A circle of melanin on the neck of fat people may be due to excessive friction, acanthosis nigricans, etc., which can be improved by strengthening care and medication. 1. Excessive friction: the folds on the neck of fat people are relatively more, long-term friction between the folds will make the patient’s neck melanin precipitation, such patients should first pay attention to light diet, strengthen the exercise, scientific fat reduction, will be controlled within the normal range of weight. You can also apply Vitamin A cream, arbutin cream and other creams on your neck to help lighten the melanin. 2. Acanthosis nigricans: obesity is an important factor causing benign acanthosis nigricans, patients in addition to melanin precipitation on the neck, but also in the armpits, groin and other parts of the local skin color black symptoms. This kind of patients need to lose weight, medication can be used in vinblastine gel, hydroquinone cream, cod liver oil ointment and other ointment for local application, serious cases also need to take oral vitamin A and other drugs. All of the above drugs need to be used in accordance with medical advice. A circle of melanin on the neck of fat people need to consult a doctor in time, standardized treatment under the guidance of a physician to avoid the occurrence of adverse reactions.