"Exercise Won't Make You Lose Weight," Or So Magazine Says

How to eat and still make your fitness goals.

Sheri Colberg-Ochs By Sheri Colberg-Ochs, PhD

How many of you saw the Time magazine cover story from the August 17, 2009 issue titled "The Myth about Exercise"? If you did see the cover, it probably immediately caught your interest as it showed a reasonably fit and young woman walking or running on a treadmill, but thinking about a cupcake with green icing and colorful sprinkles. The cover's subtitle boldly says, "Of course it's good for you, but it won't make you lose weight. Why it's what you eat that really counts." On the page where the story appears in the magazine, the headline is "Why Exercise Won't Make You Thin" with the subtitle that ends with "…[physical activity] doesn't always melt pounds—in fact, it can add them."

Why do headlines like that grab people's attention? Because they're so unexpected. Haven't you "known" for years that you have to exercise if you want to lose weight or stay thin? Every major weight loss program, including Weight Watchers and Jenny Craig, includes an exercise program. Could everyone (including you) really have been wrong about exercise and weight loss? It makes you definitely want to buy the magazine and read the article—which was really the whole point of it, not to present an unbiased or unslanted assessment of the facts.

The best rebuttal of this article (and it definitely needs one) was actually printed in a later issue of Time in August and quoted the president of the American College of Sports Medicine (ACSM), James Pivarnik. By way of background, the ACSM issued updated exercise guidelines for all Americans in collaboration with the American Heart Association back in 2007 and is very active in promoting the "Exercise Is Medicine" campaign you might have heard about. Dr. Pivarnik wrote: "I must take issue with some of the points portrayed as fact. Numerous studies have shown that exercise is indeed central to an effective weight-loss program. The key concept is a simple equation of energy balance: calories expended throughout the day must exceed calories consumed as food. And contrary to the data selected for your article, studies have shown that most exercisers are not uncontrollably hungry after a workout. We strongly encourage reporting that portrays both sides of an issue so readers can decide for themselves--instead of being led down a potentially harmful path." Bravo, Dr. Pivarnik! Well said.

This article is full of inconsistencies, misinterpretations of the studies it quotes, and inaccuracies. I wholeheartedly agree that you can easily overeat and overbalance the calories you expend during exercise if you pay no attention to your diet at all. However, no studies show that exercise causes an exaggerated or uncontrollable appetite that will send you foraging for the closest Dunkin Donuts. For individuals with type 2 diabetes, it's not an overwhelming sense of hunger driving them; rather, they may simply feel entitled to eat whatever they want to since they worked out and therefore make less appropriate food choices. But, you still have to control your food intake to manage your diabetes effectively. You should never reward your workouts with a sugar-covered cupcake. Keep in mind that you usually expend 300-600 calories per hour of aerobic work, and it's easy to consume all of the calories back, given the wide variety of high-calories foods you can order or buy just about everywhere. You can eat more calories than you expend in an hour of exercise in a peanut butter sandwich or a small order of French fries—or a cupcake.

While you can still eat after you exercise, please do not abandon your healthy diet altogether! Moderation in all things is still a key to controlling diabetes and your body weight. I do agree with the part of the article that talks about how you can potentially expend more energy moving more all day than just during your gym workout. Spend the rest of your day wisely, taking extra steps and doing more spontaneous physical movement to help keep your weight under control. For type 1s, you will likely have to cut back on your insulin if you don't want to chase post-exercise low blood sugars all the time, and you should probably make sure you eat some carbs and protein after exercise to prevent later-onset lows. A cupcake would never be the best choice of a post-training snack in any case. If you cut your insulin back during and/or after exercise, you can get by with eating minimal extra food to prevent hypoglycemia. Chasing lows with lots of extra calories can actually cause weight gain, but that's not what the article was really referring to since it did not focus on diabetes. Choose to treat a low with fewer calories by treating it with straight glucose (e.g., tablets, gels, and liquids) rather than something like juice or sugary treats—it's actually more rapid and less caloric. The last thing you want to do is negate the calories you just worked off by treating low blood sugar, especially if weight loss or weight maintenance is your goal.

The research actually does show that you can lose weight through exercise alone, but it may take more like an hour a day as well as monitoring your food intake, and it's hard to lose weight quickly when you're gaining muscle. Muscle mass is more dense than fat (meaning that it weighs more), but gaining muscle benefits your overall metabolism and eventually increases your daily caloric needs somewhat. Plus, more muscle means you have can store more carbs as glycogen, which will help you with your blood sugar control. My advice is to stop watching the bathroom scale so much and focus more on how your clothes are fitting—doing so is a much better reflection of your body fat levels than your body weight.

As for losing weight through dieting alone, I would strongly advise against it—even though the article in Time makes it sound like you should avoid exercise if you want to get thinner. Actually, without exercise, you will likely lose a lot of muscle mass and not just fat, which leaves you with less muscle and a lower metabolic rate when you're done. If you regain the weight (like 90-95% of people eventually do), then you will end up with a higher percent of body fat than if you never lost any weight in the first place—and likely higher blood sugar levels when you eat carbs.

So, what should you do if you want to lose weight? Consider weight loss a multifaceted approach that includes making better dietary choices and exercising moderately. Pick healthier foods with a lower calorie density—such as an apple instead of an apple-filled muffin—and if you do reward yourself for working out with food, check the calorie content first to make sure you don't eat more calories afterwards than you actually expended! You should also focus on simply moving more throughout the day (including standing up more often and longer), not just doing your gym workouts, for the best results. But, whatever you do, don't avoid exercising for fear that it will make you gain weight! (If you still believe that after reading this column, we need to talk….)

For more information on all of the benefits of physical activity, please consult my new book, The 7 Step Diabetes Fitness Plan: Living Well and Being Fit with Diabetes, No Matter Your Weight. Check my Web site (www.shericolberg.com) for more details or to order a copy today.

Read Sheri's bio here.

Read more of Sheri Colberg-Och's columns.

NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.


Last Modified Date: June 17, 2013

All content on dLife.com is created and reviewed in compliance with our editorial policy.

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