Health Benefits Of Fasting?

sharma-obesity-fat-dietingEven a cursory glance at popular media stories on diets and weight loss will lead you to countless posts on the supposed benefits of alternative-day, intermittent or other forms of fasting.

But just how much evidence is there that any of this is actually beneficial to your health (i.e. if you are not a mouse).

This question was addressed by Benjamin Horne and colleagues from Salt Lake City, Utah, in a paper published in the American Journal of Clinical Nutrition.

The researchers review the evidence on various forms of fasting from the published literature, which consists of a grand total of three randomised controlled trials, together involving about 100 participants, with durations ranging between 2 days to 12 weeks.

Although all three trials reported some benefits in terms of body weight, cholesterol and other surrogate markers, the authors failed to find any study that looked at actual clinical endpoints (e.g., diabetes or coronary artery disease].

To be fair the authors did find two observational studies in humans (both involving the first author of this study), where fasting was associated with a lower prevalence of heart disease or diabetes but, as readers should be well aware, these types of studies cannot prove causality.

I guess it would be fair to say that the popular enthusiasm about the health benefits of various forms of fasting, as far as their benefits for humans are considered, appear largely based on hope and hype – at least as far as clinically meaningful outcomes are concerned.

This is not to say that fasting, whether alternative day or otherwise, may not well have some medical benefits – fact is, we just don’t know.

Or rather, as the authors put it,

“whether fasting actually causes improvements in metabolic health, cognitive performance, and cardiovascular outcomes over the long term; how much fasting is actually beneficial; and where the threshold of hormesis resides (i.e., a balance between long-term benefit from fasting compared with harm from insufficient caloric intake) remain open questions….considerable additional clinical research of fasting is required before contemplating changes to dietary guidelines or practice.”

Vancouver, BC