Although overweight and obesity are increasing in prevalence, eating disorders such as anorexia nervosa, bulimia nervosa and binge-eating disorder are simultaneously on the rise. It is important to address the burden of disease of overweight and obesity on the population, yet there is concern that some of these efforts may be encouraging unhealthy weight control behaviours (UWCB). Using an online survey, 137 participants were exposed to four anti-obesity public health advertisements presented in random order. Weight satisfaction, shape satisfaction, desire to control weight, desire to control shape and desire to engage in UWCB were measured on a 100-point visual analogue scale. A significant effect of the experimental condition was found after exposure to Image 1 with a decrease in weight satisfaction, and increased desire to control body weight, body shape and engage in UWCB. Mean scores for UWCB also increased, on average, across all four image conditions. Public health advertisements targeting obesity risk encouraging unhealthy weight control and subsequent disordered eating behaviours. Those responsible for the implementation of such advertisements must consider very carefully the potential to cause unintended harm.