Using a national cross-sectional survey of 500 primary care physicians conducted between 9 February and 1 March 2011, the objective of this study was to assess the impact of physician BMI on obesity care, physician self-efficacy, perceptions of role-modeling weight-related health behaviors, and perceptions of patient trust in weight loss advice. We found that physicians with normal BMI were more likely to engage their obese patients in weight loss discussions as compared to overweight/obese physicians (30% vs. 18%, P = 0.010). Physicians with normal BMI had greater confidence in their ability to provide diet (53% vs. 37%, P = 0.002) and exercise counseling (56% vs. 38%, P = 0.001) to their obese patients. A higher percentage of normal BMI physicians believed that overweight/obese patients would be less likely to trust weight loss advice from overweight/obese doctors (80% vs. 69%, P = 0.02). Physicians in the normal BMI category were more likely to believe that physicians should model healthy weight-related behaviors-maintaining a healthy weight (72% vs. 56%, P = 0.002) and exercising regularly (73% vs. 57%, P = 0.001). The probability of a physician recording an obesity diagnosis (93% vs. 7%, P < 0.001) or initiating a weight loss conversation (89% vs. 11%, P ≤ 0.001) with their obese patients was higher when the physicians' perception of the patients' body weight met or exceeded their own personal body weight. These results suggest that more normal weight physicians provided recommended obesity care to their patients and felt confident doing so.