Does Your BMR Change When You Lose Weight?
Understand how weight loss affects your metabolism and what to do about decreasing BMR as you get lighter.
Yes, Your BMR Decreases With Weight Loss
This is completely normal and unavoidable. When you weigh less, your body requires fewer calories to function.
Think about it: a 200-pound body has more cells, more tissue, and more mass to maintain than a 150-pound body. Less body = less energy required = lower BMR.
On average, your BMR decreases by about 20-30 calories for every 10 pounds you lose. If you lose 50 pounds, your BMR might drop by 100-150 calories compared to your starting point.
This is why people often say weight loss gets harder the closer you get to your goal—you're burning fewer calories at rest, so you need to eat even less or move more to continue losing weight.
Metabolic Adaptation: An Extra Slowdown
Beyond the normal BMR decrease from weighing less, there's another phenomenon called metabolic adaptation (or adaptive thermogenesis).
This is when your metabolism slows down MORE than expected based on your new body weight. In extreme cases, your BMR can drop 10-20% below what it 'should' be.
For example, if your BMR should be 1,400 calories at your new weight, metabolic adaptation might lower it to 1,250 calories.
This happens because your body is trying to protect you from what it perceives as starvation. It's a survival mechanism that helped our ancestors survive famines.
Metabolic adaptation is temporary and can be reversed with reverse dieting and maintenance periods.
How To Minimize BMR Loss
You can't prevent your BMR from decreasing as you lose weight, but you can minimize excessive metabolic slowdown:
Lose weight slowly (0.5-1% of body weight per week) to reduce metabolic adaptation
Eat enough protein (0.7-1g per pound of body weight) to preserve muscle mass
Strength train 3-4 times per week to maintain or build muscle (muscle burns more calories than fat)
Take diet breaks every 2-3 months by eating at maintenance for 1-2 weeks
Don't cut calories too aggressively (stick to 300-500 calorie deficits)
By following these strategies, you can keep your metabolism as high as possible during weight loss.
When To Recalculate Your BMR
You should recalculate your BMR and TDEE every 10-15 pounds of weight loss. Here's why:
After losing 10-15 pounds, your calorie needs have decreased enough that your original calorie target might not create a deficit anymore.
For example, if you started at 200 pounds eating 1,800 calories and lost 15 pounds, you now weigh 185 pounds. Your BMR and TDEE are lower, so 1,800 calories might now be your new maintenance instead of a deficit.
Recalculate using our calculator, adjust your calories accordingly, and continue tracking for another 10-15 pounds before recalculating again.