Weight Loss: No Fast Magic

Don’t be distracted by quick-fix promises to help you slim down

woman weighing herself

I have long been struck by the jarring contrast in how responsible adults approach the management of their pounds and their dollars. We all know that get-rich-quick schemes are the stuff of diverting and fundamentally silly sitcoms, like The Honeymooners. Ralph Cramden was a loveable doofus because he represented the naïve triumph of hope over experience, week after week. As his long-suffering wife, Alice, looked on, and his long-suffering friend, Ed Norton, was dragged along, Ralph signed up again and again for just such schemes. Of course, he never got rich—and always returned to driving his bus.

Reasonable adults view these episodes just as intended: as comedy. But the same population of reasonable adults, when enticed by lose-weight-fast or get-healthy-quick promises, goes into some bizarre trance and starts reaching for their credit cards.

The result is predictable: It is, and long has been, a seller’s market for almost every weight loss promise imaginable. Perhaps just as familiarity breeds contempt, desperation breeds gullibility.

Slowing Support for Intermittent Fasting

Among the more recent entries in this parade is the implied advantage of intermittent fasting. The arguments for this dietary approach insinuate, when they don’t actually claim, some kind of quick-fix magic independent of the obvious: One tends to eat less overall when only eating some of the time. That self-evident aspect of intermittent fasting lacks sex appeal, so the claims go off in other directions: It’s about revving your metabolism, or purging your system, or burning fat instead of carbohydrate or…whatever.

It doesn’t matter, because none of it’s true. That’s what two recent studies of intermittent fasting suggest.

The first, a study in Science Translational Medicine, compared intermittent fasting for three months to usual diet. The study did show metabolic benefits from fasting, but that’s because eating some days rather than all days produced weight loss. All of the metabolic benefit demonstrated appeared to be attributable to weight loss.

So really, that study raised a question rather than answered one: What happens when people lose weight by fasting occasionally versus limiting calories every day? Is there some unique benefit to the intermittent fast?

Enter the second study, published in JAMA Internal Medicine. This trial compared weight loss and metabolic risk measures in 100 obese adults randomized to intermittent fasting, daily calorie restriction, or a control group. Both approaches to calorie reduction produced weight loss and most of the same metabolic improvements relative to no intervention—but they did not differ at all from one another. In other words, the metabolic benefits of fasting are the benefits of weight loss, which in turn result from limiting the total amount eaten over any given period of time.

Empty Promises

There was, however, one noteworthy difference between fasting and daily calorie restriction: the dropout rate. It was highest for the fasting group, which lost 38 percent of those initially assigned to it, as compared to 29 percent and 26 percent for the calorie restriction and non-intervention groups, respectively.

I am not suggesting that fasting is necessarily a bad idea. Intermittent fasting was almost certainly part of the native, Stone Age human experience, but not by choice; our ancestors went without eating whenever circumstance conspired against them finding and acquiring food. It makes sense that we are reasonably well-adapted to tolerate periods of relative famine.

Fasting figures in many, if not most, religious practices as well. In that context, it serves—or is intended to serve—as a platform for concentration, renewal, reflection, and spiritual nourishment. Any benefits to weight or physical health are rather incidental.

Claims of quick-fix magic, however, are unsubstantiated by science and simply the latest flavor of pop-culture weight loss nonsense. They seem to me dangerous in a number of ways. They may goad some inclined to lose weight in other ways into believing that this is the one, best approach. They may foster eating disorders by encouraging binges after periods of deprivation. They may cause direct harm to those who tend to need stable and frequent dietary intake, notably those prone to hypoglycemia, or taking insulin to manage diabetes. And they tend to be rather inattentive to the idea that the “best” diets for weight and health tend to be those you can share with your household, align with your routine and lifestyle, and practice for a lifetime.

That intermittent fasting could satisfy these criteria for some is perfectly plausible. That it represents a revelation for all or offers some magical approach to weight loss is neither.

The Secret to Weight Loss Isn’t a Secret

Personally, I think the best approach to controlling total calories consumed over time is to eat a diet of truly wholesome foods in any genuinely sensible combination. One of the many virtues of whole, wholesome foods and diets of mostly plants is that they fill us up on fewer calories. The very diets that most reliably foster lasting control of weight foster overall good health as well. Such an approach is about living, not dieting; about a lifetime, not the short term; and about your whole family, not you alone. Intermittent fasting is not precluded from such approaches, but it certainly is not required.

Fasting delivers no fast magic for weight loss. If you hear claims to the contrary, step away from your credit card and nobody will get hurt! If losing weight and finding health are of interest, you certainly can get there from here with the reliably tried and true approach of eating good foods and being routinely active—neither magic, nor Ralph’s bus required.

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