A man who used to weigh 28 stone is backing a campaign to prevent takeaways opening near schools.
Dean Woods said he used to leave school to go to nearby fast food outlets "at least three times a week".
Since then, 32-year-old Mr Woods has changed his lifestyle and lost 13 stone in a year and has backed the Cancer Research UK campaign.
A Welsh Government spokesman said it launched a Healthy Weight: Healthy Wales consultation in January.
Speaking to BBC Radio Wales about takeaways, Mr Woods said the attraction of them were because junk food was "fast" and "affordable" for students on a budget.
He said it was also important to education children about healthy eating so they could make informed choices.
A Cancer Research UK poll of 1,025 adults in Wales found that almost two-thirds of people who expressed an opinion supported limiting the number of hot food takeaways near schools.
The charity is calling for new rules to prevent new fast food outlets from opening near schools.
Mr Woods, from Ebbw Vale, said at school he was always the largest student in the classroom, and he had to have his blazer specially made for him.
He said: "I would eat chips, pizza, Chinese - all these takeaways were near the school and I just couldn't resist them."
After leaving school weighing 20 stone, he continued to gain weight and said at his lowest point he "really didn't want to be around anymore".
Now the new father runs his own Slimming World group and says he wants his baby daughter Aria to have different childhood to him.
"I don't want her growing up like I did as being overweight can be hard and losing weight can be a real challenge," he explained.
Cancer Research UK's public affairs manager in Wales, Andy Glyde, said: "Weight-related cancer needlessly devastates the lives of so many families in Wales. The Welsh Government can help turn the tide with measures that will make an impact by assisting us all to keep a healthier diet.
"An obese child is around five times more likely to be an obese adult. By reforming rules to prevent new fast food outlets from opening near schools, the Welsh Government can make a positive change to the health of our children and the nation."
A Welsh Government spokesperson said: "We launched our Healthy Weight: Healthy Wales consultation in January, which outlines actions to help people maintain a healthy weight.
"This includes creating healthy environments to support people to make healthier food choices."