Tummy(Fat deposit on abdomen)

My unmarried brother who is of 40 years medium built (168cm height 65kg weight)has a Tummy (Fat deposit on abdomen)which is not getting reduced even after going for long morning walks, though he is very moderate and meticulous in the in take of balanced fibrous food (taking fruits,vegetables). He sits on computer for a long time, being posted in the Office also for 3 hours (1hr 30 minutes to & fro)in the Bus while commuting 5 day a week.
He had mumps in his teenage & because which one of his testicles(left)had shrunken too much. He used to dring alcohol during the age 25-35. Now his doctor(allopath)has told him that his male hormonal level(testesterone) is in the lower limit (still normal) but need to take care avoiding further reduction. However he not feeling fatigue or tiredeness.
When he was prescribed Nuvir (oral testesterone) & took for7 days he had a drastic improvement of muscle mass/ tone otherwise he used to have weaker n underdeveloped muscles.
Additional symptoms: He has a dry skin (heredetory) even after taking sufficient water intake, it doesnot get improved.
One he was on Nux Vomica-30 for a week, he had some improvement- interms of reduced tummy & improved dry sking conditions.
Sleep , digestion ,bowl movement are absolutely normal.

Could you please suggest some homeopathic remedy for reducing his Tummy (fat deposit on the abdomen)which is probably due to testesterone insufficiency.