Would you be willing to semi-starve in order to live longer? More to the point, would you be willing to semi-starve simply for the chance that you might live longer?
If you’re a member of the Calorie Restriction (CR) Society, the answer to that question is probably yes. Pioneered by the late Dr. Roy Walford, the CR regime (which also has several other names) seeks to extend the human lifespan. Using information garnered from animal studies, and extrapolating the results to humans, the CR Society members are attempting to redefine the natural age-limit for humans. Their primary method for this life extension attempt is to restrict their calorie intake by amounts ranging from a relatively modest 10% to a whopping 65% from a full-fed diet.
As important as the calorie restriction, though, is the nutritional aspect. Advocates of CR are quick to point out that a nutritionally poor diet is likely to shorten life, not extend it. This gives them the sometimes challenging job of trying to fit a full range of nutrients and vitamins into their restricted calorie supply. In the mildly restricted diets, this high nutrition can look like nothing more than a light version of a normal health-conscious diet. In the more highly restrictive regimes this need to cram in as much nutrition as possible becomes more obvious, leading to tightly planned eating where every bite of every day has to carry its dietary weight. In some cases, practitioners may literally eat the same highly nutritious meal every day (or multiple times a day) for years at a time.
So what started all of this voluntary restriction? CR Society members point to a body of research starting with mice, and since extended to rats, dogs, cows, and a number of other animals showing that animals with restricted diets lived longer, healthier lives than those who were free-fed. Not just longer average lives, but truly extended lives, with up to a 40% longer maximum lifespan than the control animals. Studies on rhesus monkeys, though not yet complete, indicate that CR works to extend their lives as well, though less dramatically than for rodents - about 10-20% over the controls. For obvious reasons, these results have not been proven on humans. We cannot expect study results of the effects of CR on humans for many years. Nor are the results on animals universal enough to lead to great confidence in much of the medical community. Under some circumstances, such as late-life or overly rapid introduction of the regime, CR reduces lifespan rather than increasing it. Some of these factors are reasonably well understood, others may not be, meaning that those following a CR diet might be undergoing all this dietary restriction to their detriment.
The next obvious question – what are the results so far? While it’s far too early to tell results on ultimate longevity, the CR members report a number of promising results. A rarity in increasingly heavy America, the CR members are generally thin to very thin, becoming that way slowly over the couple of years it usually takes to fully implement the diet. Their blood chemistry generally improves, with lower total cholesterol, better HDL/LDL ratios, and fewer fluctuations in blood sugar. They also report fewer minor illnesses-- an unexpected result, since the animal studies generally show a lowering of the immune system.
So what’s the downside? Aside from the uncertainty surrounding its ultimate results the biggest obstacle for most Americans is the loss of spontaneity in eating. Many Americans view diets as something done for a short period of time, usually to lose weight. The idea of restricting food intake for life is not particularly attractive. Yet for most CR practitioners, this aspect seems not to be a problem. They report that food tastes better, so that they enjoy food more, even while eating less of it. The weight loss that results from CR can be a problem for some, particularly men. There is also some concern that the very low body-weight may be a problem in and of itself. Chronic cold sensitivity is often reported, presumably due to low body fat. A CR practitioner who contracts a chronic disease may not have the reserves to cope with the heavy demands on their body’s resources. For similar reasons, CR is likely not suitable for growing children, pregnant women, or people whose lives involve heavy exercise. The diet simply doesn’t provide enough caloric energy to sustain the necessary output.
Besides the physical effects, several psychological effects have been hypothesized – including a lowered libido, and a possible increase in obsessive behavior. However, as there are currently no studies on the psychology of CR practitioners, these effects all remain either speculative or anecdotal. There is at least one proposed psychological study of CR practitioners, but as the study hypothesizes a connection between CR, obsessive/compulsive behavior, and eating disorders, the CR community has been understandably suspicious of researcher bias. At least some in the nutrition field seem to regard CR as little more than anorexia with medical sweetening to make it more acceptable.
While the practice of CR is still very controversial, the level of hostility towards its practice seems quite odd. There are hundreds of diets on the market in America, many of them vastly unhealthy, and most intended for no more worthy goal than the loss of a few pounds. CR remains unproven thus far, but ultimately the only way to definitively prove or disprove its effects is to do exactly what the CR Society is currently doing – to give it a try.