Earlier this year, the Food and Drug Administration approved a new weight-loss procedure in which a thin tube, implanted in the stomach, ejects food from the body before all the calories can be absorbed.

I’ve been eating a high-fat, carb-restricted diet for almost 20 years, since I started as an experiment when investigating nutrition research for the journal Science. I find it’s easy for me to maintain a healthy weight when I eat this way. But even after two decades, the sensation of being on the edge of a slippery slope is ever-present.

Many people can rattle off the names of the most popular vitamins and the foods that contain them in abundance.