Just because your goal is to lose weight, don’t think you avoid lifting weights. One of the greatest benefits of resistance training is insulin sensitivity. Insulin sensitivity means that your muscles are receptive to insulin bringing fuel to be stored in the muscle- NO, this does not make you bulky. It actually provides energy for when you move those muscles.
The opposite of insulin sensitivity is insulin resistance which means that your muscles don’t respond to insulin so the fuel is diverted to your FAT CELLS for storage. Increased insulin resistance leads to, not only fat gain, but also diabetes.
Full body, circuit training routines are a great way to get the advantages of resistance training but is about as far from bodybuilding as you can get. Movements using large muscle groups like rows, presses, squats and lunges performed at a fast pace, one muscle group after the other, will improve insulin sensitivity but does not train the muscles to store large of amounts of glycogen like a bodybuilding routine would.
Ideally a 20-40 min circuit training routine followed by 20-30 min of cardio would be a great workout for losing weight AND providing the least stimulation for hypertrophy, or excessive muscle growth.