More and more I hear people around me talking about fasting and my question was: Why does it work and how does it work? Had this conversation with Andy once a while ago and always kept that in the back of my mind. Andy told me that he used to do it every once in a while and explained a lil bit. I thought it was cool but didn't really know the benefits of fasting. So I did some research! Study after study shows that whatever you want to call the protocol – intermittent fasting, fasting, alternate day fasting, or alternate day caloric restriction – it works very well for weight loss. But does fasting work solely through caloric restriction, or is it doing something special? That’s the real question. There’s no question that fasting causes weight loss through caloric restriction. Obviously, when you don’t eat anything, your body turns to its own stored energy reserves, reserves that take up physical space and have mass. Depletion of those energy stores reduces mass and thus weight. Total and absolute caloric restriction. That’s elementary stuff and studies from the 1960s show that. To dig a bit deeper, let’s look at how weight loss occurs during a fast. Secretion of growth hormone, one of the premier fat burning hormones, increases during a fast. In a five-day fasting protocol, men experienced increased GH secretion on day one and day five (the only two days where GH was measured). A later study showed that during two-day fasting sessions, growth hormone secretions increased in both frequency and intensity in men. They experienced more frequent GH bursts and each burst secreted a higher mass of GH. A more recent study found that 24-hour fasts increased GH by 1300% in women and almost 2000% in men. Fasting decreases fasting insulin levels. The presence of insulin inhibits lipolysis, the release of stored triglycerides (body fat). Without lipolysis actually releasing stored body fat, it’s rather difficult to, well, burn that body fat for energy. During a fast, fasting insulin decreases and lipolysis increases. This insulin-blunting aspect of fasting quite literally allows the fast to be successful, because without the ability to access stored body fat for energy, making it through a period of zero caloric intake will be nigh impossible. Fasting improves insulin sensitivity. 20-hour fasts were enough to improve insulin sensitivity in men. Fasting increases the catecholamines, both adrenaline (epinephrine) and noradrenaline (norepinephrine). Both catecholamines increase resting energy expenditure during a fast, and guess where your fasting body finds the energy to expend? From body fat. Catecholamines activate hormone sensitive lipase present in adipose tissue, spurring the release of said fat. This makes intuitive sense, doesn’t it? If you’re hungry in the wild, you need to hunt (or gather, or fish, or somehow procure food) and you need energy to do it. The catecholamines help provide some of that energy while burning fat in the process.
All those mechanisms dealt with fat burning specifically.
A recent study found that while fasting and caloric restriction are “equally as effective in decreasing body weight and fat mass,” fasting is “more effective for the retention of lean mass." It appears that fasting “works” in several different ways and is an effective way to lose body fat. Have you ever tried it? Did/does it work for you? I'd like to hear about your experiences! TUESDAY Tech: Snatch 3, 3, 3 Work up to sets of three, be very meticulous on the second pull and get under fast! WOD: 2011 Opens Snatch wod (2011.1) 10 minutes AMRAP: 30 Double unders 15 Power Snatches (75/45lbs) Have fun! Fancypants :)