Implicit and explicit weight bias in a national sample of 4,732 medical students: the medical student CHANGES study

Abstract

Objective: To examine the magnitude of explicit and implicit weight biases compared to biases against other groups; and identify student factors predicting bias in a large national sample of medical students.

Methods: A web-based survey was completed by 4,732 1st year medical students from 49 medical schools as part of a longitudinal study of medical education. The survey included a validated measure of implicit weight bias, the implicit association test, and 2 measures of explicit bias: a feeling thermometer and the anti-fat attitudes test.

Results: A majority of students exhibited implicit (74%) and explicit (67%) weight bias. Implicit weight bias scores were comparable to reported bias against racial minorities. Explicit attitudes were more negative toward obese people than toward racial minorities, gays, lesbians, and poor people. In multivariate regression models, implicit and explicit weight bias was predicted by lower BMI, male sex, and non-Black race. Either implicit or explicit bias was also predicted by age, SES, country of birth, and specialty choice.

Conclusions: Implicit and explicit weight bias is common among 1st year medical students, and varies across student factors. Future research should assess implications of biases and test interventions to reduce their impact.

Figure 1

Flowchart showing ascertainment strategies and number of participants enrolled with each strategy

Figure 2. Distribution of explicit and implicit weight bias in a national sample of medical students

An IAT score ≥ .65 was considered strong; a score < .65 and ≥ .35, moderate; and a score <.35 and ≥.15, slight anti-fat bias. A score > −.15 and <.15 was considered no bias, and a score ≤ −.15 was considered pro-fat bias. For explicit bias, a difference between feeling thermometer scores for Whites and obese people > 15 was considered strong; a difference between 6 and 15, moderate; and difference between 1 and 5, slight anti-fat bias. A difference of 0 was no bias, and a difference < 0 was pro-fat bias.

Figure 3. Explicit bias against people who are obese and other stigmatized/minority groups relative to Whites

The dots represent the sample mean of each participant’s rating of whites minus their rating of obese people on feeling thermometers. Higher numbers indicate lower warmth toward the group relative to Whites. The bars represent the 95% confidence intervals