Exercise is Everything

If you don’t exercise, your body composition will alter over the years, even if you don’t change your eating habits at all. As I’ve already said, muscle is an active tissue that is designed to be used—to support the skeleton and to enable us to move. When we are using our muscles, we maintain the same LBM. If we stop using them or use them less, they will start to literally waste away. The individual muscle fibers become smaller and so require less fuel to function. This means, quite simply, that we then need to eat less.

Compare this to the engine in a car. Imagine a large luxury car with a very powerful engine. This engine would need a lot of fuel. You may get as few as 15 miles per gallon from this engine, so the tank needs to be very large. Let’s say this car’s gas tank holds 15 gallons. Now imagine a small hatchback with a much smaller, less powerful engine. This engine requires less gasoline, and you may get as many as 40 miles to the gallon out of the car. As a result, there’s no need to put in as much gas,and the tank doesn’t need to be as big. It may hold a maximum of 10 gallons, so if you tried to put in 15, it would overflow.

Now let’s compare this to our muscles. Muscles that are constantly being used require lots of energy—in other words, food, for which they have large storage tanks within the muscle itself. These tanks are constantly being emptied and refilled. On the other hand, muscles that are not constantly used become smaller. They literally shrink, and their storage tanks shrink accordingly. So what happens if we try to put in the same amount of fuel that we put in our large muscles? It overflows. The body has a very effective way of mopping up this overflow—it takes the leftover fuel and stores it as fat.

The amount of muscle will determine how much food the body needs in order to function efficiently. If we lose muscle through lack of exercise, we should reduce the amount of food we eat accordingly. If we don’t, as we get older, we will be eating more than our bodies require and creating a surplus. This surplus will be stored as fat.