BMR and Weight Loss: What You Need to Know

Your BMR drops as you lose weight because a smaller body needs fewer calories. Extreme dieting can suppress BMR further through adaptive thermogenesis.

Metabolic adaptation

Losing 10% body weight may reduce BMR by 15–20% — more than predicted by size alone. This is the body defending against perceived starvation.

Diet breaks and refeeds

Eating at maintenance for 1–2 weeks after 8–12 weeks of dieting may partially restore leptin and BMR. Evidence is mixed but anecdotal support is strong.

Preserve BMR with resistance training

Strength training during a deficit signals the body to retain muscle tissue, which is metabolically active. Losing muscle accelerates BMR decline.

Minimum safe intake

Never eat below BMR for extended periods. If your calculated deficit puts you below BMR, reduce the deficit or increase activity instead.

When you are ready to calculate, use our free BMR Calculator — it runs privately in your browser and shows the formula used.

Frequently asked questions