A lack of time to exercise, an increase in the number of takeaways and endless sleepless nights are to blame, with six out of ten dads admitting they're 'out of shape'.
Paul Keenan, of Benenden Healthcare, which carried out the Men's Health Forum study said: ''The modern lifestyle is a hectic one and this study clearly shows the impact this is having on fatherhood.
''As we approach Father's Day, we discover that the modern dad's health is suffering under the strain from diverging pressures such as work and family life.
''As a result, dads are taking shortcuts with their diets - leading to increased weight, a more sedentary lifestyle and eventually running the risk of health scares.
''Men's Health Week 2012 is highlighting the fact that heart disease is the biggest killer of men in the UK, and these results show how men are hurtling towards increasing strain on the heart.''
The study of 2,000 fathers found that the average dad can expect to put on 1.6 stone (10.43 kg) after becoming a dad but four out of 10 dads aren't able to pull their (extra) weight in the family home because they're too exhausted.
Fast-paced work lives have led a tenth to have to 'gear themselves up' in order to re-join a hectic family life at the end of the day and more than a quarter sneak in naps during the weekdays in order to cope. One in 20 owned up to having snoozed while on the toilet at work.An exhausted one in five have even fallen asleep while in the middle of reading to their children.
One in three dads is under heavy pressure as worries about job stability impact - indeed, 42 per cent have used energy drinks to power through the day.
Finishing the family's left over food, ordering takeaways at work and hours spent lazing in 'dad's chair', are just some of the habits that have lead one in five fathers to suffer a health scare. And the family unit is suffering as working pressures combined with poor diets led thirty per cent to admit home life has gotten too much for them at times.
The Benenden research found many dads also feel fed up or too tired to play with their children or snap at them as a consequence of being overworked and undernourished.
The study also quizzed 500 young adults (aged 18-30) on their dad's health.
Three out of 10 said they have cause to suspect their father might be suffering from a more serious health issue.
A concerned six in 10 people say their dad isn't fit or very healthy, while half of young adults say their dad is overweight.
In fact, 46 per cent of people say their dad regularly makes a joke about having a big belly and one in 10 has been embarrassed by their dad performing terribly at a school sports day.
A third of people think their dad is stubborn and refuses to deal with health issues unless pushed.
A fifth of fathers confessed they were in terrible shape - 40 per cent feel their health and the hours they work mean they aren't pulling their weight when it comes to family and domestic life.
One in five dads have texted someone they knew were in the same house to save getting up, with the same number regularly finding themselves breathless after running up the stairs.
But the cardiac arrest suffered by top footballer Fabrice Muamba delivered a strong reality check for one in three fathers, alerting them to the need to take their own health more seriously.
''Men are facing an uphill struggle with their health when they become fathers," said Dr Ian Banks, president of the Men's Health Forum.
''The survey shows even their kids know it. Heart disease is the biggest cause of premature death in men.
''We're saying you only live once - if you want to be around to see your kids grow up you need to stay healthy.''