Quote:
Originally Posted by Pepino
Personally, I don't like fasting as a weight loss aid. When you fast, your body is forced to breakdown YOUR MUSCLE as a protein source. So then, when you're done your fast and go back to regular eating you have LESS MUSCLE even if you worked out hard during those days. Not worth it to me. I want to be toned and healthy...not thin and sickly. I also think this is worse for a woman to do than a man because it takes men a LOT less time and effort to quickly rebuild any lost muscle because of their testosterone.
This is not true.
http://www.leangains.com/2010/10/top...-debunked.html
"6. Myth: Fasting causes muscle loss.
Truth
This myth hinges on people's belief it's important to have a steady stream of amino acids available to not lose muscle. As I explained earlier, protein is absorbed at a very slow rate. After a large high-protein meal, amino acids trickle into your blood stream for several hours.
No studies have looked at this in a context that is relevant to most of us. For example, by examining amino acid appearance in the blood and tissue utilization of amino acids after a large steak, veggies and followed up with some cottage cheese with berries for dessert. That's easily 100 grams of protein and a typical meal for those that follow the Leangains approach. We are left to draw our own conclusions based on what we know; that a modest amount of casein, consumed as a liquid on an empty stomach is still releasing amino acids after 7 hours. With this in mind it's no stretch to assume that 100 grams of protein as part of a mixed meal at the end of the day would still be releasing aminos for 16-24 hours.
Few studies has examined the effects of regular fasting on muscle retention and compared it to a control diet. None of them are relevant to how most people fast and some are marred by flaws in study design and methodology. Like this study which showed increased muscle gain and fat loss, with no weight training or change in calorie intake, just by changing meal frequency. While I would love to cite that study as proof for the benefits of intermittent fasting, body composition was measured by BIA, which is notoriously imprecise.
Only in prolonged fasting does protein catabolism become an issue. This happens when stored liver glycogen becomes depleted. In order to maintain blood glucose, conversion of amino acids into glucose must occur (DNG: de novo glucogenesis). This happens gradually and if amino acids are not available from food, protein must be taken from bodily stores such as muscle. Cahill looked at the contribution of amino acids to DNG after a 100 gram glucose load. He found that amino acids from muscle contributed 50% to glucose maintenance after 16 hours and almost 100% after 28 hours (when stored liver glycogen was fully depleted). Obviously, for someone who eats a high protein meal before fasting, this is a moot point as you will have plenty of aminos available from food during the fast."