Does weight training increase bone density?

Absolutely: Evidence shows that exercise help build and maintain bone density at any age. Studies have seen bone density increase by doing regular resistance exercises such as lifting weights for 20mi, 2-3 times a week. This type of weight-bearing exercise appears to stimulate bone formation via bone stimulation through muscle contraction.

Somewhat: Weight training can produce a modest increase in bone density over time. Generally this is not sufficient to significantly treat osteoporosis. However maintenance of leg strength is important in preventing falls and fracture.