According to NYC & Company, New York’s tourism board, there are 18,696 restaurants in New York City (the five boroughs).
There are somewhere near 10,000 places in manhattan to eat something. This includes fast food, deli’s and other quick food. There is a large range of places to obtain sustenance in NYC.
Diet, whether one is on a diet to lose weight, control sugar, vegan, vegetarian, pescatarian, kosher, halal… you name it it can be satisfied in NYC. In fact I have lost weight in NYC. Luckily, walking is available, encouraged, required and necessary.