'Why are we losing the war against obesity and chronic disease?' This is the simple question Peter Gluckman and Mark Hanson ask, exploring the dominant myth that the exploding epidemic of obesity, heart disease, and diabetes can be tackled by focusing on adult life styles. Addressing the flawed approach of the weight-loss industry, they explain why a continued focus simply on diet and exercise will fail. Highlighting the implications of the growing burden of these problems in the developing world, they show that the scientific enterprise ignores the reality of the social, cultural, and biological determinants that make different populations and people respond differently to living in the modern nutritionally rich world. Gluckman and Hanson review the overwhelming scientific evidence that much of the problem emerges in early life and even before birth, identifying that to address these issues requires considering development in two dimensions - a life course approach and addressing the developmental challenges of countries emerging through the socioeconomic transition. Asking why the major global bodies and vested interests fail to consider these dimensions and continue with failed approaches, they conclude by discussing the complex interactions between health and the food industry, and suggest that the food industry must be co-opted as an ally in this battle, providing a clear pathway forward.