Eat a lot less, live a lot longer
LAST WEEK, I wrote that the best way to live healthier longer was to eat less and exercise more. Meticulous readers asked which of these two approaches, precisely, had more scientific support. Such questions may reflect wishful thinking: Those who exercise a lot might wonder if they can eat the equivalent of steak and fries every night. And for those who don’t want too much exercise, might they focus instead on eating less?
Unfortunately for those who, like me, have modest will power at the table, the data are clear. The most robust way to increase healthy lifespan in a broad variety of organisms is in fact calorie restriction. In other words, it behooves us to cut our calorie intake markedly, while still maintaining a balanced diet that includes essential vitamins and minerals. Whether we can bring ourselves to do so is another question entirely.
In the 1930s, Clive McKay of Cornell University stumbled on a striking finding in the laboratory. Lab rats that were put on a diet that reduced their calorie intake by over 20 percent turned out to live significantly longer and healthier than other rats. Since then, many researchers have proved the same fact in yeast, worms, flies, mice, even monkeys. Similar benefits are likely in humans. Of course, true calorie restriction would require many of us to forgo the rough equivalent of breakfast every day, or to find other ways to significantly lower total calories. No more ice cream, hamburgers, fries — at the very least.
Popular culture abounds with diet fads that discourage or promote specific types of food. The low-fat diet, the low-carb diet, the high-protein diet, the all-raw-foods diet — the list goes on and on. Whatever the effect of these diets on weight loss, there’s little conclusive data on how they might affect longevity. The preponderance of scientific evidence seems to point to total calorie intake as the key factor.
Who among us, you might ask, would have the fortitude to emulate the calorie restriction studies conducted on animals? It turns out that there are at least hundreds of Americans, and many more individuals worldwide, who are severely restricting their calorie intake in the hopes of extending their healthy lifespans. Studies have indeed found that key cardiovascular measurements, such as blood pressure and heart rate, are much improved in individuals who significantly restrict their calorie intake.
At my last meeting with members of the Calorie Restriction Society of America, it came up that their immediate past president had just died. I asked them at what age, and they replied: “He was nearly 100, and healthy to his last day.”
I’ve conducted research in this area. People ask me, in discussions online or on the phone, whether I have ever tried calorie restriction myself. (Sadly, I am not asked this question in person.) After all, the data are so clear. Unfortunately, we have been strongly programmed by evolution to eat, and in these times of calorie overabundance, our survival instinct works against us improving our health.
Picture yourself on the savanna, tens of thousands of years ago. If we were ever fortunate enough to find edible grains or hunt down game, we were programmed to eat as much as we could. We did not know when our next meal would come. If we did not eat as much as humanly possible, selective pressure favored those who might have taken their fill in the same situation. Today, with a refrigerator and a supermarket nearby, I have an infinite supply of calories available anytime. Is it any wonder that my evolutionary drive overcomes my modest will power, and I eat more than I should, despite knowing it is not good for my health?
That is why, even though intellectually we all understand that eating less is a good idea, it is so hard to turn down a doughnut and vanilla latte for a snack, or french fries and ice cream at dinner. But we all should try to eat less, because science has indicated that we would live healthier longer, if we were to only consume less calories.
Christoph Westphal, a guest columnist, is a biotech entrepreneur and a partner at Longwood Founders Fund.