what's your thoughts?

So I am a 175 pound girl at the moment and I normally gain weight easily and I lose weight so my body is very bipolar and I also want to lose weight my boyfriend is telling me to start working out and be healthy because both of my parents have diabetes and its a higher risk of getting it and so he tells me that If i get to a certain point where I've gained to much weight he was going to break up with me because he doesn't want to see me unhealthy and having to have insulin shots what do you girls think?