Obese and diabetic men are more likely to have overweight daughters, according to University of South Wales study. Researchers said that the paternal diet, body weight and health affect the baby's genes and health. The effect is more prominent in girls.

This is the first study to have documented the effects of father's health and nutrition on children's risk of obesity.

For the study, researchers conducted the experiment on male lab rats - one group was obese, diabetic and on a high-fat diet, while the other group weighed normal, was not diabetic and had a normal diet. The two groups of rats mated with healthy, thin female rats.

They found that rats, born from the unhealthy fathers, had altered gene expressions in the fat and pancreas tissues, the two important metabolic tissues. This altered gene expression could lead to obesity and premature ageing in future. Other affected genes included indicators of cancer and chronic degenerative disease.

These offsprings found it difficult to break down glucose, even when they were on a healthy diet. Plus, the obese rats displayed gene function changes in pancreatic islets, which are responsible for generating insulin to control blood glucose and the fat tissue.

"The fact that similar gene markers were affected in pancreas and fat tissue tells us that some of the same pathways are being influenced, possibly from the earliest stages of life," Dr Margaret Morris, a researcher for the Pharmacology School of Medical Sciences, said in a press release.

Morris said that further studies are necessary to identify ways to reduce the impact of poor paternal metabolic health on offspring.

The study has been published in the FASEB Journal.

"For a long time, we've known that the nutrition and health status of women who are pregnant or who want to get pregnant is critical to the health of her offspring, and we've also suspected that the same is true for fathers to a lesser degree," Gerald Weissmann, editor of The Federation of American Societies for Experimental Biology Journal (FASEB), said.