Fasting & the French "absence of excess"

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Fasting is garnering attention lately as both a weight-loss method and health-promoting strategy.  Granted, calorie-cutting has been considered the gold standard for weight loss for decades. Then we realized it could slow one's metabolism, lead to overeating, or was just plain difficult to sustain. Drastic calorie cutting was better in theory than practice.

Cut to 2013, and the role of caloric reduction is being examined anew, with "fasting" being the subject of much research. And more specifically, research is looking at how fasting on an intermittent basis might offer the same benefits as fasting on a continual basis, thus making intermittent fasting more convenient and tolerable.

 

 

 

Several terms used in medical literature to describe various forms of fasting are:

  • Energy restriction (ER)
  • Continuous energy restriction (CER)
  • Intermittent energy restriction (IER)
  • Intermittent fasting (IF)
  • Dietary energy restriction (DER)

The differences amongst them pertain to the duration and extent of the food restriction. There is research supporting the idea that some forms of caloric restriction have health benefits, but it's not overwhelmingly conclusive at this point. Below are some findings from the scientific literature.

One paper asks if fasting is "the ultimate diet" and didn't present any strong conclusions, but it did raise the important question, "what impact does fasting have on psychology?" noting:

How a subject feels during weight loss is very important, because this will be an indicator whether they will be compliant to the regime. If a subject does not feel well physically or mentally, then they will learn to avoid the behaviour that makes them feel unwell. The psychological response to a diet is therefore very important in terms of the subject's feelings of well-being, quality of life, libido, energy or fatigue levels, anxiety or depression. If dieting per se can improve these parameters, then this can add to the feeling of success and motivation to maintain the regime to lose weight.

Another study looked at young, overweight women, examining weight loss and disease risk markers. This study divided the women into two groups: The first group -- "intermittent energy restriction" subjects -- reduced caloric intake by 25% (down to about 650 calories) for 2 days each week.  The second group -- "continuous energy restriction" subjects -- reduced their caloric intake to about 1500 calories every day of the week. This study showed that IER is as effective as CER for weight loss and reducing disease risk, meaning that people don't have to reduce caloric intake every day of the week to benefit from caloric restriction, but can instead partake in reductions only two days per week, albeit with those days' reductions being more drastic in nature.

This premise -- that one need only reduce calories on an intermittent basis, not every day -- is one being touted by current popular diet books.  One of several such diets, "The Fast Diet," was recently described in The New York Times as being akin to something called the "5:2 diet" -- 5 days of eating what you want, and 2 days of fasting -- meaning very low caloric intake (500 calories for women, 600 for men), not total abstinence from food.

Getting back to the research, another study on the impact of caloric intake upon health outlines the following:

The impact of dietary factors on health and longevity is increasingly appreciated. The most prominent dietary factor that affects the risk of many different chronic diseases is energy intake -- excessive calorie intake increases the risk. Reducing energy intake by controlled caloric restriction or intermittent fasting increases lifespan and protects various tissues against disease, in part, by hormesis mechanisms that increase cellular stress resistance.

Among dietary factors, the amount of calories consumed has been unequivocally and causally associated with the risk of many prominent age-related diseases. Put simply, high-energy intake increases, while low energy intake decreases, the risks of cardiovascular disease, type 2 diabetes, stroke, cancers and possibly neurodegenerative disorders.

Animal models showed protective effects of dietary energy restriction against  cancers, mammary tumors, prostate cancer, myocardial infarction and stroke, and other animal studies showed results including increased resistance to neurotoxins in models relevant to epilepsy, Huntington's disease, Parkinson's disease and Alzheimer's disease.

This is an emerging area of research and animal studies shouldn't be taken as evidence that such findings would be replicated in human studies. The paper did, however, note that:

Studies of humans also suggest that dietary energy restriction can counteract disease processes. For example, alternate day fasting improved symptoms and reduced markers of inflammation and oxidative stress in asthma subjects.

It is an intriguing concept -- that caloric restriction can offer some health benefits, whether by protecting us against the harmful effects of overeating, or via hormesis (which is the body's adaptive response to intermittent stress), or perhaps by some other mechanism. There are many details left to sort out, however, and a very important -- potentially complicating -- factor should be noted, and that is the potential for this supposed health-improving measure to lead to an eating disorder or other harmful health outcome. For example, one paper examines the relationship between caloric restriction, stress and binge eating, with study results suggesting:

Stress associated with moderate caloric restriction promotes long-term alterations in genes critical in feeding and reward circuitry that influence food intake and stress-related behaviors. Such epigenetic mechanisms likely hold an evolutionary advantage in times of famine, but in our current environment of high caloric availability would function against our health and contribute to difficulty in weight management. It seems appropriate that the brain developed strategies to guard against loss of calories by increasing the likelihood that a previous restriction experience would promote future behaviors to increase consumption of calorically dense foods.

As one final point regarding fasting and health, I wonder if part of what contributes to France's healthy lifestyle is their belief in moderation and avoidance of overeating.  In a paper outlining differences between French and American attitudes toward food, it was noted that:

Absence of excess, related to both abundance and quantity, is a long-standing theme in French eating. French food is generally considered to be elegant, sophisticated, and graceful.

Theorists wrote that gastronomy was about discrimination and moderation, with quality being more important than quantity. While daily French food is far from elegant, the influence of gastronomes in France impacted the manner in which the French regularly eat and inspired the value of moderation.

The impact of caloric intake upon health is an interesting area of research, with different theories as to how and whether caloric restriction should be implemented.

  • Stress and psychological impact are two important factors to consider, however, as the negative psychological impacts of fasting could offset the purported benefits.
  • This research area also raises question about the notion of quantity vs. quality, and whether we're better off eating any food in moderation, versus overeating healthier foods.
  • Regardless of what the verdict on fasting ends up being, the notion of "absence of excess" -- of at least not overeating -- is an excellent ideal to embrace.