Diet pills are really becoming popular all over the world as more and more people are now using it to become slim and beautiful. However, diet pills can have various side effects if taken excessively. There are many side effects of diet pills like absorption of fats, diarrhea, oily stools, deficiency of Vitamin A,D,E,K and increase in blood pressure. If you are taking diet pills you need to take them only for a limited period of time so that you can achieve the results you want but later on try to keep your health in check naturally without using diet pills.