Jimmy Kimmel is trying to get in shape for his wedding.

The talk show host will tie the knot with Molly McNearney next month and has cut back on all of his favourite foods in order to look his best on the big day.

A source told Us Weekly: ''He cut back on his beloved pizza, pasta and barbecue. Fish and lean means like bison and turkey are on the new diet. He also keeps a treadmill in his office and does cardio daily.

''Molly's encouraging him and it's working.''

The 45-year-old TV personality proposed to his long-term love - a co-head writer on his show 'Jimmy Kimmel Live' - last August, and the pair are set to tie the knot on the weekend of July 4.

He recently hinted: ''It'll be mostly a family affair, and there will be a Catholic priest officiating ... I'm not that involved with the wedding planning, but I will be there.''

The pair have been dating since 2009 and he popped the question while they were holidaying in South Africa's Kruger National Forest.