As obesity continues to rise in the U.S., the presence of weight bias and stigma become a growing concern for not only the individuals experiencing it, but the healthcare professionals trying to treat their patients. Identifying why weight bias occurs is an important factor in putting an end to the stigmatizing behavior, so everyone affected by excess weight and obesity can get the treatment they need — and not be afraid to do so.

In this series, Dr. Sean Phelan, PhD, discusses his research at the Mayo Clinic about weight bias and how it impacts patients, medical students and the relationship between healthcare professionals and those who they are treating.

In this study, we were interested in finding out how medical students’ attitudes change during medical school, and whether there was anything the school was doing that might have influenced their changing perspectives.  We sampled students from 49 medical schools across the U.S. and measured their attitudes in their first semester and their last semester of school.  We focused on attitudes about three stigmatized groups, racial minorities, gays and lesbians, and people with obesity.

In the research outlined in “The Mixed Impact of Medical School on Medical Students’ Implicit and Explicit Weight Bias,” we concentrated on two types of attitudes about people with obesity: explicit bias and implicit bias. Explicit bias is a self-reported preference for one group over another. Implicit bias, on the other hand, occurs unconsciously. These are the extremely quick, automatic connections that we make in our brain when we see someone or something, without thinking about it.

We must consider both types of thinking, because the connection between the two is weak. People who have no conscious weight bias may, due to a lifetime of observing media images, discrimination, teasing and other types of stigma, still unconsciously be biased against people with obesity.

It is important to study implicit bias in health care because it has its strongest influence on our behavior when we are overworked, tired, and don’t have the brain capacity to carefully think things through. Being overworked and tired describes most medical students and physicians, so we believe that implicit bias may have a strong influence in situations in the health care setting.

During the last semester of the students we studied, we asked a lot of questions about their experiences in medical school.  We used questions in three broad categories that we hypothesized would influence changes in bias: curriculum, role modeling and contact.


We asked how many hours of training students had in situations in the healthcare setting with disparities, or in implicit bias, or in how to deal with a “difficult patient,” and how skilled they were in dealing with patients with obesity, among other things.

Role Modeling

We asked how often students had overheard faculty, attending physicians or residents make negative or derogatory comments about patients with obesity and how often they had seen a health care provider discriminate against a person with obesity.


We asked students how often they interacted with faculty members, peers, or patients affected by obesity, and how favorable they felt about those interactions.

When we looked for associations between these experiences and change in weight bias, we found that several of them were associated with increased or decreased bias during medical school.

  1. The number of hours spent training in how to deal with difficult patients was associated with increased implicit bias. This may be due the process of “othering,” or defining a certain groups as being different or odd.  Because people with obesity are often perceived as unwilling to make behavior changes to lose weight, they can be labeled “difficult,” and this might have influenced the students’ attitudes.
  2. Students who felt more skilled at counseling patients to lose weight had attitudes that improved over medical school. This points to the lack of training students receive in weight-loss counseling, especially in counseling strategies that are considered patient-centered, and how increasing training and comfort in providing this type of care may improve doctors’ overall attitudes about patients with obesity.
  3. Contact with patients stood out in one way: students who had more favorable interactions with patients with obesity developed more positive implicit and explicit attitudes about people with obesity. Perhaps increasing the opportunities for students to have positive care experiences with patients with obesity could reduce bias.
  4. Students who more frequently observed faculty members, attending physicians or residents make negative or derogatory comments about or discriminate against patients with obesity was found to be associated with worsened implicit and explicit bias. This points to the strong influence of role-modeling in perpetuating weight bias, and the possibility that eliminating negative comments about patients with obesity — whether those patients can overhear or not, could help reduce the bias of new physicians.

Another interesting finding in our research was the lack of association with training in health disparities or provider bias. This could be because very few, if any, medical schools include weight bias as part of their curriculum. People with obesity are not considered a “population with health disparities,” but given the evidence of disparities in the quality of care and disease outcomes for individuals affected by the disease, such a distinction would draw important attention to the issue of weight bias.

On average, students’ implicit biases improved, and explicit biases became worse over medical school. We don’t know the reasons for this. It does not correlate with changes in attitudes in the general public over that same time. One possible explanation has to do with the way that interacting with people affects our attitudes about them or people like them. Positive interaction experiences tend to reduce bias, especially if those interactions involve the sharing of ideas or working together towards a common goal.

Some research has found that the effect of positive contact on implicit bias is direct, whereas the effect on explicit bias depends on whether anxiety about future encounters decreased.  Perhaps in medical school, there is so much anxiety over treating obesity with little training in how to do so, it overshadows the impact of positive interactions that medical professionals have with patients affected by excess weight and obesity.

Medical schools have a responsibility to graduate new physicians who are ready to provide the highest quality care to all patients. Unfortunately, we know that unfair treatment exists, and for people with obesity, as a strongly stigmatized group who are often blamed for their disease, may experience lower quality and less-patient-centered care, unless we can intervene to reduce weight bias in the next generation of health care providers.

About the Author:

Dr. Sean M. Phelan is an Assistant Professor of Health Services Research at the Mayo Clinic in Rochester, MN. Dr. Phelan is a core faculty member in the Mayo Research Program on Equity and Inclusion in Healthcare, where his research program is focused on reducing health disparities and improving health care quality and outcomes for patients with obesity, as well as patients from other stigmatized and marginalized groups. He is also a consultant on diversity and equity issues with Partners in Equity and Inclusion. Dr. Phelan can be reached at [email protected] or [email protected].