Do I need carbs to build muscle?
You do not need high carbs to build muscle, but carbs are often useful. Resistance training can be done on lower-carb diets, but many people train more intensely, recover better, and tolerate more volume when they include enough carbohydrates.
The top priorities for muscle gain are progressive training, enough total calories, enough protein, and enough recovery. Carbs support that system by helping fuel strenuous sessions and replenish glycogen, especially when training volume is high, sessions are dense, or conditioning is included.
Carbs can also support partitioning indirectly. Better training performance means a better muscle-building signal, and fuller glycogen stores can help you sustain more productive work. They do not replace protein or training, and they do not bypass calorie balance, but they can make the whole hypertrophy system work better.
If a low-carb diet improves adherence and your performance is fine, it can work. If your workouts feel flat, pumps disappear, sleep worsens, training volume drops, or you keep craving carbohydrates, a moderate carb intake may be a better tool.