Is your doctor a fattist?

“Doctors are ‘prejudiced’ against overweight patients (and men are worse than women)”, the Daily Mail reported today.

This story is based on a survey that aimed to examine US doctors’ conscious and unconscious feelings about weight.

Explicit (conscious) feelings were judged by a direct question. More importantly, implicit (unconscious) feelings were judged by a web-based series of tests. Studying implicit feelings is arguably more important as many people may have deep-seated opinions, which, for reasons for social pressure, they are unwilling to admit to others (and possibly themselves).

The researchers found that the doctors had both a strong implicit and explicit preference for thin people rather than fat ones. However, it is important to note that their attitudes were similar to those found among the general public.

This a voluntary survey, so doctors who chose to take part may be more, or less, biased against overweight people than the rest of the population. The researchers also offer no information about what could be causing the bias against bigger people. For example, the researchers didn’t explore whether doctors may feel frustrated with overweight people for health reasons, or alternatively they are not immune to cultural trends changing our perception of weight and body image issues.

These experimental findings do not necessarily imply that the views of those doctors surveyed would have any negative impact on the care that they would give overweight or obese people. However, as it is crucial that the attitudes of health professionals involved in treating obese and overweight patients are not influenced by personal views, this may be an issue that could be further explored in a UK study.

Where did the story come from?

The study was carried out by researchers at the University of Washington, University of Virginia, and the University of Modena and Reggio Emilia. It was funded by Project Implicit Inc, a non-profit organisation which aims to develop methods for investigating unconscious bias based on factors such as race, age, gender, or weight. The study was published in the peer-reviewed open access journal PLOS ONE.

The Daily Mail’s coverage was fair but failed to explain that the study was based on a non-representative survey. Also, the headlines could be interpreted to mean that doctors are prejudiced in terms of the actual patient care that they deliver, and this has not been studied. They also fail to explain that the detected bias was no different from that of the general population tested.

What kind of research was this?

This research took the form of a survey that looked at conscious and unconscious attitudes towards weight among a large group of US doctors. The researchers point out that more than a third of US adults are overweight and a similar proportion obese, yet many doctors feel unqualified to treat the problem. The researchers highlight previous studies which have suggested that doctors are biased against obese patients, with overweight patients also reporting disrespectful treatment.

The researchers say that biases may be both conscious (explicit) or unconscious (implicit), and it is possible that an unconscious bias against overweight people leads to poor quality care. Though the theory that unconscious bias may lead to poor quality care has not been assessed by the researchers.

The important limitations to this study design are that it was a voluntary internet survey about implicit weight views.

As such, the fact that included doctors have ‘self-selected’ to take part means they may not be representative of all doctors. Making a decision to spend time taking a test that takes around 10-15 minutes to complete may mean that they have stronger opinions about obesity (or conversely, some of the doctors may be more sensitive to the problems faced by obese people).

What did the research involve?

Between 2006 and 2010, members of the public accessed a public website called Project Implicit (https://implicit.harvard.edu) and chose to take a test developed by researchers aimed at assessing attitudes towards weight, called the Weight Implicit Association Test (IAT). 

The test uses a novel approach where participants are asked to quickly categorise silhouette images of people, using a computer keyboard, into a left column (thin) or a right column (fat). This is followed by a similar exercise to categorise value-laden words (such as joy, pleasure, pain, hate) into ‘good’ and ‘bad’ words.

Another round combines images of thin people associated with good words and fat people associated with bad words. A further round swaps this – with thin images being associated with ‘bad’ words and fat images associated with ‘good’ words.

The researchers consider that the delay in the time it takes in people correctly assigning a good word to the ‘fat column’ can determine levels of implicit bias. This is because people with an unconscious bias against fat people will take a slightly longer time to make the mental association between ‘fatness’ and ‘goodness’ (although this delay is just a fraction of a second).

Participants’ conscious attitudes towards weight were also examined. They were asked to endorse one of seven explicit statements reflecting their feelings in this area and the strength of those preferences. These ranged from “I strongly prefer thin people to fat people” to “I strongly prefer fat people to thin people”.

Participants were asked about their:

  • age
  • gender
  • race
  • ethnicity
  • height and weight
  • country of residence
  • level of education

Those who were medical doctors were identified through their self-reported level of education. The body mass index (BMI) of all participants was calculated from their height and weight. Researchers analysed overall attitudes and also the attitudes of the sub-sample of doctors, using statistical techniques.

What were the basic results?

There were 359,261 participants in the survey, of whom 2,284 had qualified as medical doctors. Among the doctors, 55% were women, 78% reported themselves as white, and 62% had a normal BMI.

The researchers found that:

  • overall, all members of the public who took the test showed a strong unconscious (implicit) anti-fat bias
  • on average, doctors also showed a strong unconscious (implicit) anti-fat bias
  • all test-takers, including the doctors’ sub-sample, reported a strong conscious (explicit) preference for thin people rather than fat people
  • among women participants overall, and among women doctors, the unconscious anti-fat bias was significantly weaker than for men
  • among doctors, the implicit anti-fat bias was strong among underweight, normal and overweight doctors
  • among doctors classified as obese, the unconscious anti-fat bias was only “moderate”

How did the researchers interpret the results?

The researchers conclude that strong unconscious and conscious anti-fat bias is as pervasive among doctors as it is among the general public. They say that an important area for future research is to investigate the association between doctors’ implicit and explicit attitudes about weight, patient reports of weight discrimination in health care, and quality of care delivered to overweight patients.


The personal attitudes of doctors and other health professionals towards obesity and the overweight is an important topic.

Overall, this US survey suggests that the views of medical doctors towards obesity and the overweight reflect attitudes in American society generally. The researchers cite previous studies which found that both doctors and members of the public tended to have negative feelings towards overweight and obese people.

However, it should be pointed out that this was not a scientific study that recruited participants on a representative basis. The analysis is based on a website survey to which some members of the public, including doctors, chose to respond. As such, it is affected by what is known as selection bias  – people who choose to take part may not be representative of the population at large.

As the people who took part in the survey knew it was about attitudes towards weight, it is possible that those who chose to take part may be less or more biased about weight than a representative sample of the population. Also, the survey relied on people self-reporting factors such as education, which could affect the reliability of its findings. It did not assess whether people who had qualified as doctors were practising, or in which field of medicine they were in.

Only US doctors were surveyed and their views may not directly reflect attitudes towards weight in the UK.

Finally, the findings do not necessarily imply that the views of those doctors surveyed would have any negative impact on the quality of care that they would give towards overweight or obese people.

However, the question of whether implicit bias (not just against overweight people, but in other clear differences such as age, gender or ethnicity) could adversely affect patient care, is an interesting one that deserves further study.

NHS Attribution