I LOVE Indian food but between the salt and the grease, it's hard to make "dietetic" choices.
More basmati rice and less curry is a way 'round the problem.
Tandoori dishes, which are basically broiled/roasted meats are good, especially chicken. I find them a bit too dry but that means less fat.
Some curries can be naturally lower in fat unless they add a ton of ghee. For example a Shrimp Vindaloo would be less greasy than a Lamb Vindaloo.
If you go to a BUFFET (which I adore), you can pick the curries that seem to have less or no oil floating on the top.
And, as DING said, amplify the Vegetarian and shy clear of the deep fried samosas and fritters. But wow, is there ANYTHING so tasty as a meat samosa smothered in that green coriander/mint sauce.