Shedding pounds too rapidly has long been considered by experts as a recipe for short-lived success, almost inevitably leading to reoccurring weight gain, a phenomenon also known as yo-yo dieting. A better approach, so the prevailing thinking went, was to limit the desired weight loss to one to two pounds a week, enough time to let the body adjust and make the changes permanent.
But the idea that slimming down at a reduced rate produces better outcomes long-term may be delusional, according to a new study that found no significant differences for participants in so-called crash diets by comparison to their counterparts who took a slower pace. Eventually, almost all gained much of their original weight back, and in some cases added more.
For the study, which was recently published in the journal The Lancet Diabetes & Endocrinology, researchers from the University of Melbourne, Australia, divided 200 obese adults randomly in two groups and submitted them to either a 12-week rapid weight loss (RWL) regimen on a very low-calorie diet, or a 36-week gradual weight loss (GWL) program that required a daily calorie reduction of no more than 500 calories per day.
As expected, the dieters who took the fast approach showed greater initial successes, but surprisingly, they did not regain weight faster than those who went about their weight loss more slowly. After only three years, weight regain was about the same in both groups.
Based on these findings, the authors of the study report concluded that current dietary guidelines recommending gradual over rapid weight loss may be unsupported if considered for lasting results.
This, of course, is an important caveat. Naturally, lasting results are important for any weight loss endeavor. It is no secret that keeping unwanted pounds off for good is the hardest part of any diet, no matter what method is chosen.
But there are other considerations as well. Radical crash diets that prescribe severe calorie restrictions and even exclude entire food groups can imbalance a person's metabolism -- the rate at which the body turns food into energy -- thereby preventing important nutrients and vitamins from getting to where they are needed.
Moreover, rapid weight loss affects not just unwanted fat but also lean muscle mass, which is not desirable. When calorie intake is suddenly and substantially diminished, the body uses energy stored in the liver and muscles. Most of the initial weight reduction comes from loss of water and muscle. In other words, people may lose weight, but not in a way that is healthy.
Still, some experts now say that different approaches to weight loss may be suitable for different individuals. In cases of severe obesity, more drastic measures might be called for, at least initially.
"Doctors should, on the base of this study, feel they can suggest a very low calorie diet to obese patients, if they feel that would suit them," said Dr. Susan Jedd, a professor of public health at Oxford University, in an interview addressing the study results with the British newspaper The Guardian. "Even if they put it all back on, they will have been at a healthier weight for some time, which can only be good," she added.
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