crunches for tummy trimming?

You need to do this properly. There are techniques, but they’re tough, and you have to stick with it. Crunches are best, but work out realistically. There’s a Qigong (Tai Chi) crunch which is hard at first. You lie flat on your back, and grab your toes, with your legs straight. It does work, and it allowed me to touch my toes standing up for the first time. ( I was 44 at the time.) Be careful, though. If you’re really unfit, you need to build up to this level of exercise. You don’t need injuries and heart strain as well as the tummy problem. You might need an instructor, if you lack confidence in doing some exercises. There are ways of preparing for the more demanding exercises. Most people don’t do their exercises properly, and that’s one of the reasons the workouts don’t show results. Get it right, and it will get you right. *****Important: Get your diet organized. You really do have to do this. Lots of green vegetables, lay off the junk food, fats, and take proper supplements, strictly according to dosage. No garbage, and reduce the sugars.