Healthy Weight, Healthy Mind: How Important Is Exercise for Weight Loss?

We are pleased to bring you this regular column by Dr. David Creel, a licensed psychologist, certified clinical exercise physiologist and registered dietitian. He is also credentialed as a certified diabetes educator and the author of A Size That Fits: Lose Weight and Keep it off, One Thought at a Time (NorLightsPress, 2017). See all of David Creel’s articles here.

Here’s a story I’ve heard many times.

I hired a trainer I saw once a week for two months. I endured grueling workouts and was pretty faithful about working out on my own several times per week. I felt great, my endurance improved, and I could hold a plank for two minutes. But I only lost two pounds. Six-hundred dollars for two pounds! It doesn’t seem fair, nor does it make sense.

I agree this doesn’t seem fair. After all, when we work hard we want results. However, if we think about it logically, the results do make sense. Compared to making dietary changes, the short-term weight loss we experience from moderate exercise is modest at best.

Shantell is a good example. She reluctantly told me she drank approximately 12 regular sodas per day. Not counting french fries, she hadn’t consumed a vegetable in weeks. She and her kids ate fast food almost every day, and the meals she prepared at home included bologna sandwiches, hot dogs, or fish sticks. She would round out her meals with macaroni and cheese, potato chips, or tortilla chips. Although she didn’t eat a large volume of food, her diet needed a major overhaul.

Instead of trying to change everything at once, we focused on simply decreasing her soda consumption.

To my amazement, after our meeting she totally stopped drinking the ten-teaspoons-of-sugar-per-can stuff. When she returned a month later, she had lost 16 pounds. She didn’t make other changes in her eating, just the soda. If we assume Shantell consumed the same number of calories she was burning at the time we first met (her weight was stable), any calorie reduction would lead to weight loss. Table 2 illustrates how decreasing her consumption of soda (a total of 1800 calories per day) could lead to almost 16 pounds of weight loss in a month. Remember, burning 3500 calories more than we absorb equates to one pound of weight loss. So the math makes sense. Although Shantell’s diet still needed a lot of work, she was able to lose significant weight with only one change in her diet.

Now let’s look at how much exercise Shantell would need to do in order to lose a similar amount of weight. She weighed about 350 pounds, so walking burned more calories for her than for someone who weighed less and walked at the same speed. Think of it this way: The more someone weighs, the more work they do when moving that weight a given distance. For example, walking a mile with a 40-pound backpack requires more calories than walking a mile without it. In addition, because of her excess weight, Shantell’s resting metabolism was higher than an average-weight woman. I estimated she burned about two calories per minute simply sitting still. Table 3 shows Shantell would burn approximately 140 net calories per mile and would need to walk about 13 miles per day to burn the same number of calories she saved by not drinking 12 cans of soda. At two miles per hour, that would be almost 6½ hours of walking each day!

If you don’t drink 12 sodas per day, this example may seem a little extreme. But even if your extra 500 calories come from late night grazing, you’ll find it hard to “undo” those dietary indiscretions with physical activity. The point of these math gymnastics is to demonstrate that burning calories through exercise is generally more difficult than saving calories by eating differently.

This is especially true for people who can only exercise at low intensity. An elite runner can burn a lot of calories during an hour of exercise, whereas someone taking a slow walk burns far fewer calories. The runner may cover ten miles during that hour, while the overweight person walks two miles an hour. Many studies back up this principle of diet-versus-exercise for weight loss. We know that, in the short run, exercise doesn’t directly cause much weight loss. When we look at the long run, it’s an entirely different story.

In order to understand long-term weight loss success, researchers study people who are good at it. Many studies show that people who lose weight and keep it off are

physically active. Data from the National Weight Control Registry and many studies conducted by Dr. John Jakicic at the University of Pittsburgh tell us that exercise is a crucial component in keeping lost weight from reappearing. Although studies vary on exactly how much exercise is necessary to keep weight off, most experts agree that engaging in 250 to 300 minutes of exercise each week will greatly increase your chances for success.

You may wonder why short-term weight loss from exercise tends to be modest, yet exercise is almost a requirement if you want to prevent weight regain. Researchers have not yet conclusively demonstrated why exercise is related to long-term success in weight loss. Although exercise, especially resistance training, may help prevent muscle loss and a lowering of metabolic rate that accompanies weight loss, not all studies support this idea. But when we look at the many other benefits of physical activity, we can draw logical conclusions about the long-term benefits of exercise.

• The longer we stick with an exercise routine, the more fit we become. As we become more fit we’re able to increase our exercise intensity for longer periods of time. The more we can do, the more calories we burn. When we’re feeling fit we gravitate toward physically challenging things that burn more calories.
• Exercise improves mood. If we feel less depressed and anxious we’re less likely to eat emotionally or be distracted from personal health goals.
• While exercising, we are not sitting in front of the TV. If we aren’t sitting in front of the TV, we can’t be eating in front of the TV.
• If we invest in our bodies by taking time to do good things for them, we probably don’t want to abuse the body with unhealthy eating. That would be like intentionally driving through the mud after a car wash.
• For those who enjoy physical competitions with themselves or others, eating is fuel for those endeavors. If high octane (healthy food) is available, we use it.
• Feeling accomplished about physical activity can improve confidence in other areas, including wise choices in what and how much we eat.

Come back each week for more healthy weight loss advice from Dr. David Creel.