Study says this is because of dietary imbalance of protein that affects quality of DNA that is being passed down from father to child.
A new research now suggests that men who don't eat enough protein have poor sperm and are more likely to have children who will face a lifetime of obesity.
According to a story published in MailOnline, mice fed diets containing half the recommended amount of protein had lower quality sperm and seminal fluid – which carries swimmers.
The study found that their offspring were fatter and had signs of type 2 diabetes when they were the human equivalent of 30 years old.
According to researchers this because a dietary imbalance of protein that affects the quality of DNA that is being passed down from the father to the child.
However, the Nottingham University team remain unsure as to how a lack of the nutrient, found in meat and lentils, can weaken sperm.
While studies have shown that sperm from men who are overweight, smoke or drink excessively are of poorer quality, little trials have delved into the impact of such lifestyle factors on the long-term health of a father's children.
The new study, on the other hand shines light on that gap – by examining the offspring of mice when they were 30.
The study, lead by Dr Adam Watkins fed male mice a diet with 18 per cent or nine per cent protein.
Sperm samples were collected from the dead male mice, so scientists could analyse the difference between the two groups.
The group found that mice who were put the diet lacking a sufficient amount of protein produced poorer sperm.
Researchers used the sperm collected from the dead male mice to impregnate female mice, who had all been given a normal diet.
The health of their offspring was then analysed when they turned four months old - the equivalent of around 30 in humans and scientists found they were fatter that their counterparts.
The study was published in the Proceedings of the National Academy of Sciences.
The study further found that they showed signs of type 2 diabetes and had slower metabolisms.