Flawed science 1977 Dietary Guidelines promoted a reduction in fat consumption, which permitted an increase in carbohydrate consumption. The shift from natural food containing animal products and fats resulted in an increase in processed food consumption rich in carbohydrates, processed grains, and industrial seed oils.
In the United States between 1961-2011, 90% of the increased calorie intake has come from carbohydrates and polyunsaturated vegetable oils.