Why are girls so sensitive about being fat?

as above. my pov is that weight is something that can be changed with the proper lifestyle and discipline. if you're unhappy about it, then do something about it instead of being sensitive about it.
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+1 y
just did some reading and found that more than 75% of Americans are overweight and 1/3 of Americans are obese. a horrifying figure.
Why are girls so sensitive about being fat?
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