Naan is essentially a refined flour flatbread, leavened with a bit of yogurt and cooked in a super-hot tandoor clay oven. It's softer and fluffier than roti canai, and at 270 calories for a plain piece it's not outrageous on its own, but it's almost pure carbs with very little to slow down digestion. The dough has a small amount of oil or ghee baked in, which accounts for a chunk of the calories. Most of the calorie damage actually happens after it leaves the oven, when the mamak uncle slathers butter on top. That's where butter naan at 370 cal and cheese naan at 430 cal come from. These are estimates though, honest, because every mamak has a slightly different recipe and a very different definition of how much butter is "enough".
The thing that really changes the maths is what you pair it with. One naan with a bowl of dhal (around 150 cal) is a reasonable meal. One naan with a heavy mutton curry or korma, plus another piece because the first one went too fast? You can easily hit 700 to 900 calories without thinking about it. Swap butter naan for plain, you save roughly 100 calories. Order one piece instead of two and you save another 270. If you're eating naan as part of a restaurant meal, that's probably your entire carb budget for the sitting, so maybe skip rice on the side, bro.