Instead, the successful chef took a look at the types of foods he was eating.
By changing his diet plan, Jamie noticed the pounds start to fall off.
He revealed he swapped large servings of meat for more vegetables to get into shape.
“I lost 12 kilos quite quickly and I didn’t do it through not eating. I ate a lot, more than I was used to,” Jamie told Radio Times.
“I pushed meat down, pushed veggie up, got more sleep and more movement.”
Adding more vegetables into his meals is clearly important to the chef and he released a vegetarian cookbook last year, named Veg.
We all know that eating vegetables is an important part of a healthy diet.
As well as making the obvious change, Jamie suggested eating more nuts helped him trim down.
He added: “They make you half as likely to have a heart attack. Feed them to your kids as well.”
Nuts can be eaten as a healthy snack or to spice up a meal, according to Healthline.com.
The website said: “Though they’re usually high in fat, the fat they contain is a healthy type. They’re also good sources of fibre and protein.
“Many studies have shown that nuts provide various health benefits – especially in regards to reducing heart disease risk factors.”
Jamie focused on making other healthy changes to his lifestyle at the same time.
The TV chef cut back on booze and tried to get more sleep.
He continued: “Your average Brit drinks booze. I’m not telling you what to do, but my rhythm now is only to drink at the weekend.
“It’s about a consciousness and knowing you’re doing something and being more mindful.”