When I was first diagnosed with major depressive disorder, I could barely eat anything. Little by little, after 3 months, I got my appetite back. I lost some weight at that time. Then, I fell into depression again, got better, relapsed... My doctor then changed my diagnosis and started treating me for bipolar disorder. After that, I quickly gained weight, mostly because of the meds. Now, whenever my mood starts to go down, I tend to start eating more to feel better. I stop exercising and binge on ready-to-eat meals. Depression tends to cause weight gain for me.