Most beginners go to the gym with the aim of ‘turning fat into muscle’ – that is, they want to lose weight and get in shape at the same time. However, in terms of metabolism, fat is fundamentally different from muscle – and the body cannot replace one kind of tissue with another.
On the other hand, increasing muscle mass definitely helps burn fat, both by increasing calorie needs and by producing testosterone and growth hormone. In other words, getting in shape and losing excess weight is still realistic – but with a few rules.
Fat versus muscle – a comparison
Fat is an energy store that the body uses as a passive balance, while muscles are metabolically active and need energy to function. The more muscles in the body, the more calories are spent to maintain them.
Even though muscles can hide under a layer of fat that stores thousands of calories, when you strength train, your body will never use the energy of the surrounding fat to maintain muscle. The reason for this is simple – muscles don’t essentially work on fat but on carbohydrates.
Strictly speaking, it is virtually impossible to get the body to first burn fat in one workout and then use the energy released to build muscle. In fact, they are two completely different and mutually exclusive physiological processes.
Glycogen and energy for training
In the first 30-50 minutes of any workout, the body uses glycogen, which is stored in muscles and is a product of digesting carbohydrates from food. It is estimated that a person needs between 80 and 150 glycogen per workout.
Only when glycogen reserves are depleted does the body switch to other energy sources – proteins and fats. More specifically, to muscle and free fatty acids. In this case, the order is most often glycogen, muscle, and fat. In other words, the body only starts burning fat last.