma causes people to avoid clinical care if they fear that their body weight will be a source of shame, embarrassment, humiliation, gaslighting or abuse. This includes avoidance of cancer screening, long term condition follow ups and urgent/acute care.

Tomiyama et al write that “weight stigma is harmful to health, over and above objective body mass index”. They go on to say that “weight stigma is prospectively related to heightened mortality and other chronic diseases and conditions” and also “heightens the risk of ob*sity through multiple ob*sogenic pathways”. 

Furthermore, “weight stigma is particularly prevalent and detrimental in healthcare settings, with documented high levels of ‘anti-fat’ bias in healthcare providers, patients with ob*sity receiving poorer care and having worse outcomes, and medical students with ob*sity reporting high levels of alcohol and substance use to cope with internalized weight stigma.” 

Weight stigma (which is experienced in all areas of life) causes exposure to high levels of stress hormones and increases allostatic load. There is growing evidence to suggest that this has significant impact on long-term physiological health, including heart disease, stroke, cancer and mental health conditions.

In fact, internalized weight stigma may provide an alternative explanation for the association between ob*sity and chronic disease.

When healthcare professionals stigmatise their patients, they are causing long term harm and may be responsible for the increased levels of chronic health conditions seen in the very people they are supposed to be helping.

(This list is by no means exhaustive)

  • Lack of equipment suitable for people with larger bodies (including gowns, BP cuffs, chairs, beds etc)
  • Stigmatising posters/images in the waiting room or information leaflets
  • Weighing people unnecessarily or at inappropriate times
  • Providing unsolicited weight loss advice
  • Denying a patient an examination/investigation/referral because their conditions is perceived to be caused by weight right from the beginning
  • Celebrating weight loss with a patient 
  • Ignoring unintentional weight loss
  • Prescribing weight loss instead of treating everyone the same, irrespective of size and body shape

The only people who appear to benefit from weight loss are those who are financially profiting from it. Prescribing weight loss directly harms patients and increases their risks of poorer health outcomes. Instead of working in the best interests of our patients, we are working against them. We have become part of the problem, not part of the solution.

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Weight Loss Prescriptions

Whilst the average population weight has increased since the 1980s, it began to level off around the turn of the 21st century. Claims that ob*sity rates have doubled and even tripled are gross exaggerations of the fact that the majority of people are only 3-5kg heavier than they were a generation ago.

In fact, emotive language such as ‘epidemic’, ‘war’ and ‘crisis’ are purposely misleading and are possible primarily due to the arbitrary cutoffs for the the different BMI categories, bearing in mind that these changed suddenly in 1998 rendering millions of people ‘overw*ight’ or ‘ob*se’ overnight.

Weight management programs have little to no long term benefits according to several experts including Glenn Gaesser, Julie Guthman, and Gina Kolata.

The evidence that does demonstrate any benefit is usually littered with flaws including small sample sizes, statistical inconsistencies, large losses to follow up and no long term data beyond 2 years (when the majority of weight regain tends to occur).

Intentional weight loss is a well known risk factor for disordered eating and eating disorders. Ob*sity prevention strategies have been found to increase the risk of eating disorders in adolescents. Eating disorders are associated with extremely poor health outcomes, irrespective of weight, and anorexia has the highest mortality rate of any mental health condition.

A very small minority of people with eating disorders will have a BMI <18. The vast majority have larger bodies and are repeatedly failed by the healthcare system.

Repeated attempts at weight loss with intermittent periods of weight gain is known as weight cycling or yo-yo dieting. This is known to be an independent risk factor for a number of health conditions. For example, the increase in cardiovascular disease in ob*se patients seen in the Framingham study disappears when you adjust for weight cycling. People with larger bodies who maintained a high but steady weight had an average risk of death or cardiovascular disease.

There is growing evidence that weight stigma causes both physiological and pyschological harm. It has been linked to hypertension, type 2 Diabetes, metabolic syndrome, Allostatic load, cortisol reactivity, and oxidative stress. In a study on medical students, perceived and/or internalized weight stigma was associated with poorer health and wellbeing. It was found to increase rates of depression, anxiety and low self-esteem, and these findings have been replicated in several studies.

As many experts have suggested, the major health crises experienced by the vast majority of people are not down to poor diet or lack of physical activity, but for more systemic issues such as violence, prejudice, corrupt capitalism, and social isolation. It would seem that the main beneficiaries of weight management programs are those that financially benefit from them.

Is it any wonder that the diet and wellness industrial complex invests millions into anti-ob*sity campaigns and funds organisations such as the All Party Parliamentary Group on ob*sity? Is it any wonder that in response to the Women and Equalites Committee’s advice to scrap BMI, the government announced further investment into weight management programs and began the process of financially incentivising GPs to refer their patients into the service?

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Chose Weight Inclusive Care

Whether you're a healthcare professional looking to improve their practice, or a patient who wants help to fight against medical weight stigma, be sure to take advantage of our resources and links.

Further reading

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