The new guru? Dr Mike Moreno says dieters can expect weight-loss of 10-12lb in just 17 days on his plan

Losing a dress size in little over two weeks may sound too good to be true – but that’s exactly what Dr Mike Moreno is promising in his new book.

The 17 Day Diet, which has been taking the U.S. by storm, promises weight-loss of 10 to 12lbs in just two to three weeks.

Dr Moreno, who runs a family practice in San Diego, also insists, unlike many fad diets, that the results are sustainable.

His programme is organised into four cycles consisting of 17 days each and allows dieters to vary carbs, proteins and fruits to stimulate metabolism and improve digestion.

He told Good Morning America that he chose 17-day periods as a means of keeping the body’s metabolism as high as possible.

He said: ‘That’s right before the time when the body starts to recognise the diet as a habit and metabolism starts to slow as a result.’

He added that the diet plan promotes what he calls ‘clean’ eating, which includes avoiding sugars and processed foods.

The book also instructs dieters to eliminate alcoholic beverages during the initial stages.

Instead, the focus is on how to make healthy lifestyle choices, such as eating breakfast each morning, drinking more water and increasing intake of ‘natural’, or unprocessed, foods.

Rachel Wilcox, a mother of three, told GMA how she had tried countless diets – including the low-carb Atkins plan –