She is on a diet for fear that she will put on weight.
我怎么才能发胖？
How do I gain weight?
“我就算吃得再多也不会发胖。”“你在那一瞬间成了世界众人的敌人。“
"My metabolism is such that no matter how much I eat I don't put on weight." "Just now, this second, you've made enemies of people throughout the world."