It turns out there is a Calorie Restriction Society dedicated to finding out if the same sorts of benefits are seen in humans. There are roughly 500 dedicated members. But the president, Brian Delaney, estimates that tens of thousands of people worldwide are participating in some capacity, and maybe 2,000-3,000 are following a rigorous form of the diet. And the program is a lot more popular with males than females. Some of the practitioners are actually participating in studies on calorie restriction, while others are just sort of serving as guinea pigs in their own experiments. Many get labs done prior to starting calorie restriction and then periodically compare their new numbers, to figure out whether various markers of health are improving.
The goal of the CRS diet is to “obtain optimal nutrition from the fewest calories.” Unlike in anorexia, the goal isn’t to look skinny. Weight loss is viewed as an undesirable byproduct of consuming 30% fewer calories than is typically recommended. Adherents are hopeful that their calorie restriction will translate into a longer lifespan: 110, 120, or even 130 years or longer. And guess what? One of the main proponents is Dr. Ray Wolford, who was one of the original Biopsherians I wrote about in my last blog post.
The weight loss is supposed to be one of the worst parts of the diet. Just to give you some idea about how skinny we’re talking about, the president of the CRS is 5’11” and his weight ranges between ~ 130-140 lbs. So pretty thin, but not beyond the pale. The constant hunger, on the other hand, appears to be something people can get used to. That’s what they say anyway!
The early research on calorie restriction in primates is kind of mixed. A study on rhesus monkeys published in Nature found that calorie restricted animals don’t live longer. So that’s sort of a bummer. But there was a lot of encouraging health data! The diet improved cholesterol and oxidative stress levels in males but not in females. And it reduced the incidence of cancer, which is good.
Human studies are also pretty ambiguous. Calorie restriction results in heart function that resembles that of people decades younger. And testosterone levels in calorie restricted-males are lower than those associated with a typical diet (it’s hypothesized that calorie restriction tips the balance in favor of longevity vs reproduction). Some natural experiments also suggest that calorie restriction prevents cancer. Norwegian women who were adolescents when World War 2 limited the amount of food available have a reduced incidence of breast cancer, and so do women who struggle with anorexia early in life. But it appears that calorie restriction can’t be too severe, or it may actually predispose individuals to cancer later in life; Israeli Holocaust survivors subjected to starvation had higher rates of breast cancer, as did Dutch women who lived through the Hunger Winter. And calorie restriction may cause problems with maintaining bone density, so that has to be added to the con side.
A calorie restricted diet probably isn’t in the cards for me. I love food too much! But it does seem like, on balance, reducing calorie consumption is a good idea for most of us. And sort of extreme calorie restriction, like that advocated by the CRS, might not be a bad idea. The whole idea of the CRS is kind of intriguing to me.