2 anwers:
1) she is lie about her training. And do almost nothing. She probably sitting somewhere and eat ice cream.
2) she lie about her diet. Fastfood and similar crap. A lot of it.
Its trivial logic. Fat cannot become from nowhere. The only way to get it - food. Also gym will decrease your calories. So....weak trainings and a lot of food - no other answers. And obviously she don't show you full picture. It's hard for people to admit their weaknesses. More funny describe this as MIRACLE. "I eat nothing and work everyday and still fat as truck, how it could be?" Oh yes. How it could be lol?