Insulin also influences an enzyme called hormone-sensitive lipase, or HSL. And this, says Taubes, "may be even mroe critical to how insulin regulates the amount of fat we store. Just as LPL works to make fat cells (and us) fatter, HSL works to make at cells (and us) leaner. It does so by working inside the fat cells to break down triglycerides into their component fatty acids, so that those fatty acids can then escape into the circulation.
The more active this HSL, the more fat we liberate and can burn from fuel and the less, obviously, we store. Insulin also surpresses this enzyme HSL and so it prevents triglycerides from being broken down inside the fat cells to a minimum." This also helps explain why diabetics often get fatter when they take insulin therapy.
Carbohydrates primarily determine the insulin level in the blood. Here quantity and quality are important. Carbs ultimately determine how fat we get. But most people eat carbs so why are some fatter than others? We all naturally secrete a different level of insulin -- given the same food people will secrete different levels of insulin. Another factor is how sensitive your cells are to insulin and how quickly they become insensitive.
The more insulin you secrete—naturally or with carbohydrate rich foods—the more likely it is that your body becomes insulin resistant. The result is a vicious circle.
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."
