Home / Resources / Featured Writers / Is It Really True that Exercise Won’t Make You Lose Weight?

Is It Really True that Exercise Won’t Make You Lose Weight?

Oct 29, 2009




How many of you read the Time magazine cover story from the August 17, 2009 issue titled "The Myth about Exercise"? If you did see the cover, it likely 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 the story appears, the headline reads "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 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, certainly not to present an unbiased or unslanted assessment of the facts.


The best rebuttal of this article (and it definitely needs one) was printed in a later issue of Time in August and quoted the president of the American College of Sports Medicine (ACSM), James Pivarnik. In 2007, the ACSM issued updated exercise guidelines for all Americans in collaboration with the American Heart Association and is very active in promoting the "Exercise Is Medicine" campaign in the United States and abroad. 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." Well said, Dr. Pivarnik!

The Time magazine article is full of inconsistencies, misinterpretations of the studies it quotes, and inaccuracies. I whole-heartedly 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 shop. 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 since they worked out and make less appropriate food choices. But, you still have to control food intake to manage your diabetes effectively, and you should never reward your workouts with a sugar-covered cupcake. 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 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, you cannot afford to abandon your healthy diet altogether! Moderation in all things is still a key to controlling diabetes and body weight. I also 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 1’s, 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 in people with 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.    

Research shows 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. Without regular 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….)


If you need tips for getting started on an exercise program, check out my book entitled The 7 Step Diabetes Fitness Plan. For people with any type of diabetes who are already more active, you will benefit more from Diabetic Athlete’s Handbook. For other tips on exercise, fitness, diabetes, nutrition, and more, please visit my website and exercise blog at www.shericolberg.com.

 © 2009 www.DiabetesInControl.com