"While it’s easy to believe that we remain lean because we’re virtuous and we get fat because we lack self-control or discipline, the evidence clearly says otherwise.
Not all foods containing carbs are equally fattening. The most fattening foods are those that have the greatest impact on our insulin and blood sugar levels. These are the easily digestible carbs. Anything made of refined flour (bread, cereals, and pasta), starches (potatoes, rice, and corn), and liquids (beer, pop, fruit juice). “These foods,” says Taubes, “flood the bloodstream quickly with glucose. Blood sugar shoots up; insulin shoots up; We get fatter.”"
Why We Get Fat: And What to Do About It - Farnham Street