Men aged 55 and over who drink tend to binge, while boredom in retirement can lead both men and women to overeating, a retirees' group claimed.
The Retirement Planning Council of Ireland (RPCI) stated not having to rise for work could lead to male retirees indulging in a few more drinks than they would have during their working life.
The group reported that 52pc of men over 55 who drink will binge as a more relaxed way of life takes hold.
From its research, the RPCI said the average worker gets back 50 hours a week in retirement.
But for retired men and women with no regular post-career activities planned, boredom can set in and overeating can lead to health problems.
Dietitian and healthy lifestyle course specialist of the RPCI Sarah Keogh said: "With much more time on their hands, retirees can easily fall into the habit of drinking more than the recommended daily allowance and snacking to fill up the day.
"The key health concern is that alcohol consumption affects sleep and regular interrupted or lack of sleep has been linked to the early onset of dementia as you age.
"Overeating means extra weight and that can lead to problems with joints and mobility as well as putting pressure on the heart."
The group said establishing "new habits" when retiring is "essential in helping to stay healthy into old age".
Signing up to healthy hobbies is recommended by the RPCI as a way of avoiding bad habits.
The not-for-profit group also stated there was a "common misconception" that those in their 20s needed more protein than those in their 70s.
The RPCI stated that including protein in every meal could assist older men and women to meet their daily requirements of protein to preserve muscles and bones as they age.
"During your working life you may normally buy or prepare lunch," Ms Keogh said.
"At home, in retirement, you have access to a fridge full of additional food.
"It's not uncommon to becoming susceptible to eat due to boredom.
"Limiting snacking, or making sure you get out of the house regularly, is important in keeping up some of the good habits you had at work."
The RPCI also stated that older adults should consider weight training exercises to maintain and build muscle to assist those with brittle bones or osteoporosis.
Moderate exercise combining weight and aerobic training would allow older people to main an active lifestyle in retirement, the group said.
Ms Keogh advised a "healthy lifestyle after retirement" advising retirees to attend a course with the RPCI, to consult with a dietician or doctor and to develop a suitable exercise and diet programme.