If you want to add the strength, your muscle needs “fuel” that comes from what you eat, junk food excluded. A proper diet has combination of protein – rich foods and a low calorie that mean you consume protein-rich food but it can be burned totally instead of trans-fat. According to Academy of Nutrition and Dietetics, to gain muscle, an adult needs between gram to gram per 1 kilogram of weight daily in average – that is between 7 and 9 gram of protein per 11 pounds of weight. Therefore, you should know how many calories you burn during the day, and then consume 500 calories and more than to give extra energy for your muscle to get stronger. One more thing, simply eat healthy to get as much vitamin or mineral as possible by plenty of vegetables, lean meat, etc. This is also a common tip on how to increase muscle strength naturally that you should apply.