Facts by Age Groups


What’s Happening – Growth and Development

Regardless of the start of puberty, it may continue for up to six years. Boys have approximately two years of growth more than girls. In addition, boys usually have a greater increase in the rate of growth during puberty than girls. As a result, boys have larger bones after puberty than girls.

About 40% of bone mass is build during adolescence. This amount of bone accrued is equal to the amount of bone typically lost throughout later life.

Completion of normal skeletal growth requires adequate production of various hormones (thyroid hormone, growth hormone, insulin growth factors, and sex hormones). Growth of their arms and legs is completed before growth of the trunk. Longitudinal growth of the spine is complete usually by the age 16 to 18.

By the age of 18 in girls and age 19 to 20 in boys, about 90% of adult bone mass is accrued.

Bone Health Tips for Your Teens

Physical inactivity is common among teenagers. Low vitamin D is widespread. Calcium intake often falls below recommended levels due to low consumption of calcium-rich drinks. Many teen diets have the highest share of calories from fast-food places.

Lifestyle risk factors, such as cigarette smoking, alcohol use, and eating disorders, exert a negative effect on bone mass development in the teenage years.

Bone healthy measures for your teens include:

1. Calcium

  • Recommended calcium intake is 1300 milligrams a day.
  • Four 8-ounce glasses of milk will cover the recommended amount.
  • If dairy is not the source of calcium, provide protein from other foods.

2. Vitamin D

  • Recommendations continue at 600 IU per day with no more than 4000 IU per day.
  • Diet may not supply sufficient vitamin D in the fall, winter, and spring; a supplement to diet may be needed.

3. Diet

  • Encourage them to make food choices for balanced diet of protein, vegetables, and fruits for three meals (no skipping breakfast).
  • Limit soft drinks that displace calcium-rich drinks.
  • Limit eating fast foods.
  • Avoid caffeine-containing energy drinks.

4. Exercise

  • Encourage weight-bearing exercise for at least 60 minutes, 3 times per week.
  • Continue in organized sports.
  • Limit television, computer, and electronics time.
  • Promote walking instead of driving once a driver’s license is in hand.

These years may be the most difficult for parental influence with peer pressure and independent thinking trumping healthy habits. At least you can take advantage of influence in the home by providing healthy choices and role models.