Adama joined West Ham in January from Fulham, having previously played for Nuno at Wolves.
Well known for his physique, Adama has been told to stop weight training by his manager.
Ahead of tomorrow's trip to Fulham, Nuno said: "It's incredible (his physique), it's genetics. (But) his genetics has been like this for some time now and he should avoid the gym.
"I've told him to stay out of the gym. It's one of the things that I think he needs to realise. It's enough weight that he carries.
"He'll do prevention work (in the gym), but he's not in there lifting weights.
"For example, (Under-21s defender) Airidas Golambeckis, he spends hours in the gym - we have to get weight on him. He's the one that needs some muscle, it's the other way around."
On Adama's playing chances, Nuno added: "Traore's unique. There are not many players in world football with his ability, pace and skills in one v one situations.
"He's a talent that we have to take advantage of, but it will take time. He has to adapt and understand the dynamic of the team. But he's proven in England and in the Spain squad not long ago, so we're talking about a high-level player."