Lev Radin/Pacific Press/LightRocket via Getty Images Harvard nutrition expert Dr. Walter Willett has been studying how the foods people eat impacts their long-term health for over 30 years. He says his own diet is "moderately low-carbohydrate," and he never drinks sugar-sweetened beverages. His go-to breakfast combo is a high-fat, high-carbohydrate combination of oats, nuts, and […]