Weight watchers in the US have discovered a novel way to diet - by eating pork scratchings.

The fad has helped make scratchings, or pork rinds as Americans call them, the country's fastest growing snack with sales up 18 per cent last year.

One weight-loss guru even recommends that the deep-fried pigskin can be dipped in sour cream as part of his controlled diet.

The idea behind it is that cutting out carbohydrates lowers blood sugar levels, thus triggering insulin production which burns fat for fuel.

So pasta and bread have been binned in favour of weight-loss diets that include eggs, butter and bacon, reports the LA Times.

Nutritionists are warning that an all-fat diet can lead to heart and kidney disease, but it isn't stopping the US sales of pork scratchings - which topped $420 million (£280 million) in 1999