Do you now.
It’s usual at this point to present a load of reasons and/or evidence as to why this is not actually the case and that exercising in a ‘fasted’ state is a total fitness fallacy.
However, there are several studies* that have shown that exercising after eating does indeed inhibit the oxidisation of fat for fuel (fat burning). The basic reason for this is that eating carbohydrates actually prevents long chain fatty acids entering the mitochondria (the aerobic power house of your cells) therefore reducing the amount fat that is broken down for fuel.
On the face of it, the issue is cut and dried. If we all want to be lean, athletic and svelte we should get up and train tomorrow with nothing in our stomach.
The results of several other studies have, frustratingly, indicated that training after a meal has absolutely no effect on your ability to burn fat.
So why the discrepancies’? It all comes down the condition of the test subject and the duration of the exercise. The studies that showed fasted cardio is more effective for fat burning in those people who are less fit and subsequently likely to train for a shorter period of time. So, be honest. Are you a little out of shape and relatively new to regular training?
Try exercising first thing in the morning on an empty stomach. You may experience more fat loss.
Have been training regularly for 6-12 months and do your training sessions last an hour or more?
Eat before you train as it will energise the intensity and duration of your session without having any negative effect on your ability to burn fat for fuel.
As always this is a simplistic take on a complex subject. We aim to eliminate some of the confusion surrounding the things you may hear about health, fitness and nutrition. We want you to make informed decisions based on the current relevant research. Know your training goals, know why you are training and eat (or not) accordingly.
*Substrate metabolism when subjects are fed carbohydrate during exercise.
Horowitz JF1, Mora-Rodriguez R, Byerley LO, Coyle EF.
Am J Physiol. 1997 Aug;273(2 Pt 1):E268-75.
Fatty acid oxidation is directly regulated by carbohydrate metabolism during exercise.
Coyle EF1, Jeukendrup AE, Wagenmakers AJ, Saris WH.
**Carbohydrate feeding during prolonged strenuous exercise can delay fatigue.
Coyle EF, Hagberg JM, Hurley BF, Martin WH, Ehsani AA, Holloszy JO.
Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate.
Coyle EF, Coggan AR, Hemmert MK, Ivy JL.