Breastfeeding has long been believed to help mothers get their figure back after giving birth. A new study claims it could also help them stay slim for decades.

Researchers at the Oxford University found that women who breastfed their babies even for a few months after the birth were less likely to be obese 30 years later. They researchers claimed worked out that for every six months a woman gives her baby breast milk, she loses around two pounds, depending on her initial weight and height.

Although this may not sound much, the researchers claimed it could help prevent thousands of deaths from cancer, heart problems and other illnesses related to obesity., the Daily Mail reported. The study, published in the International Journal of Obesity, surveyed 740,600 women whose average age was 57. They had all answered questions about how many children they had and the total number of months they had spent breastfeeding.

Experts have already established that breastfeeding uses up large amounts of energy which is equivalent to burning 500 calories a day — the same as a typical gym session.

Now, the researchers worked out that for every six months a woman breastfeeds her baby, her body mass index (BMI) — the measurement of obesity — falls by 1 per cent.

An average woman who is 5ft 6ins tall and weighs 11st 1lb (70.30kg) would have a BMI measurement of 25, classified as overweight. But if her BMI was to fall by 1 per cent it would be about 24.75, which is deemed “healthy”, and she would weigh 10st 13lb (69.39kg).

Dr Kirsty Bobrow, who led the study, said: “We already know breastfeeding is best for babies, and this study adds to a growing body of evidence that the benefits extend to the mother as well — even 30 years after she’s given birth.

“Pregnant women should be made aware of these benefits to help them make an informed choice about infant feeding.”

The researchers also pointed out that breastfeeding may help prevent thousands of deaths related to obesity from cancer, heart disease and diabetes.

Prof Dame Valerie Beral, Director of Cancer Epidemiology Unit at Oxford University, who was also involved in the study, said: “Our research suggests that just six months of breastfeeding by UK women could reduce their risk of obesity in later life.

“A one per cent reduction in BMI may seem small, but spread across the population of the UK that could mean about 10,000 fewer premature deaths per decade from obesity-related conditions, such as diabetes, heart disease and some cancers.”

The research also found that women were more likely to be obese if they had several children.

This backs up the concerns of health professionals that many gain weight during pregnancy which they don’t lose after the birth of their babies.