Fitness Tips


Body Fat v. Lean Muscle Mass
A lot of Lazy Runners ask me about their body fat percentages in the testing week and how it is figured out, so I thought a tip this week would be relevant.

People of the same height and weight can have a very different body composition.

The human body is made of many different tissues; mostly it is water, bone, lean tissue and adipose tissue (fat). When we talk about the body fat percentage it is just that, the amount of fat in our bodies, however it is not just the chubby skin fat we can pinch, it is also made up of visceral fat, that is the fat that lines our organs and internal fat.

The way I measure your body fat is with the bioelectrical impedance analysis (BIA) system. I use this method at it is easy, less invasive and cheaper than other methods, however, it is not as accurate, but done regularly can give you an idea of how your body fat and muscle levels are going.

Generally BIA is a small electrical current that is sent through the body (in our case through the feet); the resistance to the electrical stimulus is different when it encounters fat and when it encounters lean muscle and also skeletal tissue.

Muscles are a good electrical conductor as they have a high percentage of water, however fat is a poor conductor. Some inaccuracies with the BIA are the amount of water you have consumed prior to the test or your general hydration levels, as electrical currents travel better through water, more fluid may give you a lower body fat reading.

It can also be affected by alcohol, caffeine the amount of exercise you have done prior to testing, if you have eaten just prior to testing and for women the time of the month. The best time to do the BIA is in the morning before eating, drinking and exercise.

However you really need to be aware that is just a tool to use to see if your exercise and eating regime is working in the manner you wish ,which should be to reduce body fat and build lean muscle.

You will have noticed that men are required and often do have a lower body fat percentage to women. This is due to women carrying more adipose tissue in the body,  women’s breasts are all adipose tissue and they carry more fat in their hips as well. Men have bigger muscles and therefore the percentage of muscle should be a lot more than their fat percentage.

If you are looking for the ideal body composition-

Everyone should have more percentage of muscle than fat in their body.

Women's body fat should be a third less than her muscle mass, and men's should be halve their muscle mass. Men usually have a higher hydration reading as they store more fluid in their muscles and as I said men’s muscles are bigger and that means more water is pumping them up.

The older we get the more body fat we are allowed to have to still remain in the healthy range this is due to the fact that the visceral fat (internal fat) increases, and our muscle mass decreases.

A certain amount of fat is essential to bodily functions. It regulates your body temperature, protects and insulates organs and other tissues and is the main form of the body's energy storage. However the essential fat for women is around 10-12% and for men it is only 2-4%.

Another important point to note is that body fat or adipose tissue is inactive, oh it may wiggle and jiggle a bit, but it doesn’t work the way muscles do. Adipose tissue is what is termed metabolically inactive, the means it doesn’t work hard or strengthen or burn a lot energy. Muscle has the ability to do that; they therefore burn a lot more calories that fat.

Muscle when worked burns double the amount of calories than fat, therefore if you have more muscle you will burn more calories when exercising.

That is often why lean, muscular people seem to be able to eat all they want and still stay lean and of course some of us just look at a muffin and our trousers tighten up! Another point is that fat takes up to four times as much space in the body as lean muscle, so it makes you look chubbier as well, even if it is not showing up on the scales as kilos.



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