With the holiday season just around the corner, here's news which will be welcomed by those who've been meaning to lose weight but haven't got around to it.
Crash dieting is an effective way to slim, scientists have found. Despite health warnings from nutritionists, research showed that dieters who shed the most weight in their first month also lost more in the long run.
And they were just as likely to maintain their new shape as dieters who lost less.
The message, says the study, is that the first few weeks of a diet are critical and may spur dieters on.
University of Florida researchers followed more than 250 obese women who were asked to cut their calorie intake and increase their exercise for 18 months. Those who lost more than 1.5lb a week during the first month lost more than two stone within six months on average.
But those who initially lost less than half a pound a week ended up losing just 11lb overall. The 1.5lb a week figure is well within the safe limits recommended by most dieticians.
Although women in both groups did put some weight back on, those in the speedy group fared no worse than the others.
Writing in the International Journal of Behavioral Medicine, the researchers said: 'Because weight regain reverses the health benefits achieved with weight loss, considerable efforts have been placed on identifying behavioral factors that may be associated with long-term success. Studies have shown that rate of initial weight loss, even within the first few weeks of treatment, may serve as an important predictor of long-term success.
'Our findings indicated fast weight losers obtained greater weight reduction and were not more susceptible to weight regain than long-term losers.'
For the first six months, the dieters attended group meetings each week. After that, they had to make do with a mixture of fortnightly phone calls, newsletters and group sessions.
In the past, nutritionists have insisted that fast dieting leads to deficiencies of vital minerals and nutrients.
If potassium and sodium levels drop far enough, the dieter can have a heart attack. If energy levels fall, the body can start to burn muscle, harming the liver, kidneys and brain.
Other research has shown that the secret to losing weight and keeping it off lies in walking a marathon distance a week.
A study of thousands who had shed two stone found walking helped them keep the weight off.
The dieters exercised for 60 to 90 minutes a day, walking the equivalent of 26 miles a week.