It's a common perception that taking multivitamins can make you gain weight. At least part of the effect could be due to the presence of zinc in vitamins. Zinc is an element which is essential for human nutrition. The body uses it to support the immune system, among other things, and it gets depleted during times of physical or emotional stress. People and animals deficient in zinc need to eat about twice as much food to gain the same weight as non-deficient members of their species. Therefore, if you are zinc-deficient and start taking vitamins, you could see a weight gain. Does that mean you should avoid zinc to lose weight faster while dieting? Not unless you want to get sick!
Zinc Facts | Periodic Table