The Negative Calorie Effect

Are there “negative-calorie” foods—foods that burn more calories than they provide? Some Web sites would like you to believe that celery, carrots, or beets fit that bill. But the fact is, none of these foods actually burns more calories than it provides.

And you don’t need them. Scientific studies show that there is actually something better: foods that give you the energy and nutrition you need, while helping you trim away excess weight.

Let me describe a study conducted by our research team that showed the remarkable power certain foods have. Our participants were women who had been wrestling with weight problems for years. Many reported that their metabolisms seemed very slow. One said, “When I was young I could eat anything, but nowadays I gain weight just by looking at food!”

And it’s true: for many people, metabolism does slow over time. We know that because we can measure it. Arriving at our laboratory early in the morning, we fitted each participant with a special device that sampled the air she inhaled and exhaled. With some simple calculations that told us her calorie-burning speed.

Once her metabolism was measured, each participant then ate breakfast. Immediately, her metabolism picked up. As she absorbed the nutrients from the foods she ate, her metabolism rose and stayed higher than it had been for several hours. That’s normal.

But then, each participant began a low-fat plant-based diet. No meat, no dairy, no eggs, and keeping oils to a minimum. Fourteen weeks later, the participants came back to the laboratory and had their metabolisms measured again. And we found that the average after-meal metabolism was now 16 percent higher than before. That might not sound like much. But if you get that extra boost three times a day, the calorie burning adds up. In other words, a low-fat plant-based gives you a weight-control edge.

You can think of this as a “negative-calorie effect.” It does not mean that foods have no calories, or less than zero calories. Rather, it is a “calorie-subtracting” effect. The foods you eat have calories and healthful nutrients, and some of those calories power your body, while others are simply lost as body heat.

For extra credit, tweet photos of your favorite plant-based meals to @PCRM with #PlantBasedRx and let us know what you think.