Drinking 'diet' soft drinks in an effort to cut calories may be counter productive, according to Professor Helen Hazuda from the University of Texas Health Science Center.

The study found that out of 474 men and women who drank soft drinks had an average of 70% increased waist measurement, compared with those who drank none.

Those who drank two or more diet drinks daily had on average a 500% increase in waist circumference compared with those who drank none.

Abdominal fat is a major risk factor for diabetes, heart disease, cancer and other chronic health conditions.

'They may be free of calories, but not of serious consequences'