Up in the Bronx, you can get great Manhattan chowder at the Sea Shore restaurant on City Island. Their menu also shows steamers, but you can get steamed littlenecks if you ask. Dinners come with cups of soup, and you can upgrade to a bowl for 25 cents, but can probably get a free upgrade by just asking for it. I eat it when I can't get Manhattan, but I don't get excited over it. Available in zillions of restaurants, and in cans.
Some companies make low-fat versions.
Clams don't have fat, but milk and cream do. Vaughn Knowles and Noah Gourlie cook clams and corn on a hardwood fire. The big pots are used for lobster. It's open from late April through October. If you're coming from the west, take I-95 to exit 57.