The Science Behind Intermittent Fasting | Nutrition Specialist

Though the truth has a tendency to get distorted by time, diet and exercise tendencies have origins in science. Benefits are exaggerated. Hazards are downplayed. Meanwhile science takes a back seat to marketing.

An individual need not look any farther than the emerging tendency of intermittent fasting for a prime illustration. Advocates for taking breaks from eating, for up to 24 hours a week, tout it as a safe and effective method for improving health and wellness. That message has been reaching more and more ears as of late.

"Right now, we are in a vital juncture for fasting," states Brad Pilon, an expert on occasional fasting and author of the novel Eat Stop Eat. "It's becoming extremely popular."

Intermittent Fasting: Know the Facts

Such may become so popular, in fact, that it's moving into trend territory, indicates Pilon. And if something becomes a fad, only for a short period although intensely popular, several problems normally ensue. For one, he states, nutrition experts and many doctors have a tendency toward dismissing fads from hand. So clients and their patients, while shielded from the claims of dieting evangelists that are overzealous, can lose out on the advantages of fasting right.

Yet another concern is that promoters of intermittent fasting will, perhaps unintentionally, encourage extreme behaviour, such as bingeing. This is reflected in the photos accompanying many recent new articles on "the fast diet" or even the "5:2 diet." Often, they portray people eating loads of high-calorie, high-fat foods, like hamburgers, french fries and cake. The implication being that if you fast two days a week, you are able to consume a lot during the remaining five days.

Not so, say more moderate proponents of fasting. Their take on intermittent fasting: eat sensibly the majority of the time, eat nothing for a protracted period every now and then, gratify only on occasion (maybe once a week, state, on a predetermined "cheat day"). There is study, they assert, to back up the health benefits of wisely.

There is indeed a large body of research to support the health benefits of fasting, although most of it has been conducted on animals, not humans. Still, the results have been promising. Fasting has been shown to improve biomarkers of illness, decrease stress and preserve memory and learning function, based on Mark Mattson, senior investigator at the National Institute on Aging, part of the US National Institutes of Health. Mattson has investigated the health advantages of intermittent fasting on the cardiovascular system and brain in rodents, also has known for "well-controlled human studies" in people "across a assortment of body mass indexes" (J Nutr Biochem 2005;16:129--37).

There are several theories about why fasting offers physiological advantages, says Mattson. "The one which we have researched a great deal, and designed experiments to examine, is the hypothesis that during the fasting period, cells are under a mild strain," he states. "And they respond to the stress adaptively by enhancing their ability to deal with additional stressors and, possibly, to resist illness."

Although the term "stress" is frequently used in a negative sense, taxing the body and mind has benefits. Consider exercise, which stresses, in particular, muscles and the cardiovascular system. So long as you give the body time to recover, it will grow stronger. "There is considerable similarity between how cells react to the pressure of exercise and how cells react to intermittent fasting," says Mattson.

Additional Research: Intermittent Fasting

Mattson has contributed to several additional research on intermittent fasting and caloric restriction. In one, obese adults with moderate asthma consumed only 20% of their normal calorie intake on alternative days (Free Radical Bio Med 2007;42:665--74). Participants that stuck to the diet lost 8 percent of their initial body weight over eight months. They also found a decrease in markers of oxidative stress and inflammation, and improvement of several indicators and asthma-related symptoms.

In another study, Mattson and colleagues researched the effects of intermittent and continuous energy limitation on weight loss and various biomarkers (such as conditions such as breast cancer, diabetes and cardiovascular disease) among young obese woman (Int rheumatoid arthritis 2011;35:714--27). They discovered for improving weight loss, insulin sensitivity and other wellness biomarkers that restriction was as effective as continuous restriction.

Mattson has also investigated the protective benefits of fasting to neurons. Should youn't eat for 10 - 16 hours, then your body will go for energy, and fatty acids called ketones will probably be released into the bloodstream. It has been demonstrated to protect memory and learning says disease processes in the mind, as well as Mattson.

But maybe it isn't so much that the fasting that creates health benefits, per se, because the consequent overall reduction in calorie intake (if, in other words, you don't overeat on nonfasting days, which could cause a caloric surplus rather than a deficit). That seems, at least, to be true in slowing diseases like cancer in mice, according to Dr. Stephen Freedland, associate professor of urology and pathology at the Duke University Medical Center in Durham, North Carolina.

"Caloric restriction, undernutrition without malnutrition, is the only experimental approach consistently shown to prolong survival in animal models," Freedland and colleagues stated in a study on the effects of intermittent fasting on prostate cancer growth in mice (Prostate Cancer Prostatic Dis 2010; 13:350--5). From the study, mice fasted twice weekly for 24 hours, but were otherwise permitted to eat at liberty. During days, the mice overate. They did not lose weight. Intermittent fasting using compensatory overeating "did not enhance mouse success nor did it delay prostrate tumor growth," the study concluded.

To improve health, the aim should be to shed weight by reducing the entire amount of calories consumed, indicates Freedland, rather than focusing on if those calories are consumed. "If you [do not] eat two days every week, and restrict what you eat another five days, you will lose weight. It is one approach to losing weight," he says. "I am not sure it works any better than trimming down marginally seven days each week."

People should also be skeptical of books written for wide audiences that describe the science behind fasting or another health trend, '' he says. One purpose of writing a novel for the consumer market, after all, would be to sell as many copies as you can. Authors tend to present evidence, while ignoring the facts and their impact. "It has a whole lot of spin when you compose a book."

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By Dr. Alex Jimenez