Diet

An unhealthy diet is a major risk factor for chronic diseases such as cardiovascular diseases, cancer, diabetes, and conditions related to obesity. In the 20th century, the average American diet shifted from one based on fresh, minimally processed vegetable foods to one based on animal products and highly refined, processed foods, leading to an increased consumption of calories, fat, cholesterol, refined sugar, animal protein, sodium, and alcohol and far less fiber and starch than was healthful. As a result, more than one third of US adults are obese, with an estimated medical cost of $147 billion. Physicians have an important role in educating patients about healthful nutrition and in providing dietary guidelines. This module discusses the role of energy in weight loss; the structure of fat and cholesterol, their effects on blood lipid levels and cardiovascular risk, and related dietary recommendations; carbohydrates; dietary fiber; proteins; vitamin and mineral consumption; water and food consumption; and the relationship between diet and health. Tables review the principles of a healthy diet; recommended daily intake of fat and other nutrients; types of dietary fiber and represe