Fat and fad

Mari is on a diet again.
She has tried a variety of fad diets: a lot of diet foods, supplements, beauty salon treatments, and so on.
She is now trying "banana diet". It is very simple; the thing only to do is to eat bananas for breakfast. She says, "If I have bananas at breakfast, I can eat any food after then!". I am afraid but I doubt her scientific literacy.

She hates exercising. A few years ago, she decided to train in the gym, but she went to there only once. Sometimes I took her and Ken swimming, but she watched us out of the window of the pool.

Ken is getting fat too. I am trying to exercise him anyway.