Scientists reveal the best and most effective way to lose weight is to go on a crash diet. Despite, nutritionists warning against it, research indicates that dieters who lost the most weight in their first month of trying, also lost the most in the long-term.

Not only did they lose the most weight, they were also more likely to retain their new shape, compared to dieters who lost less.

The message the study delivers is that the first few weeks of a diet are critical, which may spur dieters to persevere.

The researchers from the University of Florida monitored over 250 obese women asked to reduce their calorie intake, including increasing their exercise for 18 months. Those who lost more than 1.5-lb a week during the first month, on average lost over two stone within six months.

However, those who initially lost less than half a pound a week, ended up losing just 11-lb overall. The 1.5-lb a week falls well within the safe limits recommended by most dieticians.

The researchers writing in the International Journal of Behavioural Medicine say, since weight regain reverses health benefits of weight loss, they have worked to identify behavioural factors associated with long-term success.

According to their findings, fast weight losers ended up losing more weight and were not more susceptible to weight regain than long-term losers.'

In the past, nutritionists have insisted fast dieting leads to deficiencies of vital minerals and nutrients. If, potassium and sodium levels drop far enough, it can result in the dieter having a heart attack. And if, energy levels fall, the body can being burning muscle, harming the liver, kidneys and brain.

Other research has shown walking a marathon distance a week, helps lose weight and keep it off too.

A study of thousands who had lost two stone found walking helped keep off the weight.

The dieters exercised for 60 to 90 minutes a day, walking the equivalent of 26 miles a week. As soon as they decreased their physical activity or increased their fat intake, they began regaining weight. For losing weight and keeping it off, one has to make certain lifestyle changes.