Vice President of Research & Development at Nutrisystem
On the surface, the role of exercise in a weight loss program seems clear: exercise burns calories, which helps you lose more weight. It’s true that physical activity – whether we’re talking about walking from one side of a room to the other or working up a serious sweat at the gym – adds to the number of calories your body burns. But how much weight can you lose by exercising?
I guess the best way to answer that question is “it depends on how much physical activity you’re willing to do.” Consider that an overweight person, on average, will burn about 100 calories by walking 1 mile. (That person will also burn about 100 calories by jogging a mile – they’ll just get there faster.) Also consider that a pound of fat is worth about 3500 calories. So to lose a pound, just by walking, you’d have to walk about 5 miles a day every day for a week. A study that looked at the effects of exercise – without reducing food intake – on weight loss found that people who were given a high-intensity exercise prescription (equivalent to jogging 20 miles per week) lost about 8 lb over 8 months. Certainly, an 8 lb weight loss is nice, but it may not feel like enough reward for the effort of jogging 20 miles per week for 8 months! Some studies even suggest that a weight loss program of diet and exercise results in the same amount of weight loss as a program of diet alone.
This is not to say that you shouldn’t exercise as part of your weight loss program. You certainly should! Besides burning calories, physical activity has a number of well-established health benefits. Even if you don’t lose an ounce from exercising, here’s a sampling of aspects of your health that improve with exercise:
- – Cardiorespiratory fitness
- – Insulin sensitivity
- – Mood
- – Bone health
- – Blood pressure
- – Memory/Concentration
- – Body composition
- – HDL (“good”) cholesterol
- – Quality of Life
Body composition is an interesting one. When you lose weight, most of what you lose is fat or (especially in the beginning) water. But you also lose fat-free mass, which includes muscle. When you exercise during weight loss, the ratio of fat to fat-free mass that you lose is greater. In other words, being physically active helps you lose more of what you want to lose and keep more of what you want to keep.
When it comes to weight loss, though, probably the clearest benefit of exercise is in helping you keep weight off. There’s a database called the National Weight Control Registry (NWCR), which contains a lot of valuable information about people who are successful not only in losing weight, but also in maintaining that weight loss. Everyone in the registry has lost at least 30 lb and kept it off for at least 1 year. One thing that stands out about NWCR members is that they tend to do a great deal of physical activity. Some are very serious about working out and spend several hours per week doing vigorous exercise. But, by far, the most common activity that NWCR members report is… (drum roll please)
So if you haven’t already, get moving. But keep your expectations in check. Don’t expect to see your weight loss speed up when you exercise. The contribution to your weight loss might be too small to notice. And you probably won’t feel improvements in insulin sensitivity, body composition, good cholesterol, and the like. That doesn’t mean that your health isn’t improving behind the scenes. You’ll also be building a habit that will help you maintain your weight loss success over the long term.