Responding to Readers’ Questions on Weight Loss

The following originally appeared on The Upshot (copyright 2015, The New York Times Company). It was written as a follow-up to this post.

In an article on Monday, I discussed the evidence showing that diet is much more important than exercise when it comes to losing weight. You had many thoughtful comments and questions — so many that we thought it might be useful to respond to some of them here.

Many of you argued that exercise worked for you, so how could my arguments be true?

Every time I write on nutrition, I try to emphasize that diet is a very individualized thing. In my recommendations for healthy eating in April, I stressed that what might work for you might not work for someone else. I am thrilled that many of you have found an exercise and nutrition regimen that keeps you healthy. But there’s no evidence that your plan will necessarily work for anyone else, and my focus is on what the collected evidence and data tell us.

Some readers were upset that I said exercising seven days a week for 30 minutes is unsustainable.

Again, I’m not saying that you can’t do it. I’m saying that the collected research (and there is quite a bit) says that most people cannot sustain this level of activity. It’s not just a matter of willpower. Some people can’t find the time, or have other priorities, or just can’t do it for physical reasons.

Earlier this year, I committed to six days of vigorous exercise for 30 minutes a day using the P90X3 system. I missed very few days. But when my three months were up, I cut back to four to five days. I think that’s best for me; I can’t tell you what’s best for you.

Speaking of me, many of you seemed to think I was ignoring the many other benefits of exercise, or that I was trying to argue that people should be sedentary.

In emphasizing the health benefits of exercise, I said, “I can’t say this enough.” And evidently I can’t say this enough. I’ll try again: There aremany benefits to exercise above that of weight loss. That’s why I exercise. That’s why you should be active, too. But you shouldn’t believe that it is more important than what you eat — or even as important — when it comes to achieving a healthy weight.

Some readers argued that exercise helped suppress their appetite, or that there were no “obese marathon runners,” or that building more muscle leads to weight loss.

First of all, I think we can agree that people who compete in marathons aren’t typical. Moreover, I know plenty of people who do run quite a bit and still struggle with their weight. As for exercise suppressing appetite or leading to increased fat burning, these are the arguments many have used for years, and unfortunately studies show they don’t lead to the changes people hope for.

Some readers said I was buying the argument that a calorie is a calorie; they thought the work of many, like Gary Taubes and Nina Teicholz, showed that wasn’t true. (They may be right, but I think the jury is still out.) And some readers thought I was saying that all overweight people were overeating.

In my writing, I’ve tried not to leave the impression that all dieting is simply a matter of eating less, and I want to reiterate that point if I wasn’t clear enough on Monday. Healthy eating isn’t just about amounts. As Idiscussed in this video, there is good evidence that all diets work, to some extent, and that almost all people on diets eat less than they did before. But those results are often unsustainable. That’s why I made the case on Monday that more gradual and sustainable change in eating behavior is more likely to achieve success than restrictive diets.

I stand by what the evidence shows. What you eat is more important to achieving a healthy weight than how much you exercise. If your goal is to lose weight, then you are more likely to get better results in the kitchen than in the gym. This should not in any way be taken to mean that there is no benefit from being physically active. There are many, many good things highly associated with exercise, and all of them matter. Weight control, unfortunately, just doesn’t seem to be one of them.


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