BMR Inputs

Basal Metabolic Rate is the minimum calories your body needs to sustain vital functions at complete rest — breathing, circulation, cell repair. It accounts for 60-75% of total daily calorie burn for most people, making it the largest component of your energy budget.

The Mifflin-St Jeor formula (used here) outperforms the older Harris-Benedict formula in most studies, with mean error under 10% vs measured metabolic rate. The Katch-McArdle formula is more accurate if you know your lean body mass, since it accounts for muscle mass directly.

Yes significantly. Skeletal muscle burns approximately 6 calories per pound per day at rest, compared to 2 calories per pound for fat. A person with 140 lb of lean mass has a meaningfully higher BMR than someone of identical weight with 115 lb of lean mass.

BMR decreases. Severe restriction (below 25% of TDEE) can trigger adaptive thermogenesis — metabolic adaptation that reduces BMR by 5-15% beyond what weight loss alone predicts. This is why gradual deficits and diet breaks help long-term fat loss.

Yes. Building muscle through resistance training is the most effective method — each pound of muscle raises daily BMR by approximately 6 calories. Adequate protein intake (0.7-1g per lb of body weight) also prevents BMR-reducing muscle loss during weight loss.