The 20 Minute Rule

Have you ever been told that it takes 20 minutes of cardiovascular exercise in order to burn body fat?  This is both true and false.

Your fat cells continually release fatty acids that are being burned within your muscles no matter what you're doing, even sleeping. The amount that is being released and burned is very very small, or more like a trickle.  When you start to exercise your muscles need more than a trickle of energy for the task at hand.  Your muscles send a message to the fat cells to release more fatty acids. 

Compared to the other 2 macronutrients, carbohydrates and protein, fat has more "energy" per gram.  It's a great source of "fuel" for the body.

But our bodies are smart.  Our bodies prefer homeostasis.   Homeostasis in a general sense is the body's attempt to maintain a constant internal environment. Maintaining a stable internal environment requires constant monitoring and adjustments as conditions change.

Because the human body prefers a homeostatic state, it is going to resist releasing the fatty acids to the muscles until you've been working out for twenty or thirty minutes.  Then suddenly your fat cells release a gush of fatty acids. The fatty acid level in your bloodstream increases to meet the demand.

If you workout regularly and are fit then your body will start to burn fat almost immediately at the start of your workout. The less fit you are the longer it will take (20 - 30 minutes of continuous exercise) before your body hits a higher level of fat burning.  Basically a fit person's body is more efficient at burning fat than an unfit persons.   

We have train our bodies to be fat burning machines by working out regularly.  So go get some exercise!