It is indeed yet another theory on how we can lose weight more effectively. Whilst crash diets have been thought to be the unhealthy way to lose weight, Dr Susan Roberts a British scientist currently working as a professor of nutrition at Tufts University in Boston, Massachusetts, and author of The Instinct Diet says that low-calorie diets can be healthy if you do them right, and can work wonders on pounds and inches in just a few weeks.

Clinical experience shows that somebody with a serious commitment to weight loss can lose up to 20 pounds - and two to three dress sizes - in two months. That's a lot of weight, and an enormous change in appearance for most of us.

Best of all, if a crash diet is done right (and you make permanent changes to how you eat) it can yield results that will stand the test of time just as well as those slow and careful, long-term diets that emphasise depressingly incremental drops in weight.

Conventional wisdom says that rapid weight loss leads to rapid weight regain, but a new generation of science is showing that slow isn't necessarily better.

In fact, fast weight loss - if achieved with a healthy, caloriecutting food-based diet - can bring long-term success equivalent to the more gradual weight-loss programmes, which is reason for procrastinators everywhere to rejoice. In fact, for some people, healthy crash dieting may work even better than a diet that lasts all year.

A recent study from my laboratory at Tufts University in Boston, Massachusetts, found that the slow and careful approach seems to be sustainable only by those dieters who are not sidetracked by rich food, party snacks and other common food challenges in daily life.

So where does exercise come in?

My laboratory summarised 36 years of published studies on exercise and weight, conducted between 1969 and 2005, and found that adding even an hour of exercise per day results in an average fat loss of just six pounds over the course of several months - hardly the benefit one would expect from all that work.

Shedding pounds: Studies show that exercise is not the key factor in weight loss

Might we stop to wonder if we're not losing weight due to the foods we consume? Or should we keep blaming the lack of time and exercise for our weight gain as we age?

Perhaps a crash diet of healthier foods might help.

Read on here.