I gained weight when using insulin in the 1990's. The only way I could lose the weight was to reduce the amount of insulin I was using. It was necessary to cut my daily carb intake to 130g. I also exercised every day for one hour. It took me about one year to lose the weight. Now I can eat 150g per day, and I still do my exercise. Following a low carb diet and exercising results in lower insulin dosages, and that causes weight loss.