There is evidence that obesity is a risk to health and longevity of life. This is the first paper to use crosscountry data to analyze the effect of obesity levels on life expectancy, the trade-off between health expenditure and obesity levels, and differential effect of obesity on genders. We develop a conceptual model and empirically test it using a panel data of 183 countries for the years 2007 - 2014. The life expectancy and obesity national data provides us a vantage point of the world food situation. The theory and the empirical results suggest that average life expectancy is a concave function of average obesity and indicate that low obesity levels on average are indicators of existence of undernutrition. We find that while obesity is a major problem- its impact on life expectancy is mostly mitigated by medical expenditure in developed countries, undernutrition and lack of medical expenditure in developing countries is even a more severe problem. This is because the marginal benefit of medical expenditure in a low obesity country (implying undernutrition) has larger impact on life expectancy than medical expenditure in country with high obesity country.