Eating Less May Extend Your Lifespan -- But Is it Worth It?
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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.
Ari LeVaux writes a syndicated weekly food column.