The organ primarily responsible for regulating metabolism in the body is the thyroid gland. Situated in the neck, the thyroid produces hormones, such as thyroxine (T4) and triiodothyronine (T3), that control metabolic processes, including energy production and utilization. An optimal thyroid function is crucial for maintaining healthy weight, energy levels, and overall bodily functions. Disorders of the thyroid can lead to metabolic imbalances, affecting weight and energy levels significantly.