No, but it will seem longer.
That’s my attempt at a joke. But maybe it’s not a joke. Maybe it’s true.
For many years there’s been an idea—derived initially from animal research—that restricting caloric intake makes a person live longer. Here’s a report on the latest findings, which are based in part on a study with a pretty Draconian design for its subjects. I certainly hope they were well-compensated for this kind of suffering:
Pennington is one of the few places in the world with these hotel-room-sized microenvironments, the most rigorous way to measure how many calories a person burns and where they come from””fat, protein, or carbohydrates.
After a night of fasting, participants entered the calorimeter promptly at 8:00am, and until 8:00am the following day they weren’t allowed to leave or exercise. Researchers delivered meals through a small, air-locked cupboard. As fresh air circulated into the room, the air flowing out went through a series of analyzers to measure the ratio of carbon dioxide to oxygen. Nitrogen measurements from urine samples help calculate a total picture of each participant’s resting metabolism.
Sounds like fun, doesn’t it? The findings were as follows:
…[C]utting calories, even modestly, lowered people’s metabolism by 10 percent. Some of that could be attributed to weight loss (on average folks lost 20 pounds over two years). But according to the study’s authors, the majority of the change had more to do with altered biological processes, which they observed through other biomarkers like insulin and thyroid hormones…“After two years, the lower rate of metabolism and level of calorie restriction was linked to a reduction in oxidative damage to cells and tissues.”
On reading that, one of the things I noticed is that it may validate the observation many dieters (and would-be dieters) make that dieting lowers one’s metabolism. This makes it more difficult to lose weight, not easier, because the same amount of food is used more efficiently by the body, although of course if the calorie restriction is big enough weight will be lost nevertheless. But a calorie restriction of 25% (that’s what was done in the study, amounting to 500 to 800 calories less per day), strictly held to over two years and resulting in a 10 pound per year weight loss, is just another indication of how difficult it is for many people to lose a very significant amount of weight. One would think the loss would be more, if you go by the old idea that 3500 calories of reduction leads to a pound of weight loss. By those calculations, the subjects should have lost far far more weight than they did.
But was the diet worth it in terms of health advantages? Do reduced metabolism and “a reduction in oxidative damage cells and tissues” make up for the deprivation? The study wasn’t long enough to determine the answer. Researchers differ:
Fontana’s own work with Calerie trial data suggests changes to specific insulin pathways matter more than overall metabolism decrease. He also points to studies where rats were made to swim in cold water for hours a day, dropping their metabolism. They didn’t live any longer than room temperature rats. In other studies, scientists overexpressed enzymes that protected mice from free radicals. They didn’t live any longer either. Redman’s data is interesting, he says, but it’s not the whole picture. “Twenty years ago the dogma was the more calorie restriction the better,” he says. “What we are finding now is that it’s not the number that matters. Genetics, the composition of the diet, when you eat, what’s in your microbiome, this all influences the impact of calorie restriction.”
That’s certainly been my personal experience, which of course is merely anecdotal.
To my surprise, that joke I made at the beginning of this post was echoed at the end of the article about the research:
Jeffrey Peipert [is a] 58-year-old ob-gyn [who] participated in the Washington University trial nine years ago, hoping to bring down his weight, which he’d struggled with his whole life. When he went in, his blood pressure was 132 over 84; after a few months on a restricted calorie regimen it dropped to 115 over 65. A year in he lost 30 pounds. But six months later he quit. It was just too much work. “It took away my energy, my strength, it definitely took away my sex drive,” says Peipert. “And tracking calories every day was a total pain in the neck.”
Today he’s gained all the weight back and has to take a pill for hypertension. But at least he feels like he’s living well, even if he maybe won’t live as long.
I know that the Taubes people will come out of the woodwork and say they’ve got the answer. I would like to caution them that, while I’m glad that way of eating works so well for you (and more power to you!), that sort of approach not only does not result in weight loss for me and for many others, but there are those of us who find we feel physically bad on the diet, too.
Different diets seem to suit different people. Each person needs to find the best balance for him/herself. That’s a cliche, but it seems true. Some people with “good” health habits die young, and some with “bad” health habits live a long and happy life. The rest is statistics, but most of us don’t plot our entire lives by statistics.