Fasting is one of the oldest methods for fast weight loss. You don’t need a degree in thermodynamics nor do you have to make any major changes in your lifestyle. You just stop eating, and maybe drink some water and juices, and voila! The numbers on the scale start going down. It sounds like a fantastic idea and there are a slew of New Age products on the market that claim to help you get the most out of your weight loss fast and support your efforts. Fasting is a simple and non-invasive method and is touted by some self-appointed experts as the cure to obesity, when used in conjunction with their products and services, of course. It could be a possible solution except for one small problem; it doesn’t really work. Yes, you do lose some weight temporarily, but most of the weight loss occurs simply as a result of the reduction in fluid retention that comes from not eating. A weight loss that is short-lived at best as it is will be inevitably regained within days of resuming your normal eating patterns. In the previous article we took a look at the questionable role of fasting in detoxifying your body, (see Fasting Does Not Detox Your Body) and in this article we will explore a bit more of what fasting actually does to our bodies and what role if any it may have in a healthy lifestyle.
Fasting & Weight Loss: Understanding the Mechanisms Of Short Term Fasts
One of the key aspects to understanding what happens during a fast is to have a clear picture of exactly what occurs in your body when you stop or restrict your food intake. Sugars broken down and stored in the form of glucose is our body’s main source of fuel and is essential not only for our muscles to work efficiently but also for our brain. When food intake is restricted, even within the context of everyday life for more than 4 to 8 hours, the low blood sugar levels trigger a rise in the hormones glucagon and epinephrine. These hormones, among other things, stimulate the conversion of glycogen–a form of glucose stored in our liver and muscles–into a useable form of fuel by means of a process called glycogenolysis. Our liver and muscles have enough glycogen to last for two to three days, which is one of the reasons brief periods of fasting, be it forced by circumstances or for spiritual reasons, are usually harmless for healthy individuals.
Studies have also shown that when used moderately in conventional spiritual practices, intermittent fasting does not seem to increase risk factors for eating disorders even in young teenagers who are most at risk. Fasting as a means of losing weight however has been long implicated as both a risk factor and symptom of eating disorders, especially in female adolescents. These disorders can have catastrophic effects on all the major organs of the body.[2,3] Most methods of fasting for weight loss last no longer than a day or two without some intake of food or juices which will supply much needed glucose to our bodies. That being said, there is no possible reduction in fat stores as the period of food restriction will not require our body to use fats as fuel. Any weight loss at this point will be due to the reduction in glycogen stores and water which will be quickly reversed when normal eating patterns return. Skipping a meal here or there thus, is not going to do anything to reduce the fat around your waist or anywhere else.
Fasting And Weight Loss: The Effects of Long Term Fasting
As we said, conventional weight loss fasting practices usually do not exceed a window of 24 to 48 hours without some intake of nutrients; however beyond this period our body will do its best to prevent the loss of skeletal muscle by using fats as a fuel. Fats from stored reserves in our body are broken down into glycerol and free fatty acids. Glycerol is used by the liver to help bring about gluconeogenesis (literally the new creation of glucose). The free fatty acids are used by your body as an energy source, but not your brain–as fatty acids cannot be used to fuel brain tissue because their molecules are too large to cross the blood-brain barrier. To meet the brain’s large demand for glucose your liver will begin to synthesize compounds called ketones. Ketones, made famous by advocates of low carbohydrate diets, are shorter chain derivatives of fatty acids, which are small enough to cross the blood-brain barrier and be used by the brain as a fuel.
The use of ketones as a fuel source for brain function is a stop gap mechanism by our body to reduce muscle breakdown during periods of food restriction. Given the historical reality of the countless famines and long periods without food endured by our ancestors for thousands of years, this mechanism makes sense as it allows us to have the energy to think clearly and be physically able to find food even in the face of long periods of starvation. The use of ketones reduces the brain’s requirements for glucose but cannot completely satisfy it over time. For the remaining fuel your body turns to the protein in skeletal muscle. Without food for several days all cells in your body begin breaking down proteins. This releases amino acids into the bloodstream which are then converted into glucose by the liver (gluconeogenesis). It should be noted, given what we know of the fasting process, that the fear that many have in terms of muscle loss from missing a meal or two is in fact unfounded. Many bodybuilders in lesser developed countries are able to build and maintain muscle mass with often as little as one meal a day. I can attest to this personally having started bodybuilding in Trinidad, where from time to time I would have no more than one meal a day without any negative impact on my overall muscle mass. It might not feel that great, but the idea that muscle wasting begins within hours of not eating goes a long way to sell protein shakes and bars, but contradicts the facts of human biochemistry.
Muscle wasting is a last ditch effort by your body to stay alive in the face of prolonged fasting and food restriction and is evident in anyone who has not eaten or had inadequate nutrition for extended periods of time ( i.e. weeks or months). As fat stores get smaller, more protein will be used up as fuel by the body–which eventually results in organ failure and death. The heart and other essential organs such as the kidneys fail as a result of tissue degradation, and such organ damage can occur in those with prolonged and untreated histories of eating disorders as well. A cursory look at what happens to our bodies when we don’t eat for extended periods of time make it obvious, given the low food stores available to us for the greater part of our time on the planet, that we would not be designed to easily shed fat and muscle stores.
Fasting and Health
Many would argue that since fasting has been such an integral (forced) practice throughout the millennia that it could indeed be used as a method for weight loss. However there are no long term, peer-reviewed studies to support this claim and all studies on fasting and weight loss are small, short in duration and provide little evidence in terms of long term results.  Results which can be obtained by following a consistent regime of proper diet and exercise. Dieting for weight loss purposes also tends to distract people from the changes in lifestyle required for optimal health and weight management, but it may have some uses outside of the realm of weight loss.
Studies have found that intermittent fasting may reduce harmful cholesterol levels,  risk of chronic disease  and may even increase the effectiveness of chemotherapy treatments. Since the dawn of modern medicine, fasting has been studied as a means of increasing overall health and longevity. Hundreds of studies have been conducted since to document this ancient method of health regulation and while rodent studies have shown increases in lifespan by 30-50%[10,11], no such studies have yet been confirmed in humans. The theory of caloric restriction as a way of prolonging life has many advocates in the health fields, however again no long term studies exist to confirm this and short term studies of caloric restrictions have reported ill effects such as loss of muscle mass, strength and bone mineral density. Studies of Mormons who fast at least once a month show that they tend to have a better life expectancy than the rest of the general population, but a similar finding in Seventh-Day Adventists suggests that fasting may have little or nothing to do with it. Members of both groups tend to make better choices in terms of their diet, patterns of regular exercise and avoidance of cigarettes and alcohol which may be more of a factor than anything else.
Interestingly enough, there are hundreds if not thousands of studies documenting the role of proper diet and exercise in decreasing health risks across the spectrum and thus increasing longer lifespans. At the end of the day, fasting can be a useful spiritual or health practice, but not one geared towards losing weight.
Kevin Richardson is one of New York City’s most sought after personal trainers and the creator of Naturally Intense High Intensity Training 10 Minute Workouts. Get a copy of Kevin’s award winning free weight loss ebook here and v Visit his official website at www.naturallyintense.net.
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