When your blood sugar is high from sugars and starches in your diet, your body responds with insulin. When your insulin level is elevated, your body responds by storing fat into fat cells. It isn't released until the insulin levels fall, but then, the fat is released and you have the opportunity to burn it. If your insulin level is too high too much of the time you may not even be able to access enough energy from your food to feel normal. It is being stored without being used so it can contribute to being tired and depressed. Anything you can do to regulate your blood sugar better and avoid insulin spikes will help. I have been told that a diabetic diet often results in weight loss even for people without diabetes. I can guess that this would be a result of controlling blood sugar levels and avoiding insulin spikes. Cinnamon extract and chromium supplements are supposed to help. Avoid anything diet, especially diet soda, because the artificial sweeteners still cause insulin spikes.

Small changes in the beginning are easier to keep up.

Probiotics would be good to look into, too. People who are overweight don't tend to have as many of the helpful microbes and too much of other, more harmful ones.

Yogic breathing can help. By that I mean learn to breathe throughout the entire volume of the lungs, making sure to get plenty of slow, deep breathing. It is easier to start by laying down on your back and putting a hand on your chest and another hand on your stomach. At first breathe using the muscles of the diaphragm by pushing your stomach in and out. The hand on your stomach should be moving but not the other hand at this point. Most of the blood flowing to your lungs goes to the bottom third of your lungs. This can help with stress and it will help to get more oxygen into your system. It will help with your metabolism and mood. Five minutes would be a good place to start.

Of course, I am not a doctor and do not intend to give medical advice. This is all just stuff I've read about. It sounds like you have already asked your doctor, and didn't get a good result. You may be better off discussing this kind of thing with a nurse. Nurses are wonderful people and they are often much better at handling conversation.