One of the most commonly held BELIEFS in both the bodybuilding/fitness industry and in the general population is that you need/should do steady state/low intensity cardio on an empty stomach (fasted state) as you will burn more fat. Well finally that myth has been officially DEBUNKED! Ive been saying this for years (as have many others in the science world) that it does not matter when you do your cardio as what matters is what happens over the 24 hour period. Fat oxidation levels are no different if you do your cardio in the morning before breakfast or in your lunch hour or after work in the evening. Its the total energy expendature that counts!! Body composition changes associated with fasted versus non-fasted aerobic exercise. Abstract It has been hypothesized that performing aerobic exercise after an overnight fast accelerates the loss of body fat. The purpose of this study was to investigate changes in fat mass and fat-free mass following four weeks of volume-equated fasted versus fed aerobic exercise in young women adhering to a hypocaloric diet. Twenty healthy young female volunteers were randomly assigned to 1 of 2 experimental groups: a fasted training (FASTED) group that performed exercise after an overnight fast (n =10) or a post-prandial training (FED) group that consumed a meal prior to exercise (n =10). Training consisted of 1?hour of steady-state aerobic exercise performed 3?days per week. Subjects were provided with customized dietary plans designed to induce a caloric deficit. Nutritional counseling was provided throughout the study period to help ensure dietary adherence and self-reported food intake was monitored on a regular basis. A meal replacement shake was provided either immediately prior to exercise for the FED group or immediately following exercise for the FASTED group, with this nutritional provision carried out under the supervision of a research assistant. Both groups showed a significant loss of weight (P =0.0005) and fat mass (P =0.02) from baseline, but no significant between-group differences were noted in any outcome measure. These findings indicate that body composition changes associated with aerobic exercise in conjunction with a hypocaloric diet are similar regardless whether or not an individual is fasted prior to training. Further comments by Brad Schonfeld (one of the researchers & authors)- We tried to do a subanalysis but with the small n it simply didnt warrant significance. In looking at those who were sub-20% there did not seem to be any benefits conferred under fairly well-controlled conditions. We did acknowledge in the limitations section that it remains possible a small benefit may be conferred for those who are very lean. The one thing that appears clear is that any effects, if they do exist, would be relatively minor. The issue with HIIT in this context is that it is counterproductive to the fasted cardio theory. There is increased lipolysis at higher levels of aerobic intensity, but the capacity to oxidize the lipid maxes out and thus the FFA gets re-esterified. The acute studies only show a benefit for oxidation when training at low to moderate intensities which is why we chose this intensity level.. This is not about HIIT per se, its about performing higher intensity aerobic exercise under fasted conditions. The issue is that the fasted condition allows for an acutely greater lipolysis during the HIIT, but that the overall oxidation rate is similar to the fed condition because more FFAs are available then can be oxidized. I cited this research in my 2011 review on the topic. And this from Jose Antonio - Both SSC and HIIT will work for fat loss. Also, if your goal is performance (not body comp), then youll typically see a ratio of roughly 80% steady state cardio and 20% interval training. This applies to high level endurance athletes (i.e. running, cycling, rowing, etc). And those guys are quite lean. The idea that one is better than the other is the wrong question. The better question is what utility does each form of training serve vis a vis the specific goals of the athlete.
Posted on: Tue, 18 Nov 2014 21:34:54 +0000
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