Does taking herbal medicine make you gain weight?

Lately, I've been feeling chronic fatigue, decreased concentration, and lack of energy. Resting, eating, and sleeping don't seem to help much. Since I don't have any particular illness, I'm thinking about taking herbal medicine from a Korean medicine clinic. However, I've heard from people that taking herbal medicine to boost energy can improve appetite and cause weight gain. I'm currently concerned about belly fat and cholesterol, so I can't afford to gain more weight. Does taking herbal medicine really cause weight gain?