My mom sent me an article in The New York Times about a clinical trial out of Boston that examined the notion of whether a calorie is, in fact, a calorie, as we’ve all been told pretty much since time immemorial.
The article is here:
If you’re not feeling clicky, in essence, the small trial – which the authors hope to expand in follow-ups – concluded that people on a very low-carbohydrate diet (Atkins, in this case) expended 300 calories more per day than they did when they were on a low-fat diet, and 150 more calories per day than they did when they were on a low-glycemic-index diet. These findings suggest that our bodies’ metabolisms adapt differently according to the kinds of calories that we take in. All calories are not built equally, metabolically speaking, and it’s important to understand how these processes work not only for weight loss, but also for the maintenance of weight loss. If I were a publicist for Atkins, I’d say something to the effect that following a high-protein regimen turns your body into a fat-burning furnace, or something. Fatties like me get excited, thinking that we can eat 300 more calories a day, since our body is torching them anyway … bring on the jerky! I’m barely kidding. That is definitely what some people will take away from this study.
Metabolism is worth thinking about. A chief argument for strength training is that as we build muscle, we increase our resting metabolic rate. Muscle burns calories just to exist, where fat just sits there: your body supports muscle with oxygen and nutrients, and it takes energy to do that – fat, not so much. There are a host of other reasons to strength-train, by the way; elevating your metabolic rate is but one of them.
Here’s a curve ball, though. One of my new favorite gurus, Dr. Joel Fuhrman, contends that a fast metabolism is not the secret to weight loss. In fact, a slow metabolism is a good thing – you’re not wearing your systems out as fast. Slowing down will prolong your life. Not “sit on your ass” slow down, but “work more efficiently” slow down.
He explains it much more clearly (and less snarkily) than I do:
Here’s my take on the whole thing. We’ve known for a long time that “a calorie” isn’t simply “a calorie.” The 300 or so calories in a Snickers bar aren’t the same as the 300 or so calories in a salad with chicken. So it’s not news that the type (and I would contend the quality) of calories that we take in makes a difference. The Boston study was purely interested in the relationship between what we eat and how many calories we expend, and it applied that relationship to weight loss/maintenance and pre-obesity, or a tendency toward obesity. The study didn’t look at things like the subjects’ blood pressure, cholesterol levels, triglycerides, blood sugar, or VO2 max, which is a measure of physical fitness. Because it focused on one piece of the puzzle, it didn’t look at the entire picture of health, or at the feasibility of pursuing a high-protein regimen in the long term – the duration of each diet was 1 month in the trial. So while the study is interesting and important, it doesn’t tell us much, realistically, about Lifestyle.
The study didn’t address physical activity at all, although it’s worth noting that the lead investigator said that “when the subjects were eating low-fat diets, they’d have to add an hour of moderate-intensity physical activity each day to expend as much energy as they would effortlessly on the very-low-carb diet.” I don’t like the words have to and effortlessly. Those semantics brush awfully close to a fundamental problem with the larger weight-loss battle, which is the desire to do it quickly, easily, and with no exercise.
Lest it seem that I’m bashing this entire enterprise, let me state clearly that I’m a big fan of the investigator in this trial and of his work on childhood obesity. I’m also a big fan of the author of the Times article. By its nature and definition, a clinical trial can’t look at everything. These studies are only called rigorous when they isolate something to examine, keeping the outcome measures tight. I also think that it’s important to understand the interactions of what we eat, how our body works, weight loss, and maintenance of weight loss (speaking as one who didn’t quite make it in that regard). One can also make the case that just losing some weight, regardless of how, can make a big impact on health; however, the fact remains that the isolating nature of a clinical trial disallows the big picture and the interplay of the thousands of influences, choices, actions, and processes that make up a Lifestyle.
If you go on a high-protein diet, you will lose weight. You will also get winded climbing stairs, and light-headed in a Yoga class. I know, I’ve been there. If you go on any diet and don’t move around, you’re missing the world of benefits that exercise brings: reduced risk of chronic disease; strong bones and muscles; stress relief; better sleep; improved cardiovascular function; and on, and on, and on. If you go on a high-protein diet, you’re therefore eating fewer plant-based foods, and you’re cheating your body out of the world of benefits that they bring: reduced risk of chronic disease; reduced risk of cancer; better skin; better digestion; more satisfaction and satiation after eating; longer life; and on, and on, and on.
I’m afraid that no clinical trial will be able to deliver “an answer.” I’m not even sure that longitudinal studies like The China Study or the Framingham Heart Study, which are more complicated and expensive than clinical trials, can. I also don’t think that we should wait around for “an answer.” Start today. Make good food decisions. Move around.
If you really want to super-geek-out and read the Boston study results, here you go, you geek (and I love you for it):
Today is Square One, friends. Take the time to educate yourself, and make the best decisions you can.
 It did look at hormone levels as part of energy expenditure.