They fear its emphasis on substituting high-carbohydrate foods for fats may actually be contributing to the epidemic of obesity sweeping the nation. The pyramid advises people to build their whole diet on a foundation of bread, grains and other high-carbohydrate food. Lots of carbos, it says, are good. Fats are bad. It illustrates that idea by placing fats, oils and meats near the narrow peak.
Carbohydrates make up the broad base.
Fruits and vegetables are in between. Scientists once assumed that all carbohydrates released sugar units at the same rate. Now they know that carbohydrates break down at different rates. White bread and potatoes release glucose quickly. Baked potatoes actually have a higher glycemic index than pure sugar.