On January 20, I joined the ranks of those who've sacrificed themselves for science: I started one of those "low-carb" diets. So far, the sacrifice has been worth it.
I'd always resisted celebrity-sponsored diets, smugly thinking my background in genetics and biochemistry made me more of an authority on matters nutritional than the likes of Whoopi Goldberg and Sarah Ferguson. I've even taught the subject.
But this low-carb diet is different. It prescribes "good carbs and good fats" while blacking out most things white and processed, including rice, bread, pasta, and potatoes. Building on conventional wisdom about the evils of excess starch, this program also considers insulin swings.
A new way of viewing carbohydrates began in 1981, when a University of Toronto team measured the glycemic index (GI) for many foods. The GI is a measure of the speed at which foods hike blood glucose and therefore insulin secretion, averaged...