Among the researchers that stand out for performing practical and innovative studies the Paoli group accompanied men trained for 24 hours after performing aerobic exercises (36 ‘to 65% of VO2 max) before breakfast. Some choose to exercise fast because they believe it helps metabolize more fat, but Science questions the real significance of this, as Paul Gentile writes in his book on Weight Loss. When the exercise is performed in fasting, the practitioners spend less energy at rest for another 24 hours after the end of the exercise. As if the body activated an emergency mechanism that leads it to save energy after fasting exercise. And the most impressive is that in the 24 hours after the fasting exercise there was less fat oxidation, that is, the body does not only seek to save energy, it also fights to preserve and even accumulate fat !!! Many people may wonder, then, why there are so many people reporting results with fasting exercise. The answer may lie in the fact that this leads them to ingest less calories throughout the day, putting them in marked energy deficit. But then the problem would be the induction of protein catabolism (loss of muscle mass) and a still severe reduction in metabolism. So why does not this happen in this galley? Because most make massive use of pharmacological (anabolic / stimulant) resources that preserve lean mass and increase metabolism. My suggestion is to use more intense exercises that will naturally increase metabolism and fat utilization for hours after the end of the exercise.