Reducing Calories Improves Immunity

The two-year results from the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) clinical trial—the first controlled study of calorie restriction in healthy humans—were released last week. The purpose of the study was to determine the benefits and hazards of calorie restriction. Animal studies have demonstrated that reducing calories up to 40% allows the animals to live longer, but at a cost: their immune systems become compromised and as a result they have more infections. On top of that, you can restrict that many calories from animals because you feed them, but it’s unrealistic in free-living humans.

After meticulously assessing each person’s basal caloric need, they asked half of the 200 subjects to restrict their calories by 14% and sustain it; if they required 2,100 calories per day, that’s a reduction of about 300 calories a day. That’s just two tablespoons of oil per day; skip the mayo on a burger and get a small order of fries instead of a medium, and that’s it. There are hundreds of little changes like that a person could make to reduce calories by 300 a day.

Under-eating just that little bit and maintaining it triggered an interesting effect: it stimulated the immune response to operate even better than before. I’ll talk about why (and a confirmation of what I’ve always said) on Saturday.

What are you prepared to do today?