yeah - cardio. it keeps your strength and you lose fat like crazy. also protein diets. combining them you won't lose your strength. it is essential that you need to keep exercising. I was exercising (mostly cardio and a bit of weight lifting) and I have lost lots of weight and gained some strength (a bit of muscles). then I continued dieting but I stopped to go to gym. both my fat and strength started to go away. so, keep exercising. keep doing cardio and eat right (for keeping fat low). I guess this is not what you have expected to read, but I am not a professional and I tried to help with whatever I could.