Recent paper on fat metabolism during exercise

Mr_Knight

All kinds of interesting tidbits in here. I apologize if this has been posted before - I did look but the MFP search is pretty hopeless. The most interesting conclusion is that for subjects in an energy balance (i.e. neither caloric deficit nor surplus), the amount of fat oxidized over a 24H period is independent of the amount or type of exercise.

"Before commencing these studies, our hypothesis was that fat oxidation would be elevated on days when exercise was performed, and that fat oxidation would be higher in endurance-trained individuals. To our surprise, we have found that exercise has little, if any, effect on 24-h fat oxidation."

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2885974/

"It is widely assumed by both the scientific community and the general public that high levels of physical activity and exercise would induce an increase in fat oxidation and therefore negative energy balance. Our studies would suggest that energy and macronutrient intake is a more important modulator of daily fat balance, and therefore, that exercise recommendations made for the sake of regulating fat mass cannot be made without also considering energy and macronutrient intake."

"If acute exercise and chronic exercise training induce changes in skeletal muscle that favor an increase in fat oxidation, why doesn't 24-h fat oxidation increase when exercise is performed? The most likely factor is the effect carbohydrate intake on lipolysis and fat oxidation."