<P> By contrast, a healthy diet has higher proportions of fruits, nuts, vegetables, whole - grain foods, poultry, and fish . </P> <P> This diet is "rich in red meat, dairy products, processed and artificially sweetened foods, and salt, with minimal intake of fruits, vegetables, fish, legumes, and whole grains ." Various foods and food processing procedures that had been introduced during the Neolithic and Industrial Periods had fundamentally altered 7 nutritional characteristics of ancestral hominin diets: glycemic load, fatty acid composition, macronutrient composition, micronutrient density, acid - base balance, sodium - potassium ratio, and fiber content . </P> <P> The typical American diet is about 50% carbohydrate, 15% protein, and 35% fat . These macronutrient intakes fall within the Acceptable Macronutrient Distribution Ranges (AMDR) for adults identified by the Food and Nutrition Board of the United States Institute of Medicine as "associated with reduced risk of chronic diseases while providing adequate intakes of essential nutrients," which are 45 - 65% carbohydrate, 10 - 35% protein, and 20 - 35% fat as a percentage of total energy . However, the nutritional quality of the specific foods comprising those macronutrients is often poor, as with the "Western" pattern discussed above . Complex carbohydrates such as starch are believed to be more healthy than the sugar so frequently consumed in the Standard American Diet . </P> <P> A review of eating habits in the United States in 2004 found that about 75% of restaurant meals were from fast - food restaurants . Nearly half of the meals ordered from a menu were hamburger, French fries, or poultry--and about one third of orders included a carbonated beverage drink . From 1970 to 2008, the per capita consumption of calories increased by nearly one - quarter in the United States and about 10% of all calories were from high - fructose corn syrup . </P>

A majority of calories in the average american diet come from what macronutrient