Male Speaker: What will strength training do for my weight gain? Taras Raggio: Strength training will build muscle and reduce fat. Strength training stimulates the muscles so you will bulk up instead of fattening fatten up. Some underweight people are afraid of strength training exercises because they are afraid they are going to gain weight. What they don't realize is once you do strength training exercises, doing exercises in general makes you thirsty and makes you hungrier so you want to eat more.