How long does it take for thin people to keep fit and gain muscle?

For thin people, the initial physical contact in fitness training will lead to temporary weight loss, but it doesn't matter. Pay attention to nutrition, rest and strength training. Stick to it for 4-5 months and gain at least 5 kilograms. Then you will enter a period of slow weight gain. At this time, you need to constantly increase the intensity of training, stimulate muscle growth and stick to fitness.