I've never been fat, but used to struggle to keep a "racing snake weight" which for me means anywhere between 69 and 71Kg... occasionally I used to balloon to 77 kg and had to resort to dieting, as well as my menu of 200+ km a week on the bike.
Then just over a year ago I cut meat and since then I have been steady at 71 kg, including over the Christmas period (twice). I don't think it's meat per se, but all the crap that goes with it... a pork pie, burger with chips, sausages with loads of brown sauce.
I eat more carbs that I probably should, albeit with loads of fibre, but carbs don't seem to inflate me in the same way as a protein (and crap) rich diet used to.