Why is curvy magazine talk for fat?

Today I saw an add that said curvy jeans so I looked at them and it showed women who were obese and not any were near curvy.Honestly I get sick of hearing about skinny vs curvy,you can be skinny and have curvs.Its all a matter of your body shape.Like me I have curvs and a portioned body but I'm only 124.Some girls have straight bodys others have curvs and some are anorexic some are skinny,chubby,fat ect......
So why is curvy magazine talk for fat?(no rude commets not trying to be rude or anything)
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Salon Northampton MA