Fathers-to-be appear to be influenced by their partners' weight gain
The average father-to-be gains a stone (6.35kg) during his partner's pregnancy, a poll has suggested.
A fifth of 5,000 men surveyed said they were given larger meals, and 41% said there were more snacks in the house.
The poll, for marketing company Onepoll, also found 25% of men ate more food to make their partner feel better about her weight gain.
One fathers' group said dads had to be aware their unhealthy behaviour could influence their partners.
Favourite 'male pregnancy' snacks include pizza, chocolate, crisps, and more inappropriately, beer.
The average weight gain equated to men putting on around at least two inches around their waist, and a quarter were forced to buy a "paternity" wardrobe.
A fifth of fathers-to-be said they had only realised they had put on weight when their existing clothes stopped fitting.
But 19% said it was their friends who had felt they needed to make it clear they were fatter than before - via jokes about having a "bun in the oven".
Forty two per cent of couples spent more time visiting pubs and restaurants for dinner in a bid to make the most of their precious time together before the baby was born.
However, only a third joined their partners on a post-pregnancy diet.
'Women can't be blamed'
A spokesman for Onepoll said: ''The average woman puts on about two and a half stone during her pregnancy, and it's not at all uncommon for her to crave more fatty foods and need more regular snacks.
''In fact, women are encouraged to consume an additional 300 calories a day - through eating healthier snacks - to make sure the nutritional needs of the baby are met.
''So if the kitchen cupboards are suddenly brimming with snacks and food, it's no wonder blokes are tempted to tuck in as well."
But he added: "The only problem seems to be that men are choosing to snack on unhealthier options such as sweets and cakes - and I don't think women can be blamed for their partner's drinking more beer!''
A spokesman for the Fatherhood Institute said: "Research shows that fathers' health behaviour during pregnancy is really important, not just for themselves but because of the impact their behaviour has on the mothers' health behaviour - which can of course affect the baby's health.
"This is relevant not just in terms of eating but also smoking, drinking and substance abuse.
"It's vital that health services address dads as well as mums during this vital time, and continue to do so once the baby is born."