Fat March is an American reality television series on the ABC network, based on the UK Channel Four series Too Big To Walk. It premiered on August 6, 2007, and ended on September 10, 2007.

The show focuses on 12 individuals attempting to walk from the starting line of the Boston Marathon to Washington, D.C. for a prize of US$1.2 million.

The show focuses on teamwork by starting with the initial $1.2 million prize, which is to be divided evenly among each contestant to finish the walk. However, at the end of each episode, contestants have the opportunity to nominate any of their team for removal from the walk. Any time someone is voted out, is physically unable to continue, or chooses to stop, each remaining individual's share is cut by $10,000. Participants can choose to vote for no one. It only takes one vote for a person to be ejected; thus if 11 people vote for no one, but one person votes for someone, that one person who received one vote is eliminated.

Fat March received mixed reactions from fitness experts. Cardiologist James Rippe called the show "dangerous for lots of reasons" and said that it "sends a message that walking is painful, you get blisters, you get hurt and it's humiliating. They've made a spectacle of people who did this with all good intentions."