When it comes to changing your body composition, the scale is by far the most primitive tool we have. Basing your entire progress on overall weight loss will lead you astray, as it cannot distinguish between losing fat, water weight, and that invaluable lean muscle mass. The moment you switch your goals from ‘lose weight’ to ‘build muscle, and lose fat, you change your definition of health, longevity, and physical functionality altogether. Focusing on lean mass instead of just seeing a smaller number on the scale completely changes your body’s response to nutrition and stress. Below are 8 reasons why your lean body mass is far more important than just your weight:
It Protects your Joints

Your muscles are the primary shock absorbers for your skeleton. Increased lean mass means that your muscles can stabilize joints effectively, absorbing the impact of daily activity, thereby preventing wear and tear and long-term joint damage.
It provides Structure and Posture Alignment

Muscles help keep your skeletal system upright, aligned, and in the correct posture. Weak core muscles, for example, often lead to anterior pelvic tilt, which causes issues with spinal and lumbar posture. Increasing lean mass balances your skeletal structure, thus providing you with an improved posture and reducing strain on the spinal cord.
It Strengthens the Immune System

Muscle is a storage area for the majority of the body’s amino acids. Amino acids are crucial for the immune system and can be used to form immune cells or as an energy source when illness or injury occurs. Greater muscle mass provides a greater supply to fuel your immune system response during a time of need.
It can decrease the all-cause Mortality Risk

It is statistically proven that people with a higher lean body mass live longer and have a reduced risk of chronic disease and subsequent mortality, compared to individuals with a lower relative lean mass.
It facilitates Healthier Weight loss

By implementing weight training within your program while also partaking in a caloric deficit, any weight you lose will most likely be from body fat. You will be left with a leaner physique with a better body composition rather than what is sometimes referred to as ‘skinny fat’.
It improves Cognitive Function

There are many connections between your muscles and brain. When muscle mass contracts, it releases myokines into the bloodstream; these molecules cross the blood-brain barrier, improving the function of and aiding the health of the brain. Myokines are shown to promote neurogenesis and plasticity as well as improve mood.
It increases Everyday Vitality

Muscle power can translate into functionality during everyday life, such as carrying shopping, walking up stairs with a load of things, chasing children, carrying heavy items during domestic chores, etc. This is particularly important for everyday enjoyment and life satisfaction.
It changes Body Composition

Body weight alone does not represent the physical structure or ‘tone’ of the body. The muscle is 1.5 times as dense as fat, and so for the same pound on the scale will result in a significantly smaller waistline and a more toned physique, giving you an athletic and highly functional build.