Pudgy older fathers live longer, are more attractive to the opposite sex and are better at passing on their genes than their leaner counterparts, scientists have claimed.
Becoming fatter after fatherhood due to decreasing testosterone levels may not fit the "macho" ideal, but it actually prolongs lives and strengthens immune systems, according to Richard Bribiescas, professor of anthropology and deputy provost at Yale University.
There is evidence that these men are less likely to suffer from heart attacks and prostate cancer, while a study in 2008 found that men with high metabolisms were around 50 per cent more likely to die in a given year than those whose bodies burned up less energy at rest.
"Macho makes you sick," said Prof Bribiescas. "The Hollywood image of the swaggering, dashing man dispatching bad guys and carrying the day conjures up a perception of indestructibility.
"While men are on average larger and physically stronger than women, men have a considerable weakness.
"We have a harder time fighting off infections and illness compared with women, and... men simply do not take care of themselves.
"This has a significant negative impact on the pace at which men age."
Professor Bribiescas also argues that becoming more podgy makes dads more likely to invest their time in their children rather than looking for other women, while the increased levels of fat could make them more attractive to women.
Among those to father children later in life are Robert De Niro, who had a child at 68, and Rod Stewart, who was 66 when his eighth child was born.
"[One] effect of lower testosterone levels is loss of muscle mass and increases in fat mass," Prof Bribiescas writes in his book How Men Age: What Evolution Reveals About Male Health and Mortality.
"This change in body composition not only causes men to shop for more comfortable trousers but also facilitates increased survivorship and, hypothetically, a hormonal milieu that would more effectively promote and support paternal investment."
The research follows the "dad bod" trend, in which middle-aged men were praised for their doughy physiques.
However, a Cambridge University study last year found that women searching for a father for their children should choose long-distance runners, who traditionally have very low levels of fat, because they are more likely to have stronger sex drives and higher sperm counts.