RMR (Cunningham)

The Cunningham equation estimates resting metabolic rate from lean body mass, the body tissue that is metabolically active and drives most calorie use at rest. It works well because muscle, organs, and other fat-free tissues need energy even when you are not exercising, so people with more lean mass usually burn more calories. This makes it especially useful when body composition matters more than body weight alone, such as in athletic or very muscular individuals.

Use this when you want a resting calorie estimate for someone whose lean mass is known or can be estimated, especially athletes or people with atypical body fat levels. It is less appropriate if you only know total body weight and have no reliable lean-mass measurement.

• Using total body weight instead of lean body mass
• Forgetting to keep lean body mass in kilograms
• Treating the result as total daily calorie needs rather than resting metabolic rate only