Eating a big breakfast, heavy in carbs, is the key to keeping slim, according to new research.

A new study found that women who eat half of their daily calories first thing in the morning lose more weight in the long term than those who start the day with a small breakfast.

And they are also less likely to pile the pounds back on.

Dr. Daniela Jakubowicz, from the Hospital de Clinicas in Caracas, Venezuela, who led the study, said: "A very low carbohydrate diet exacerbates the craving for carbohydrates and slows metabolism. After a short period of weight loss, there is a quick return to obesity."

It is thought that eating a meal packed with protein and carbohydrates helps cut cravings for sweet or starchy foods, and boosts the metabolism.

Scientists compared the "big breakfast" diet with a strict low-carb weight-loss regime.

Jakubowicz and a team at Virginia Commonwealth University studied 94 obese, inactive women and found that low-carb dieters initially lost more weight.

The strict low-carb diet caused an average weight loss of 28 pounds; the big-breakfast version cut 23 pounds.

However, after eight months, the strict dieters had regained 18 pounds. The big-breakfast eaters continued to drop weight, losing another 16.5 pounds.

Those on the big breakfast diet lost more than 21 percent of their body weight, compared with just 4.5 percent for the low-carb group.

Women who ate a big breakfast reported feeling less hungry, especially before lunch and had fewer cravings for carbs than the other women did. The big breakfast dieters ate an average of 1,240 calories per day, 610 of which were consumed at breakfast. The low-carb dieters ate just 1,085 calories per day.

The findings will be presented this week at ENDO 08, the 90th annual meeting of The Endocrine Society in San Francisco.