<P> It is not just the total amount of calories that matters but specific nutritional deficiencies such as vitamin A deficiency, iron deficiency or zinc deficiency can also increase risk of death . </P> <P> Overnutrition caused by overeating is also a form of malnutrition . In the United States, more than half of all adults are now overweight--a condition that, like hunger, increases susceptibility to disease and disability, reduces worker productivity, and lowers life expectancy . Overeating is much more common in the United States, where for the majority of people, access to food is not an issue . Many parts of the world have access to a surplus of non-nutritious food, in addition to increased sedentary lifestyles . Yale psychologist Kelly Brownell calls this a "toxic food environment" where fat and sugar laden foods have taken precedence over healthy nutritious foods . </P> <P> The issue in these developed countries is choosing the right kind of food . More fast food is consumed per capita in the United States than in any other country . The reason for this mass consumption of fast food is its affordability and accessibility . Often fast food, low in cost and nutrition, is high in calories and heavily promoted . When these eating habits are combined with increasingly urbanized, automated, and more sedentary lifestyles, it becomes clear why weight gain is difficult to avoid . </P> <P> Not only does obesity occur in developed countries, problems are also occurring in developing countries in areas where income is on the rise . Overeating is also a problem in countries where hunger and poverty persist . In China, consumption of high - fat foods has increased while consumption of rice and other goods has decreased . </P>

In developed countries the major cause of malnutrition is