London, April 19 (IANS) Going on a diet could increase the risk of developing potentially deadly conditions such as heart disease, diabetes and cancer, a study has found.

The study revealed that those who controlled their calorie intake produced higher levels of the harmful stress hormone cortisol and exposure to the hormone actually made some dieters put on weight, reports dailymail.co.uk.

Dieting could actually damage mental health too as many suffered increased psychological stress when they were constantly forced to count calories and monitor what they ate.

"Regardless of their success or failure (in losing weight), if future studies show that dieting increases stress and cortisol, doctors may need to rethink recommending it to their patients to improve health," the researchers said.

"Chronic stress, in addition to promoting weight gain, has been linked with coronary heart disease, high blood pressure, diabetes and cancer. Dieting might potentially add to this stress burden and its consequences would best not be ignored," they added.

The study, by California University in San Francisco and Minnesota University, looked at 121 women who were put on a standard three-week diet of 1,200 calories a day - around half a woman's recommended daily amount of 2,000 calories.

Each patient was asked to provide a saliva sample before and after the study to test for cortisol levels. The results showed a significant increase in the amount of the hormone after three weeks on the programme.