For people who are already trained, changing the amounts of carbohydrates and fats they eat—while keeping total calories and protein the same—does not lead to meaningful differences in muscle growth over eight weeks.

Whether you eat a lot of carbs or very few, as long as you're getting enough calories and protein, your strength and muscle growth won't be different after 3 months of lifting weights.

Whether you eat a lot of carbs or very few, as long as you’re eating the same total calories and protein, you’ll gain the same amount of strength and muscle over several months of weightlifting.

Whether you eat a lot of carbs or very few for months, your strength and muscle growth won’t change — as long as you’re eating enough total calories and protein.

Carbohydrate intake has no significant effect on muscle hypertrophy when protein and total energy intake are held constant.

Eating more carbs doesn’t make your muscles grow bigger when you’re already getting enough protein and calories — your muscles respond more to lifting weights than to how many carbs you eat.