As HTB mentioned, it could have been triggered by the doctor's intervention when she gained weight as a teenager ... thereby making things worse.
It's normal for girls to put on weight during puberty, as metabolism changes and height growth ends. It doesn't have to be a lifelong thing, if the person adopts sensible eating/exercise habits and doesn't have any metabolic or endocrine issues.
Wintertime mentioned antibiotics as a factor in higher rates of obesity. I wonder if the almost universal use of hormonal contraceptives isn't a factor, as well. Then there's a psychological factor, especially in our culture in which everyone's appearance is considered everyone else's business 24/7. (Some guy had a cow the other day on a thread where I said I liked another older lady's haircut. Looney tunes!)
As we learn in Weight Watchers, part of healthy weight loss/weight maintenance is learning what smart food choices are. People can be overweight without overeating if they aren't knowledgeable about nutrition. The other, often bigger, part is learning how to deal with all the *%&^*(@ in your life, including *^&* people, so that you're able to make the smart food choices.
What she is describing sounds like a condition known as poly-cystic ovary syndrome. It’s more than just teen hormones kicking in.
It also makes you insulin-resistant.
What does this sentence mean?