Can you lose weight without exercising? Plenty of sweat-averse dieters out there sure hope so. And who hasn’t heard that whole “weight loss is 80 percent diet, 20 percent exercise” stat?
Experts anything but agree on the actual split, but it’s hard to ignore the fact that when it comes to losing weight – and keeping it off – diet and exercise have two totally different roles.
To lose weight, you need to burn more calories per day than you eat. Called a caloric deficit, it’s the bottom line of weight loss, and there are two ways to make it happen: Burn more calories or eat fewer calories. Exercise obviously belongs to the “burn more” camp, while dieting is all about lowering your caloric intake.
However, it’s far easier to achieve that caloric deficit through dieting compared to exercising. Think of it this way: Healthy weight loss generally involves a caloric deficit of about 500 calories per day. To achieve that, you could either run for roughly 5 miles or switch out your morning blended coffee drink for a cup of straight, black coffee. The choice is obvious.
“In general, with high-volume physical activity of at least four to five hours per week, combined with no change in your nutrition and no anti-obesity medications, you can expect exercise to add about 3 kilograms or 6.6 pounds of weight loss over the course of four months,” explains Dr. Deborah Bade Horn, president of the Obesity Medicine Association and medical director of the Center for Obesity Medicine and Metabolic Performance at the University of Texas. “For most individuals, this would be a discouraging weight-loss path.”
While in the grand scheme of things, the caloric burn you get from exercise isn’t huge, exercise is still critical to making sure that the weight you lose is from fat, not muscle, and helping you keep the fat off over the long term.
“Based on current clinical data, individuals that are dieting without exercising to lose weight will lose 3 to 4 pounds of muscle for every 10 pounds of weight that they lose,” Bade Horne says. “In other words, 30 to 40 percent of the weight that they lose is healthy, strong lean muscle instead of fat.”
While less than ideal on its face, once you consider the implications of losing muscle, you realize it’s a complete assault to your weight-loss progress. Muscle is the single greatest modifiable factor in setting your basal metabolic rate, or the number of calories you burn each day just to stay alive, and research out of Columbia University shows that losing just 10 percent of your body weight results in a significantly lower basal metabolic rate.
This makes continuing to lose weight, as well as keeping it off once you reach your goal, an enormous biological challenge. (Another study found that, to maintain their weight loss, former contestants on “The Biggest Loser” had to eat as many as 800 fewer caloriesper day compared to same-sized people who had never lost weight.)
“Fortunately, exercise, particularly resistance exercise, adds muscle to help counteract any potential drop in metabolism,” explains Dr. Micah J. Eimer, co-director of the sports cardiology program at the Northwestern Medicine Bluhm Cardiovascular Institute. For example, in one 2016 study published in The American Journal of Clinical Nutrition, men who combined a low-calorie, high-protein diet with high-intensity resistance training were able to effectively burn 10.56 pounds of fat while gaining 2.64 pounds of lean muscle.
More Weight-Loss Benefits of Exercise
When it comes to losing weight, the benefits of exercise extend far beyond keeping your muscle mass and metabolism up. In fact, research published in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology shows that exercise may also prevent weight regain by preventing the formation of fat cells, encouraging the body to burn calories from fat and keeping cravings at bay.
According to Eimer, exercising triggers the release of powerful satiety hormones. What’s more, people who exercise tend to have an easier time following their healthy eating plans compared to sedentary adults. After all, in one New England Journal of Medicine study of 50 overweight adults, following a low-cal diet for just 10 weeks significantly lowered their levels of leptin, a hormone that helps you feel full, for up to a year later. Exercise can help mediate the damage.
Diet and Exercise: Your Best Strategy for Losing Weight and Keeping It Off
For weight loss that lasts, combine diet and exercise. Focus on achieving a mild caloric deficit (around 500 calories) through your eating plan. And then make your workouts all about building metabolism-boosting muscle, recommends Dr. Spencer Nadolsky, a board-certified family and bariatric physician, diplomate of the American Board of Obesity Medicine and author of “The Fat Loss Prescription.”
To keep track of your progress and make sure that you are losing fat, not muscle (learn how to gain muscle while losing weight), Bade Horne advises ditching the regular bodyweight scale for one that also measures body-fat percentage. If, as your weight declines, you see your body fat percentage staying the same or, even better, decreasing, you know that you’re on the right track for lasting weight loss.