Fasting, or periods of very little food, may have benefits other than weight-loss photo: pixabay/publicdomainpictures

Fasting: more than just a fad diet?

Congratulations, you’ve survived an eventful term one at Warwick! In a couple of day’s time, most of us will be returning to our respective corners of the world. And let’s be honest, while student life can be a blast, we’re all counting down the seconds until we get home to a warm, home-cooked meal.

Mentally, you may already be planning a food orgy of disgusting/delicious proportions for the duration of this winter break (because come 2013, you’ll definitely stick to your dieting resolutions). Intermittent fasting, the practice of alternating periods of no or very reduced food intake with periods of normal or unrestricted food consumption, may be a better option though, and not just for short term weight loss.

Fasting brings about certain biochemical and physiological changes in the body. The process begins 10-12 hours after you consumed your last meal, when all available glucose in the blood is used up to fuel energy requiring processes. At this point, the liver and muscle cells start converting their stored glycogen into glucose, subsequently releasing it into the bloodstream. 3 to 4 days after the new diet begins, your body’s metabolism has transitioned to using your fat reserves as the main energy source, since the glycogen stores have been depleted. Your brain, which usually has a high requirement for glucose, is now using ketone bodies as its primary fuel source; these are the by-products of fatty acid breakdown by the liver.

Perhaps most importantly, at least from a health perspective, fasting results in a decrease in the production of certain hormones. Notable examples include insulin and insulin-like growth factor 1(IGF-1). High levels of both of these hormones have been associated with an increased risk of developing cancer. In addition, high insulin levels increase your risk of type II diabetes and cardiovascular disease. Fasting not only reduces the levels of these hormones, it has also been shown to reduce body weight, heart rate, blood pressure and LDL cholesterol levels. All of these risk factors normally predispose an individual to a multitude of health problems.

Studies conducted with both animals and humans have shown that fasting could help maximize the benefits of cancer treatments. In one study with mice models of glioma – a form of malignant brain cancer – a 48-hour fasting period made the tumours more sensitive to radio- and chemotherapy than the tumours in non-fasting mice. The mutations that usually confer an advantage to cancer cells under physiological conditions are thought to be detrimental under fasting conditions.

Furthermore, fasting has been associated with a reduction in severity of asthma, as well as with a delay in the onset of certain neurodegenerative disorders such as Parkinson’s and Alzheimer’s. In a study from the US National Institute of Aging, mice models for Alzheimer’s disease showed a 6 month delay in the onset of Alzheimer’s-like symptoms when they were subjected to an alternate-day fasting diet.

There are a number of different fasting regimes in common practice. The 5:2 diet, for instance, advocates that you only eat a single meal of 600 calories on two days of the week. On the remaining five days, you are free to eat what you like, though you should stick to the guideline amounts of 2000 and 2,500 calories for women and men, respectively. The alternate-day fasting (ADF) diet requires that you alternate a 24h period of fasting partially (i.e. eat a single meal of about 600 calories) or completely with a 24 h period where you are free to eat anything. Somehow it’s still doubtful that this includes deep fried snickers bars. Finally, you can undergo periods of total fasting lasting from one to five days. You should never carry on fasting for longer than this, as this will have serious health consequences.

Of course, it’s not as simple as it sounds. Say, for instance, you attempt the ADF diet. You may start out with the grim determination to stick to not eating for a day, but by the time four o’clock rolls around, your stomach is screaming at you and all your friends suddenly look like tasty, tasty hamburgers. Your vision feels blurry, there’s a pounding in your head and the Grinch has got nothing on you in terms of grumpiness. This is your body adjusting to a different diet and can last from 10 days up to 3 weeks after you started the intermittent fast. If you do manage to stick to the fast for the day, you may feel tempted to binge the next, effectively undoing any of the benefits from the day before.

Overall, the practice of fasting shows promise as a potential prophylactic measure for many diseases. However, much research must still be done to determine the best fasting regime for humans, and which target groups should consider undergoing such a rigorous regime. Before you consider undergoing such a regime, you should research extensively and perhaps even consult with your GP. More information can be found in this New Scientist article: http://www.newscientist.com/article/mg21628912.400-deprive-yourself-the-real-benefits-of-fasting.html?full=true

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