Weight loss does not mean that a person has a bad sports training. Many professional athletes are thin and have a weight that approaches the lower limit of the normal range. Often it depends on the sport. So, gymnasts and tennis players are light, while boxers and bodybuilders tend to increase body weight, increasing muscle tissue.
However, ordinary people, BMI is below normal (less than 18.5), as a rule, do not have excess fats or muscle tissue. They need to engage in sports, with an emphasis on strength training and muscle growth, as well as adhering to a special diet rich in proteins and carbohydrates. In this case, they will be able to gain weight mainly due to muscle tissue.
For those who do not seek to increase its weight and make muscle relief, we can recommend aerobic exercise for the upper and lower body. They will strengthen the cardiovascular and other systems of the body, will make the muscles stronger and not too affect the weight.
In general, low weight can not be considered a cause or reason bad physical shape. People with low BMI should play sports and lead an active lifestyle, which will allow him to build muscle, strengthen the body and increase the appetite. Obviously, with any BMI, both high and low, it is better to have a lot of muscle and little fat, than vice versa.