I dunno how swimming affects the body, but I know that exercise can add body mass.
Are you doing any exercise now? I do NOT mean by this post that I agree with your mother - actually the exact opposite, but it sounds like you're stuck in a situation where you are being forced to be subjected to her.
Maybe you could start exercising on a regular basis. The reason I say this is NOT because of how you look or how you weigh. It's because it would get your mother off your back a bit, you'd have a defence against her and something to say to your doctor. It also MIGHT lower your cholesterol and increase your health. Personally I have adopted exercising 2 times a week or so at a gym, even this has made me feel better EMOTIONALLY - apparently it has a similar effect to depression medications and some therapists even prescribe it!
Gentle hugs, and best of luck dealing with this situation
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Yesterday I was so clever, so I want to change the world.
Today I am wise, so I am changing myself.
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