How do you convince a friend to stop overfeeding?

I'm not sure that the scare tactics will work. Most people understand perfectly well that overeating/overfeeding can lead to health problems.... but that doesn't stop them, ya know?

So maybe approach it from a different direction? Tell her about an article you read about how dogs love green beans as treats and that she should see if hers does. I can find you some links if you want. Cutting out even one snack a day with something healthier could be enough to help out his diet.