The widely held belief that we’re less likely to regain weight when we lose it gradually rather than quickly is not true, according to an Australian study published last week. The study found that keeping off the pounds over the long haul is difficult regardless of how quickly the weight is initially lost, although people are more likely to achieve their target weight — and to do so more rapidly — when calories are severely restricted.
The research, published in medical journal The Lancet Diabetes and Endocrinology, contradicts international guidelines which recommend losing weight gradually in order to keep it off for good.
Nutrition experts have long warned of the dangers of crash diets as they lack a broad range of nutrients essential for health.
During the study, 200 obese adults followed either a 12-week rapid weight loss plan or a 36-week gradual programme.
Those on the rapid loss scheme ate only a food substitute of between 450 and 800 calories each day. The gradual dieters had their calorie intake reduced by 500 calories a day from the recommended 2 500 for men and 2 000 for women.
Participants who lost more than 12.5 percent of their body weight were then put on a three-year weight maintenance diet.
Four out of five crash dieters reached their target weight, compared with just half of those dieting more slowly.
And the crash dieters were no more likely to put the weight back on. In fact both groups regained around 71 percent of what they had lost within three years.
Katrina Purcell, dietician and study author, said: “Guidelines recommend gradual weight loss for the treatment of obesity, reflecting the widely held belief that fast weight loss is more quickly regained. However, our results show achieving a weight loss target of 12.5 percent is more likely, and drop-out is lower, if losing weight is done quickly.”
The study was led by Professor Joseph Proietto of the University of Melbourne in Australia. The researchers claimed the crash dieters were more successful because rapid weight loss gave them more incentive to keep going. Eating food substitutes was also easier than simply reducing calories.
However they warned it was “impossible” for crash dieters to get all the nutrients they needed and said they also had to take medically approved supplements. Other experts were cautious about the findings. They pointed out that fad crash diets such as the cabbage soup or juice diets could be dangerous.
Professor Naveed Sattar of the University of Glasgow also expressed concern at the findings.
He said even the study’s gradual dieters lost weight too quickly in his view. “One must remember that weight gain in many who are obese has occurred over years and reversal may need to be relatively slow so that the brain and systems that regulate appetite have time to reset,” he said.
The study, which started in 2008, used Nestle’s Optifast as the food substitute for the crash dieting group. Professor Proietto was chairman of the firm’s Optifast medical advisory committee from 2005 to 2010. However, the research was not commercially sponsored.