A few days ago, I saw the pharmacist at my local CVS and remarked on how thin he had become. “I have been doing marathons," he told me, "and I am planning to do a 100 miler next week.” Never overweight, his seemingly excessive running seemed to have removed every ounce of fat on his body. Exercise also affected the shape of my pudgy dachshund, whose body resembles a hamburger bun more than a hot dog roll. A house guest brought her very young, thin dachshund with her and the two dogs seemed to be in constant motion until they went to sleep at night. By the time my human and dog guests left, my dog felt noticeably lighter when I picked her up.
No one disputes the relationship between physical activity and its effect on "burning up" calories. Indeed the opposite situation—how a sedentary lifestyle causes excess weight—is well recognized. But how much exercise should we be doing? It is unlikely that most of us will take up long-distance running or spend hours in a dog park playing catch with our pup to drop several pounds, although both activities will surely help our weight loss efforts.
My scan of website pronouncements about exercise duration and weight loss resulted in confusion and uncertainty. Depending on the year, the website, and the authority (governmental, medical, or self-imposed) the amount of time one should be exercising fluctuated more than the stock market. A Mayo Clinic article recommended 30 minutes a day to prevent weight gain, and more to lose weight. The chart showing how many calories a 160-pound man would use engaging in different types of physical activity for an hour was useful, if one were choosing an activity based on calories burned. For example, playing golf (and presumably walking and carrying one’s clubs) used up 314 calories, but water aerobics used 402.
Another website, VeryWell Fit, quotes the American College of Sports Medicine's recommendations of 150 to 200 minutes a week of moderate-to-high intensity exercise; aerobic dancing, jumping rope, hiking with a heavy backpack, or running. Engaging in hours of vigorous exercise would make sense if the person were already extremely fit, like my pharmacist. But what about those individuals whose lifestyle is best described as sedentary, who might even be courting injury if they engaged in a vigorous exercise program without supervision?
Might research studies on the amount and intensity of exercise help to provide an answer?
A year-long study monitoring weight loss of sedentary women did not provide compelling evidence for choosing vigorous over moderate exercise for weight loss or longer duration over shorter duration among women following a calorie-reduced diet. In another study of sedentary overweight women who were following a reduced-calorie diet, the effect of exercise intensity and duration was also measured for a year. Here too, the duration/intensity of the exercise did not affect weight loss, except for women who exercised less than 150 minutes a week. They lost fewer pounds than women who exercised longer.
But is exercise even necessary for weight loss? Many weight-loss experts claim that exercise is unnecessary in a weight loss program. They point out, as in a 2017 blog originally on Vox, that exercise does not burn off enough calories to make a difference unless a controlled calorie food plan is also followed. This is no surprise. Playing golf does not use up enough calories to compensate for an after-golfing lunch of a cheeseburger, French fries, and a beer. No matter how much running around my dachshund does, she will not lose weight if I submit to her begging for cheese. In the studies in which weight loss with exercise occurs, the subjects are told to follow a diet plan; they are not allowed to reward themselves with two jelly doughnuts after an early morning boot camp workout class.
Exercise’s benefits on our general health and mental well-being are well known to those who exercise regularly. When exercise becomes impossible because of injury, weather, time, work, or family obligations, its absence is often perceived as feeling sluggish, perhaps not sleeping well, and experiencing more stress. But these benefits are irrelevant to those who don’t exercise. It takes a lot of work to convince someone sedentary that he or she will be more physically and mentally energetic with regular physical activity. Preaching this sermon to non-believers usually has little effect.
Perhaps the answer as to whether exercise is necessary to prevent weight gain and/or to support weight loss should be left to the individual. We give so much advice about exercise that it is possible the listener no longer hears it. Let the individual decide whether or not to engage in regular physical activity and if so, how much.
Sometimes people will find themselves doing more physical activity than planned because they are sight-seeing in a new city and walking much more than usual. How often have we heard the statement, “I ate all I wanted on my trip, but we walked so much I lost weight!” Or someone may move from a suburban area to an urban environment and find that driving a few blocks takes longer than walking, or that finding a parking space takes longer than getting to the destination on foot.
Exercise may increase because the individual joins a meet-up group that goes on local walks or finds himself walking to a dog park with his dog every day. A neighbor signed up to give tours of a nearby historic park and was walking four or five miles a day, albeit slowly. Another gave tours of a local museum. Neither perceived themselves as exercising, but both told me they had lost a few pounds as a result.
If or when this increased physical activity promotes weight loss, an individual may decide to keep it up and indeed increase it or engage in additional forms of physical activity such as a recreational sport or going to a gym. If the decision to do so is based on personal experience rather than advice or instructions from weight loss consultants, continuing the exercise has a better chance of becoming part of a new, healthier lifestyle.