Multigrain" and "whole grain" are two different attas. If you were under the impression that eating multigrain was healthy, you were wrong.
In Whole grain atta all parts of the grain kernel, bran, germ and endosperm are used. The germ is rich in essential fatty acids and b-vitamins; the endosperm, which is mostly starch; and the bran, which, of course, is high in fiber.
In contrast, multigrain atta means that a food contains more than one type of grain, although none of them may necessarily be whole grains. Mostly refined grains i.e. devoid of their natural nutrients and fibre and consisting of only the endosperm.
So how do you choose the right flour?
In order to make sure you are actually getting a whole grain product, look for 100% whole wheat or 100% whole grain. The first ingredient on the ingredient list should be a whole grain.