despite being very different of diets that include different types of food containing different levels of biomolecules, these diets are all able to support human being in living. How is this possible?

As nutrients, protein is overemphasized and carbohydrates are underrated in terms of their importance in our diets. Most people in the United States now eat more protein than their bodies need, and, somehow, carbohydrate-rich foods such as potatoes and bread have gotten a bad name for being fattening. Yet protein from animal sources often comes in foods that contain significant amounts of saturated fatty acids. And the only carbohydrate-rich foods that are truly fattening are those laden with fats and added sugar, such as pastries, cookies, and baked potatoes heaped with sour cream.

In fact, there is some evidence that diets high in carbohydrates may help reduce the risk of heart disease. Thus the Eat for Life guidelines suggest not to eat any more protein than you already do and to increase the amount of carbohydrates you eat to compensate for the lower amount of fat that your diet will contain.

This chapter presents the evidence that increasing the proportion of carbohydrates in the usual American eating pattern at the expense of fat will tend to lower chronic disease risk. It also discusses some of the health claims made for dietary fiber, a group of substances that are made up mostly of complex carbohydrates.

the answers are a and c