Being sincerely supportive, as you seem to be, is very important. However, until she find a way to love herself nothing is going to change. It doesn't matter if your thin, curvy or obese, if one doesn't love themselves for who and what they are it's not happening. Your wife NEEDS to find ways to increase her self image. Exercise is a great way... Now she may not be into going to a gym, or running, there are all kind so things you can do. You could start out by suggesting an evening walk, a family bike ride.... just get up and move and she'll feel more alive and invigorated. If she doesn't work, perhaps she needs to find a part time job to make her feel good about herself, the key is she needs to help herself, she's the only one that can do it.