How much exercise do I need to lose weight?
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More than you need for health, and food sets the pace either way. The American College of Sports Medicine found that 150 to 250 minutes a week of moderate exercise brings only a modest loss, and more than 250 minutes, a bit over 4 hours, went with a clear one. Your body also makes up about 28% of what extra activity burns.
The treadmill shows a big calorie number, which feels like a meal earned, and a month of that should show on the scale. When it barely moves, people decide exercise doesn’t work for them and stop. Exercise burns less than it feels like, the body claws some of it back, and the 150 minutes that do so much for your heart do less for your weight.
What we’d do
Use food to lose the weight, and exercise to keep your muscle and keep the weight off once it’s gone. Walk most days, lift twice a week, and don’t eat back the calories your watch says you burned. If you want exercise to do more of the work, build toward 4 to 5 hours of brisk walking a week and expect it to take months.
Losing weight with exercise alone is like bailing out a boat with a cup while the tap is still running. The cup helps, and turning down the tap is faster.
What did the ACSM find?
In 2009, the American College of Sports Medicine reviewed a decade of studies on exercise and weight for adults with overweight:
| Moderate exercise a week | What the evidence showed |
|---|---|
| 150 to 250 minutes | Prevents weight gain, and brings only a modest loss |
| 150 to 250 minutes, with a moderate diet | Adds to the loss from the diet |
| More than 250 minutes | A clinically significant loss |
| More than 250 minutes, after a loss | Linked to keeping it off, though no good trial has tested it |
Lifting didn’t add to weight loss in the studies it reviewed, but it may increase lean mass and the share of the loss that comes from fat, which is the part you want to lose.
Why does the scale move less than the treadmill says?
Part of the burn gets made up. In 2021, researchers pulled together energy measurements from 1,754 adults living their normal lives, taken with a lab method called doubly labeled water. On average, the body made up about 28% of the extra calories burned through activity by burning less at rest. Only about 72% of the extra burn showed up in the day’s total, and people with more bodyfat made up more of it.
Even so, exercise alone does move weight. In the Midwest Exercise Trial 2, 141 young adults with overweight or obesity did supervised exercise five days a week for 10 months, with no diet changes. The two exercise groups lost about 4% and 6% of their body weight, and the group that didn’t exercise gained a little. That’s real, and slower than most people hope. bodyfat.guide covers the rest in why am I not losing weight when I exercise?
What about the calories my watch shows?
tdee.guide covers calories, including the ones on your wrist. Watches are good at heart rate and much weaker at calories, as tdee.guide shows in is Apple Watch calorie burn accurate?, and it explains why eating them back stalls a diet in eat back your exercise calories. For running, its page on calories in a mile walked or run has the numbers for your weight.
4 sources
- Donnelly JE and others, American College of Sports Medicine position stand: appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults, Medicine and Science in Sports and Exercise, 2009europepmc.org
- Careau V and others, Energy compensation and adiposity in humans, Current Biology, 2021europepmc.org
- Donnelly JE and others, Aerobic exercise alone results in clinically significant weight loss for men and women: Midwest Exercise Trial 2, Obesity, 2013europepmc.org
- bodyfat.guide, Why am I not losing weight even though I work out?bodyfat.guide
