Les Price, 43, had to pay for the extra space when flying to Ireland and back as airline policy dictates anyone over 20 stone has to book the extra space.
But when he got to the airport the staff didn’t seem to have any idea about the rules and on the journey home his seats were two rows apart.
He had already faced embarrassment on his flight out when he was allocated an aisle seat and a window seat, with another passenger in the middle.
“When I got to the airport I had to explain to all the staff why I had two tickets, they didn’t have a clue,” he said.
“When I finally got on the plane one was an aisle seat and the other was by the window – in a three-seat row.
“On the way back from Ireland one seat was in row 17 and the other in row 19.”
Mr Price says it is just one of the many everyday frustrations he has faced because of his weight which ballooned after an industrial accident that left him briefly housebound.
Mr Price – who says his days of eating a 16in pizza by himself are behind him – will have his diet battle played out before a TV audience tonight on Wales’ Weight Clinic, part of BBC’s Live Longer Wales season.
The widower, who sleeps downstairs because he can’t manage the stairs, said: “From the age of about 10 I put on around a stone each year it seemed.
“But I was the same as everyone else, working, playing rugby, training, so I wasn’t inactive. I’d work 70 or 80 hours a week and play rugby on a Saturday. I wasn’t a layabout.
“Then I had my accident and hurt my back, I was contracted out to the water board at the time from Daniels in Pontypool, and that really knocked me.
“I lost my mobility, developed sciatica and I didn’t get out of the house for three months.
“Even if the boys took me out they would pick me up and drop me off – and when I was at the pub they’d go to the bar and get my drinks for me.”
He piled on 4 stone in nine months. Physiotherapy, acupuncture and swimming failed to ease his pain. Then in 2009 his wife Zeruiah died of cancer.
Turning to comfort eating, he said: “I fell into a depression, I couldn’t be bothered to cook, would eat takeaways and want to treat my stepdaughter Charlie because her mother had died.”
“When I was working, I had to get the calories in. I’d be up at 5am and have a cooked breakfast later. I also worked for a bakery, which involved physically hard lifting, moving things around.”
Mr Price, from Brynithel near Newport, Wales, said: “I want to be out there working,” he says. “I feel guilty my partner is out there working all she can. Christmas is coming up and I feel awful I can’t do anything to help. I know a lot of people work the benefits system – but I want to be out there, not stuck at home.”
Earlier this year Dr Bharat Bhatt suggested airlines should introduce “pay as you weigh” pricing for plane tickets.
Charging overweight fliers more would help carriers recoup the cost of the extra fuel required to carry them, he said.