What's lean muscle mass?

It is said that men usually have more lean than women. I would like to know what does the 'lean muscle mass' mean? is it just the muscle mass? How would you calculate it?

Consider an example, a person X who's weight is say :90 kg.
Then consider another person Y who's weight is also :90 kg.

Both have same weight, BUT, X has more lean mass than Y. What does that mean?
it means your bodyweight is a sum of different factors:

• Your body fat mass (fat percentage)
• Your body muscle(lean) mass (muscle percentage)
• Bones
• etc..

Lean mass is thus the pure muscle mass without the fat. Men have more lean mass than women , because their body composition and physiology has more muscles, particularly in the upper body. Thus it makes the muscle's percentage higher than the one in women.

To calculate your lean mass you need first to measure your body fat percentage. You can do this using machines (some are not very accurate) or using a caliper. The caliper is the fastest and cheapest tool you can have.

Check out this video on how to use a caliper, and this link to enter your measured data and use the calculator to get your body fat percentage and lean mass.

Remember two things:

• you will need some help to take the measurements
• This method is an estimate, always consult a doctor for the best most up to date technique
• I'm big boneded. Commented Jun 9, 2012 at 14:48
• Do you lose lean mass or body fat when your body is running short on carbohydrates?
– cpx
Commented Jun 10, 2012 at 18:22
• @cpx the loosing fat/lean mass is a complex topic, but in a brief ur body uses carbs as fuel, so if short on fuel it will use its fat. You won't lose lean mass unless ur not eating at all or ur barely having protein and doing a strict diet. Then ur body will use its fat first then start consuming muscles for energy to survive (this is in extreme starvation diets)
– ccot
Commented Jun 10, 2012 at 20:20