A new campaign aimed at tackling Northern Ireland's growing weight problem is to be launched by the Public Health Agency (PHA) on Thursday.
The PHA said more than half of all adults in Northern Ireland (61%) are now overweight or obese.
It said obesity increases the risk of developing serious diseases and reduces life expectancy by up to nine years.
The chief medical officer said it was "one of the biggest public health challenges" currently facing NI.
Dr Michael McBride said obesity was "a modern lifestyle epidemic that is threatening our health and wellbeing".
Recent research suggests that many adults in Northern Ireland may be in denial about their own weight.
While 61% of adults are overweight or obese, the Northern Ireland Health Survey showed that 43% of those assessed as overweight felt their weight was about right or too light.
The PHA's new public information campaign will take two approaches.
The first will help members of the public check if their weight is having a detrimental effect on their health and the second will offer practical advice on how to lose weight.
People will be encouraged to measure their waistline and if it is bigger than it should be they will be encouraged to think about the impact their lifestyle choices could be having on their body.
The PHA advises that to maintain health, a woman's waist measurement should not exceed 32 inches (81cm), while for men the limit is 37 inches (94cm).
A dedicated website - www.choosetolivebetter.com - has been developed as part of the public information campaign.
The PHA's director of public health, Dr Carolyn Harper, said: "More than one in two adults in Northern Ireland are now overweight or obese, but many people don't even realise that they fall into this category and are putting their health at risk.
She added that being overweight or obese "increases the risk of developing heart disease, some cancers and type 2 diabetes".
"This campaign aims to help people recognise when they are overweight or obese, explain the health effects, and encourage those who need to, to make small, realistic lifestyle changes that will help them maintain a healthy weight," Dr Harper said.
"Small changes are easier to make and can add up to make a big difference. For example, having smaller portions, swapping to healthier options, saying 'no thanks' to seconds or the children's leftovers, and going for a walk instead of watching TV. Every small step will help people keep a healthy weight and improve their health."
Professor Ian Young, chair of the regional steering group on obesity prevention, said: "A range of organisations have shared ideas and collaborated to develop this campaign, and hopefully it will help encourage people to choose to live better by adapting their diets and activity."
The campaign is due to run until the end of March.