Harvard professor Daniel Lieberman's Fed Up explores why fad diets fail

Harvard professor Daniel Lieberman's book "Fed Up" argues diets rarely work long-term because biological and evolutionary factors resist weight loss, and weight is not a reliable health indicator. Lieberman, a biological sciences professor, and his wife tested several fad diets over two weeks. He explains losing weight isn't simply the opposite of gaining weight, and challenges assumptions about "weight problems" and stigma around fat. Drawing on evolutionary biology, Lieberman uses a simple "food in, babies out" formula to explain dietary habits. Despite dense science, the accessible writing may inspire readers to scrutinize their own diets.