If you're a young man who lifts weights regularly, eating 1.8 grams of protein per kilogram of your body weight every day is enough to build as much muscle as you can from training—adding extra leucine powder won't help you get any bigger or stronger.

If you're a young guy who lifts weights and already eats enough protein, taking extra leucine pills for 12 weeks won't make you stronger or build more muscle in your thighs than just lifting weights by itself.

If you're a young man who already lifts weights and eats enough protein, doing strength training twice a week for 12 weeks will make you stronger and build more muscle — and taking leucine supplements won't make any extra difference compared to taking a sugar pill.

If you're a young guy who lifts weights and you take 10 grams of leucine powder split into two doses a day, it won't make you eat more or less protein or leucine from your regular food.

If you're lifting weights and want to build muscle, eating at least 1.6 grams of protein per kilogram of body weight every day is the biggest factor that helps — more protein means better results, and when you eat it doesn't matter as much.

If you're a young man who already eats enough protein and works out with weights, taking extra leucine won't help your muscles grow any more — your muscles just can't use more than a certain amount, no matter how much you give them.