Claire Alsop, 31, ballooned to 21st 9lb and a dress size 26/28 after having her two children, Noah, six, and four-year-old Ruby.
She has lost a total of 11st 7.5lb since joining her local Slimming World club in January 2011 - despite being constantly surrounded by the celebration cakes she bakes for her friends and family.
Ms Alsop said her weight was beginning to cause her problems with her health and made her worry about the future.
She said: “I was having severe health problems and I wasn’t even 30.
“I couldn’t stand up to make my cakes for more than 10 minutes before my back ached and I’d need to sit down.
“I started thinking about my 40th birthday and wondering how big I’d be then. Would I be 35st or even more? I thought ‘Am I going to see my kids grow up? Will I ever meet my grandkids?’ and I knew I had to do something.”
Ms Alsop joined the Brinsworth Slimming World group with a friend after trying numerous other diets and meal replacement plans without success.
“It was my last chance before I went to the doctor’s to ask for something more serious,” she said.
Ms Alsop said she was amazed that she could still eat her favourite hearty British food and still lose weight. She lost 8lb in her first week and has since slimmed down to 10st 1.5lb and a dress size 10/12.
She said: “I always tell people that I’ve literally eaten myself thin because I have. I love hearty British food like steaks, stews, cottage pie - anything with potatoes - and I’ve still been able to eat all of my favourite meals just by cooking them a bit differently.
“It fits in perfectly with our day-to-day family life because we can all eat the same meals and I am never hungry.”
She said she has even been able to continue baking cakes without it affecting her weight loss.
“Because I’m not hungry I don’t feel the need to pick at the off-cuts of sponge or finish off the buttercream, but if I want to do that every now and again I can - no food’s off limits, so I really can have my cake and eat it,” she said.
“I make lower-fat cakes too and love swapping recipes with the other members at my Slimming World group.”
Ms Alsop said her weight loss has transformed her family life - allowing her to be more active with her children and seeing her husband Paul, 30, also losing weight.
She has taken up running and took part in a 10km race for a local cancer charity.
She said: “I didn’t want my kids to be embarrassed or bullied because of my size. Now they’ve got parents they can be proud of.
“I used to let their lives pass me by but now I don’t miss anything, we’re out and about all the time - on the trampoline together or down the local park - I’ve got lots more energy.
“I’m participating in their lives now rather than spectating and they’re healthier too - they love fruit.”
She added: “I’ve realised that there’s nothing you can’t achieve if you put your mind to it.”