Sometimes we don’t realize how important other people are to us. As human beings we have a fundamental need to belong and to be close to other people. It’s painful to be rejected by your group, to feel disapproval from your friends. This could be enough to prompt you to gain the weight back. Psychological studies have shown that rejection and disapproval are often associated with self-regulation failure as well as self-defeating behaviors.
We all want to belong to groups. We all need to belong to groups. We also have a tendency to keep our own actions in line with the way the important groups in our lives think is good. So, you can see how the cause of your weight gain could very well be the jealousy of your friends. Perhaps without realizing it, you are gaining weight back so they would approve of you once again.
Maybe before gaining the weight back, you can try talking with your friends. You could explain how important weight control is to you and how much you need them on your side if you are to be successful. This should make a world of difference. It might be enough to diffuse the jealousy and bring your friends around to your way of thinking.