Weight loss is a national obsession. One of the latest fads is “intermittent” fasting or IF.
It’s a simple method. You keep your current high-calorie diet – for 5 days. On another 2, you reduce your food intake drastically – by as much as 75%.
The diet is becoming popular because it doesn’t seem to require too much effort from the dieter.
You don’t have to count calories – or change your eating habits for 5 of the 7 days. There’s no exercise involved, just a modicum of self-restraint. And it doesn’t increase your food budget.
But does it really work?
In one systematic study, intermittent fasters and “normal” daily dieters both lost weight compared to those that didn’t diet at all. But there was no appreciable difference in the benefits of the two diets.
Intermittent fasting may have special appeal to obesity sufferers. In recent clinical trials, some lost 15 pounds relatively quickly. However, the test subjects were all middle-aged women. No studies have been conducted among men, minors or seniors.
Another part of IF’s sales appeal may be its religious overtones. Fasting is thought to engender introspection and a sense of serenity in the practitioner.
In addition, research with animals has shown that regular fasting may reduce the risk of cancer and slow the aging process.
“One hypothesis is that fasting can activate cellular mechanisms that help boost immune function and reduce inflammation associated with chronic disease,” says Dr. Frank Hu, chair of the department of nutrition at the Harvard T.H. Chan School of Public Health.
Critics say it’s all hype. IF’s fasting period is too short. Fasters still eat; they just cut back for two days.
And they don’t necessarily start developing higher consciousness. Many start to feel moody, anxious, irritable and well, hungry. Not everyone can cut it.
Paradoxically, IF may not reduce the practitioner’s overall caloric intake. Some IFers compensate for their 2 days of fasting by binge-eating during their “normal” 5-day eating period, studies show. They may end up eating more, not less.
There are other versions of IF — mainly “alternate-day” fasting, or ADF — that may have greater potential, supporters say.
ADF, unlike IF, requires practitioners to eat no food at all during the fasting period — about 48 hours total, after a 12 hour eating period.
In a study released just last week, ADF practitioners lost an average of 8 pounds over 4 weeks. They also reported reduced cholesterol. These benefits accrued regardless of the dieter’s baseline weight.
But regular fasting also has potential downsides. Recent studies with laboratory mice have shown that it may weaken the immune system, making fasters more susceptible to allergies and disease.
ADF, in particular, may damage the practitioner’s pancreas and increase the risk for type 2 diabetes. Oops.
And fasting can also produce a stress response, resulting in increased levels of cortisol, which can trigger the cravings and binge-eating witnessed in some IF devotees.
Still, the possibility that IF and ADF could yield comparable weight-loss benefits as diets that rely on reduced caloric intake – or a stark change in the types of food consumed — could make them immensely appealing
“Fast and feast” diets do promise to take away a lot of the angst associated with trying to adhere to the DaVinci Code of today’s complex food diets.
Especially for those of modest means, or on a tight budget (who isn’t these days), IF and ADF promise to make dieting not only simple but inexpensive.
But science has yet to determine if the prospective benefits of IF and ADF are as great as their supporters claim, never mind the prospective costs.
Without additional research, “fast and feast” must be ranked as a “fad.” But some fads have a way of enduring.
Throw in a little yoga or another healthy distraction during the fasting period, and IF and ADF could well be here to stay.