“When you enter into the science of obesity, it resembles more the realm of religious belief rather than science,” writes science writer Gary Taubes. In this course we review accurately the actual science on weight loss attempts, beginning with the three meta-analyses which summarize the effects of all previously published clinical trials. All three reached the same conclusion: It is medically unethical to advise a patient to restrict calories in order to lose weight. Unethical because it is well established in repeated trials that such attempts provide no benefit to health, that those who diet, when followed long term, gain more weight than those who do nothing. On the other hand dieting readily causes metabolic and psychological injury.