Gyms in and around Kolkata.

I'm back in the city and looking for a gym to join. Location isn't a big factor, but its better if its around airport or salt lake area. The big factor, however is the trainer. I'm looking for gyms with knowledgeable trainers who can work scientifically and actually knows what they are doing.

I've no plans to become a hunk or build a body like Hugh Jackman, I just want to loose around 20 Kilos of weight. So I think any gym would work until the trainer is good.