How does fat burning work?

In nature, oxidation ie, burning takes place in the presence of oxygen. The same principle goes for the burning of fat stored in your body.

Your system uses nutrients carefully and in a very economical way. As you’ve seen above, there are 3 major kinds of energy sources that can be transformed into energy in the body: carbohydrates, proteins and fats.

Your body wants to use fat as a last resort. It will first use blood sugar from your blood and glycogen from the liver and muscles. During the digestive process, nutrients are transformed into glycogen by insulin and energy is stored in this form in the liver and the muscles.

While taking exercise, these glycogen stores get depleted. If you don’t exercise regularly, the surplus nutrients can only be stored as fat because the glycogen store is already full! This is what we call the process of getting fat!

If you get conscious about your food intake and eat less simple carbohydrates (ie, sugar), you’ll boost the fat-burning process as the blood sugar level has to be minimal for fat burning to kick in. So, fat burning will only start if carbohydrate stores have been depleted. This usually takes 30 minutes. Consequently, actual fat burning will start after the 30th minute of your training session. Therefore a fat-burning training session has to last 60 minutes because no actual fat burning takes place in the 1st 30 minutes.

However, there is a so called post exercise stage of fat burning by which fat burning continues for about 30-60 minutes after you finished your high-intensity physical activity.