How Healthy Are Members of the Calorie Restriction Society?

In my last video on caloric restriction and longevity, I talked about the four primate studies done to date. What about dietary restriction studies in humans? Life-long randomized controlled trials are not going to happen, but there have been shorter-term trials, studies of those who voluntarily calorically restrict, as well as a variety of creative approaches to answer the question: Does eating less help you live more? For example, do those suffering from anorexia live longer? Far from it. Anorexia nervosa is one of the deadliest mental disorders. People with anorexia die at a rate about 10 times that of the general population, suffering from a range of electrolyte abnormalities, anemia, osteoporotic bone fractures, and cardiac arrhythmias. Developing chronic anorexia from age 15 would be expected to shave 25 years off a woman’s lifespan.

Anorexia is an example of extreme caloric restriction. As many as nearly a third diagnosed with the disease seeking treatment have a BMI under 15, about half the weight of the average American woman. Unlike laboratory protocols that dictate caloric restriction without malnutrition, those with anorexia can suffer from starvation-related nutrient deficiencies so severe they can go blind. Their contracted lives may, therefore, not bear direct relevance to the question at hand, not to mention that one in five anorexia victims die by suicide.

The only long-term human study of extreme caloric restriction was the infamous Minnesota Starvation Experiment that used conscientious objectors as human guinea pigs during World War II. Again, unlike caloric restriction experiments designed to meet recommended daily allowances of essential nutrients, the Minnesota Starvation Experiment was deficient on purpose. The malnourished study subjects suffered from chronic weakness, painful leg swelling, and severe emotional distress. Interestingly, though, half of the study subjects went on to make it to age 80, living at least eight years longer than expected for men in their generation, though other factors peculiar to a pacifist cohort could certainly have played a role.

Speaking of unusual groups, self-styled CRONies (for calorie restriction with optimal nutrition) are active members of the Calorie Restriction Society, started by caloric restriction researcher and practitioner Roy Walford. He attempted to popularize the practice in the 1980s with his book The 120 Year Diet. Sadly, Walford himself died well short of the promised 120 at age 79 (of ALS).

A study of CRONies who had been restricting their intake by about 40 percent compared to the standard American diet for an average of six years were nearly ideal weight, with a BMI of 19.6. Based on the best available studies with the longest follow-up, the optimum BMI for longevity is around 20 to 22. They also dropped their blood pressures to near ideal levels of 112 over 69 within their first year of caloric restriction. Their cholesterol, inflammation markers, blood sugar control, and less atherosclerosis were all superior to a group of age-matched controls (who were on average overweight). This may just be from weight loss, though. A year-long randomized controlled trial of caloric restriction versus exercise to lose the same amount of body fat found similar improvements in cardiovascular risk factors.

Data on mortality rates or longevity of caloric restriction practitioners are not yet available, but there are some rate-of-aging indicators that appear positive. For example, CRONies have slightly lower core body temperatures, 98oF compared to 98.3 in normal diet controls, even compared to an endurance-trained control group with similar body fat. There are laboratory animal data that support a link between lower core body temperature and longevity, and the Baltimore Longitudinal Study of Aging found that men with lower body temps lived longer. However, women tend to have slightly higher body temperature yet live longer; so, the relationship is not completely clear.

CRONies also had significantly more youthful measures of heart rate variability and left ventricular diastolic heart function, two well-accepted markers of cardiovascular aging. However, they didn’t just eat less, they ate better. The CRONies reportedly strictly avoided most sugary and processed junk. Similar improvements in cardiovascular risk factors are seen among those eating healthier (whole food plant-based) diets without conscious calorie restriction. All in all, long-term practitioners of calorie restriction appear to be in excellent health, but they’re a rather unique, self-selected bunch of individuals. As always, you don’t really know until you put it to the test. Enter CALERIE, which stands for Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy, the first large long-term clinical trial to test the effects of caloric restriction. Find out what it found in my video The Benefits of Calorie Restriction for Longevity.