In the 1950s, coronary heart disease emerged as a leading cause of death. Scientists searched for reasons to explain this phenomenon, and one hypothesis suggested that the increase in heart disease might be related to the cholesterol levels in our blood. A theory was soon advanced that increased consumption of animal fat raised our cholesterol levels and resulted in heart disease. The link between cholesterol, saturated fat, and heart disease was, however, only associative, and completely ignored the fact that some populations with diets high in animals fats don’t have high rates of heart disease. For example, 50 percent of the calories in Inuit native foods come from the fats of wild animals, and their cardiac death rate is around half of that in North America.

The United Nations reported in the year 2000 that the number of people suffering from over nutrition, at 1 billion, had officially surpassed the number suffering from malnutrition (800 million). We might, then, have reduced our intake of animal fats, but at the same time the amount of fat in our diet has actually increased, being replaced by man-made hydrogenated fats, full of trans fats. These trans fats are difficult for our body to process, so instead our body stores them as fat. Once considered a sign of excess and a high-income problem, over nutrition is now on the rise in low and middle income countries, particularly within urban settings.