If you want to become very strong, you should lift heavy weights, eat carbohydrates before you lift and eat plenty of protein afterwards. Normal amounts of insulin help muscles grow, and eating carbohydrates causes your blood sugar to rise, which, in turn, causes your pancreas to release insulin. Taking in large amounts of protein after a workout helps muscles to recover faster from hard exercise, so you can do more hard work and grow larger and stronger muscles (Journal of Physiology, Volume 573, 2006).
To increase muscle strength, the weights you lift must be heavy enough to cause muscle burning while you lift and your muscles to feel sore on the next day. The soreness is caused by damage to the muscle fibers themselves. Most athletes quickly learn to lift lighter weights on as many days as it takes for the soreness to go away, and then lift very heavy weights again. The faster muscles heal from hard workouts, the more quickly you can go back to lifting heavy weights and the stronger you will become.
Insulin brings protein building blocks, called amino acids, into muscles to increase the rate of healing. Eating carbohydrates raises blood insulin levels. Protein is the building blocks for all tissues, particularly muscle. So the faster and more protein you can bring into muscle fibers, the more quickly they heal and the faster you can go back to your heavy lifting program.