Maybe when you were hardcore training your were able to eat like a horse as your body dissolved the calories instantly with exercise but when you stopped training, you stopped using huge amounts of calories but maybe the large hunger didn't go. My Mrs did that, before she came to scotland she was a gym instructor and was teaching 3 or 4 high intensity classes a day so she was able to pile it in and not put any weight on. When she came to Scotland for 6 months she was still eating like a horse but not doing the classes, she piled weight on, its crazy to look at the photos of her (even though by UK standards she was still a twig). When she got home her family ribbed her endlessly about being fat!!

She took it all off again though as she ate healthy Japanese food and got a job as Trainer again.
Towering in gallant fame, Scotland my mountain hame, High may your proud standards gloriously wave, Land of my high endeavour, Land of the shining river, Land of my heart for ever, Scotland the brave