Truthfully, I have no idea how you want to accomplish this without dieting or exercise. The only way to actually lose weight or shrink down the mass in your thighs is through some sort of exercise. Even if it is walking, riding a bike, or doing leg exercises at home. But you can't use exercise alone to lose the fat in your thighs, you need to diet too so that it reduces the fat in your muscles so the exercise will help to tone them up so you can lose weight in this area.