"Weight training may trigger metabolic changes in the body that help maintain a healthy weight and reduce the risk of Type 2 diabetes, according to a study conducted by researchers from the Boston University School of Medicine and published in the journal Cell Metabolism." http://www.naturalnews.com/023900_training_strength.html
"Resistance exercising including weight lifting can strengthen the brain. Apparently weight training exercises produce a release of a special neuro-protective protein called Brain-Derived Neurotrophic Factor (BDNF). This is according to new study presented at annual meeting of the American College of Sports Medicine. Weight lifting exercise caused the release of this nerve protecting protein that helps to support the survival of existing neurons in the brain, and encourage the growth and differentiation of new neurons and synapses." http://www.medicues.com/news/
"Research suggests strength training has a lot to offer some teenagers in terms of health, fitness and fun," says Barbara Brehm-Curtis, Ed.D., a professor of exercise and sport studies at Smith College in Northampton, Mass.
Teens who work out with weights, as well as exercise aerobically, reduce by half their risk for sports injuries. Weight training also helps improve sports performance. It boosts bone density and strengthens tendons, Dr. Brehm-Curtis says." -Yale School of Medicine http://www.yalemedicalgroup.org/stw/
“…aerobic exercise and weightlifting have been found to produce endorphins, the body's natural feel-good chemicals. What's more, according to Harvard psychiatrist John J. Ratey, M.D., author of Shadow Syndromes, a book on subtle mood busters, a single workout can raise your brain's levels of the antidepressant chemicals dopamine, serotonin and norepinephrine. And several studies, including one at Duke University, have found that, at least for some people, regular exercise--even brisk walking--can combat depression as effectively as taking certain medications.” http://findarticles.com/p/articles/
“Studies attest that strength training, as well as aerobic exercise, can help you manage and sometimes prevent conditions as varied as heart disease, diabetes, arthritis, and osteoporosis.” –Harvard Medical School http://www.health.harvard.edu/special_health
“Researches from the Stanford University School of Medicine found that regular exercise provides improvement in general quality of sleep, quicker sleep-onset, longer sleep duration and feeling rested in the morning.” http://www.emedexpert.com/tips/exercise.shtml
“Q. What Can I Expect From Strength Training? A. You'll feel stronger with strength training, and find it easier to be physically active. You'll have more energy and you'll probably lose weight, depending on how regularly you work out.” http://teens.webmd.com/strength-training
“For kids, what are the benefits of strength training?Done properly, strength training can:
http://www.mayoclinic.com/health/strength-training
“Q. What Can I Expect From Strength Training? A. You'll feel stronger with strength training, and find it easier to be physically active.
You'll have more energy and you'll probably lose weight, depending on how regularly you work out.” http://teens.webmd.com/strength-training
"As such, a number of sports medicine organizations have stated that properly supervised weight training programs with appropriate technical instruction are both safe and effective for children and adolescents.

“While each muscle group needs adequate recovery time, you can still work out every day by alternating the part of your body you target.” http://www.livestrong.com/article/