Eating Less May Extend Your Lifespan -- But Is it Worth It?
The idea that eating less can prolong life has been gaining traction in recent years, thanks to studies on many organisms, including mice, spiders, dogs and worms, that correlate fewer calories with longer life.
A group called the Calorie Restriction Society has formed to encourage and assist people in reducing their long-term caloric intake for the sake of health. Their diet, called Calorie Restriction with Optimal Nutrition (CRON), is intended to drastically reduce caloric intake without starving the body. CRONies, as they call themselves, claim that in addition to the possibility of living longer and retarding the effects of aging, they experience increased energy and mental clarity.
We're talking about more than skipping dessert. The CRON diet aims for a weight of 10-25 percent less than what you weighed in college (assuming you were healthy, not anorexic or obese). I'm 6' 2'' and weighed 160 pounds when I was 20. So if I were a CRONie, I'd aim to weigh about 130 pounds -- 55 pounds less than my current weight.
That may sound extreme, but CRONies received a recent boost from the results of a long-term study on rhesus monkeys.
The monkeys were divided into two groups, one of which was fed 30 percent fewer calories than the other. The researchers, led by Ricki J. Colman and Richard Weindruch at the University of Wisconsin, reported in Science magazine's July 9 issue that after 20 years, the dieting monkeys show significantly less diabetes, cancer, and heart and brain disease than the control group.
Calorie restriction entered the mainstream in the 1980s, when UCLA researcher Dr. Roy Walford began publishing books, including The 120-Year Diet, based on his research with mice. Walford died at 79 of Lou Gehrig's disease, and his daughter Lisa Walford now carries the torch. A prominent CRONie, she's 5 feet tall, weighs 80 lbs, and according to her recent book, The Longevity Diet, enjoys a daily breakfast of four walnuts, six almonds and 10 peanuts, which is eerily similar to, but somewhat less, than what I fed a five-ounce parakeet I recently babysat.
Another of Dr. Walford's disciples is Richard Weindruch, co-author of the recent monkey study. Weindruch also co-founded LifeGen Technologies LLC, a company that "works with drug makers to quantify the effect of possible life-extending drugs." LifeGen's business plan, based on the premise that most people don't have the willpower to limit their caloric intake by 30 percent, is to identify and replicate in pill form the biochemical processes triggered by caloric restriction.
When I reached Weindruch by e-mail, he admitted that he himself doesn't follow a calorie-restricted diet, though he does eat "lots of vegetables and not much meat." His co-author, Ricki Coleman, has similarly gone on record acknowledging that she doesn't follow a low-cal diet, despite their team's conclusion that "these data demonstrate that caloric restriction slows aging in a primate species."
While the CRONies are fasting for joy, many scientists and health experts don't buy it.
Most of the monkeys are still alive, and are expected to keep living for years, so it's too early to tell if the dieting monkeys really will live longer. And at this point, according to the researchers, the difference between the two groups in terms of the deaths that have occurred so far is not statistically significant.
But if there's yet to be a significant difference in mortality between the two groups, why has this study made headlines around the world?
Researchers employed some statistical fancy footwork to exclude monkey deaths deemed not due to age -- including deaths occurring under anesthesia while blood samples were taken. Thus the researches were able to show a statistically significant difference between the two groups of surviving moneys. Skeptics argue the low-cal diet could have made the monkeys more susceptible to health threats not usually associated with age.
Infection, for example, isn't considered an age-related disease, but caloric restriction has been shown to disrupt the immune system and increase susceptibility to some types of infection, like listeria, in fruit flies. And the effects of undereating on a number of other health indicators, like bone density and fertility, while perhaps not life-threatening, are nonetheless negative.
There's also reason to believe that laboratory conditions don't adequately simulate real life. Studies that show mice to live as much as 40 percent longer on a calorie restriction diet are done with lab mice, which have been bred for high fertility and other characteristics. According to professor João Pedro de Magalhães at the Integrative Genomics of Ageing Group at the University of Liverpool, mice derived from wild populations don't live longer under calorie restriction.
In the recent monkey study, the baseline or so-called "normal" caloric intake of the non-dieting monkeys was determined by observing how much the monkeys ate in captivity with unlimited access to food. It's possible these monkeys were overeating, out of boredom perhaps, or, like many Americans, simply because they could. If the monkeys on the "normal" diet were in fact overeating, then it's hardly surprising that the monkeys eating the 30 percent-off diet have lower rates of diabetes, heart disease, etc.
Given that the average American consumes more than 3,700 calories per day (according to the UN Food and Agriculture Organization), and that much of it comes from junk food, some calorie restriction would probably be a good thing for many of us. But if you're not fat, does it make sense to starve yourself from thin to bony?
Another question relates to the monkey chow. The materials and methods section of the monkey study doesn't identify the monkey diet, specifying only that "animals in this study are fed a semipurified, nutritionally fortified, low fat diet containing 15 percent protein and 10 percent fat."
Not all calories, protein and fat are equal. Meat from grass-fed beef, for example, has a healthier balance of omega-3 and omega-6 fatty acids. Protein from soy has been linked to man-boobs, intestinal problems in kids, and thyroid illness in adults. Trans fat increases the risk of heart disease. If the monkeys were fed a diet from McDonald's, for example, a 30 percent reduction in calories would certainly explain the relative lack of diabetes and heart disease.
So while the monkey study results are interesting, I'm sticking with my filling diet of naturally produced and minimally processed foods. And if I'm wrong? Well, if living 120 years means 120 years of semi-starvation, I'm not sure I see the point. And I would not be a pretty sight at 130 pounds.