A man lost over half a stone despite eating 10 slices of pizza every day for a month - and is now more ripped than when he started.
Personal trainer Ryan Mercer, 34, ate pizza for breakfast, lunch and dinner and managed to lose a whopping three and a half kilograms during the 30-day challenge.
He took on the challenge to show how calorie deficit diets allow people to lose weight without restricting their favourite foods.
Ryan, from Bangor in Northern Ireland, carefully planned his diet and made all the pizzas himself, while maintaining his usual exercise regime.
He said: "January is a tough month for people when it comes to fitness goals.
"I aimed to highlight not only fat loss about calories in and calories out but that it's also not about restriction.
"We don't have to restrict our favourite foods to get results and I also wanted to encourage more people to prepare their own food."
Ryan's usual diet is a flexible approach to eating, with a healthy protein intake, and seven to 10 portions of fruit and vegetables each day.
But for the challenge, Ryan ate nothing but pizza.
He added: "I consumed pizza for breakfast, lunch and dinner every day.
"I had two pitta pizzas and one larger dough-based pizza per day, this equated to roughly 10 slices per day.
"Additionally, I left room for additional snacks."
Pizza is one of Ryan's favourite foods, but due to his busy schedule, he found it difficult to make time to prepare the pizzas himself.
"The hardest part of the entire diet was the preparation," Ryan said.
"Pizza is one of my all-time favourite foods, so I enjoyed eating it all month, although I did ensure I had a large variety of different pizzas to give myself some variance."
As he prepared everything himself, Ryan spent just under £10 per day on food.
He added: "I home-cooked everything. The estimated daily cost was around £6-a--day for two pitta pizzas, and one dough-based pizza and three side salads.
"Additionally, I spent around £2 or £3 per day on snacks."
At the end of the month, Ryan became leaner, which surprised many of his followers online.
He said: "This was a carefully planned dietary strategy. I designed a system, and this is what got me to my goal.
"Daily calorie intake was set at 1800-2100 Monday to Friday, 2,700kcal Saturday and Sunday, daily protein target 140g per day, daily fruit and vegetable portion goal, seven portions minimum per day."
Ryan only recommends the diet if it suits the person's lifestyle citing "everyone is different".
His video reveal garnered over 2 million views online and has generated a huge response.
He said: "I feel [that the video] has highlighted the confusion among the masses when it comes to fat loss and nutrition.
"I've had some negative comments, some very funny ones and of course some positive feedback.
"One thing we have in common is we all eat food so everyone has some sort of opinion when it comes to nutrition."