anger

i don't know why do i get angry so easily over a small thing. i get angry to my mom today just because she tell a joke about my eating habit. i have some weight issues and tend to feel stress when the number goes up. i'm working on my weight these days, i almost never skip my daily work out. i love snacking and always have snacks stock at work. I share my snack with my friends but my mom makes fun of me like if i eat all the snacks by myself. I feel really upset and before that, i weight my self after i dinner and as i expected the number goes up. i was thinking "hey maybe as long i didn't starve, it's normal to have my weight goes up after i eat. the weight probably will back to normal on the morning". but after hear my mom's joke, i don't feel good anymore, of course my sis and dad sided with with my mom after seeing me get emotional. for the my angry emotion is just unreasonable and i should brush it off, but i just can't control my emotion, should i bottle it up? am i wrong for being offended by their jokes? since "it's only a joke?".