Are You Burning Fat When You’re Working Muscles?

Searching the Internet for fitness and health can be a daunting experience, from an overdose of information to often misleading advice. This series aims to shed light on these hard-held beliefs still circulating in the fitness industry today.

The burning feeling while working a muscles means it’s burning fat.

The burning sensation is simply lactic acid produced when a muscle is under tension for more than 15 seconds and has used up its immediate energy stores. It is NOT fat that is being burned.

A muscle has three main systems to produce the energy needed to work the muscles.

The first system is immediate and the energy lasts for 15 seconds. The second is quick, with the energy supply lasting for less than two minutes, but it produces lactic acid as a waste product. And the third system is slow to produce energy but it supplies the most of all.

Any fitness activity relies on all three systems, which work continuously together to produce energy. The burn we feel is exactly the lactic acid produced from system two. This acid is eventually flushed out and used as energy as the activity proceeds. When too much acid is produced and the muscles cannot flush it out fast enough, fatigue sets in and the muscles cannot contract properly.


One cannot sense what he or she is burning as fuel for energy (sugars or fats). The workout determines which source of energy and which system is preferred. Tolerance to lactic acid and the burning feeling increases as one trains more consistently.
  • For beginners, remind yourself that you will, with time, be better able to handle the achy feeling that the burn produces.
  • Some workouts are designed to produce that sensation because of the training benefits of these types of workouts. Take the challenge.
  • Unless you’re well trained, it’s difficult to resist the burn, so instead of stopping an activity, try to take active rests (for example working a different muscle or doing some full body moves like burpees) every now and then, until you’re there.
  • The best way to flush out acid is to keep moving. So don’t stop the workout half way through.

Stay tuned for more fitness myths in our upcoming issues.


You Might Also Like