The obesity crisis is one of the largest public health challenges of the 21st century. Population-level adiposity has increased dramatically in recent times, and people not recognizing that they have overweight or obesity is now common. It has been widely assumed that not recognizing oneself as having overweight is detrimental to weight management and long-term health. Here, diverse research is reviewed that converges on the counterintuitive conclusion that not recognizing oneself as having overweight is actually associated with more favourable physical and mental health outcomes than recognizing oneself as having overweight. Drawing on existing models in social psychology and weight stigma research, an explanatory model of the health effects of self-perception of overweight is outlined. This model proposes that self-perception of overweight triggers social rejection concerns and the internalization of weight stigma, which in turn induce psychological distress and negatively impact health-promoting lifestyle behaviours. How self-perception of overweight may in part explain progression from overweight to obesity, and the public health implications of self-perception of overweight and obesity are also discussed.