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Diet and Nutrition

Healthy height and weight for a 13yr old boy?



I`m 13 years old and am about 4`7" or 4`8". I don`t mind my height too much as many of my classmates are only a few cm/inches taller than me, but I weigh like 68 pounds.

How underweight am I, and how can I gain weight? I do a fair amount of exercise (swimming) and eat healthy, but I just can`t grow! What should I do?


I can hear your frustration when you state that "I just can't grow!" So, first of all it is important to realize that during adolescence biological changes (such as increases in height and weight, building muscle mass, and sexual maturation) happen at different ages, duration, and pacing for everyone. For boys, this can mean having a growth spurt between ages 10.5 to 16 years old. During a growth spurt, you can add on about 12 to 13 inches in height as well as double your muscle mass between the ages of 10 and 17 (which will increase your weight).

Secondly, you asked "how underweight am I?" In addition to the scale, health professionals' judge healthy weight and height using a growth chart which compares your growth over time (from birth). If you have consistently followed the same growth curve from birth, you are in a healthy range for your body type. Another tool we use is the body mass index or BMI (an estimate used to determine if a person may be at health risk due to their weight). In children, a BMI under the 5th percentile or over the 85th percentile indicates health concern. Since you weren't definite on your height, I calculated your BMI using both 4'7" and 4'8" using the on-line tool at http://pediatrics.about.com/cs/usefultools/l/bl_bmi_calc.htm It said that at 4'7" your BMI is 15.8 (the 8th percentile) and considered to be a healthy weight. At 4'8" your BMI is 15.3 and falls below the 5th percentile which is considered underweight.

So, to determine if you actually are underweight it would be helpful to have your parents take you to see a pediatrician for an evaluation; then it would be a good idea to see a dietitian for some individual help. Your diet and exercise patterns would need to be evaluated. It is also important to consider if you are in a growth spurt (sometimes we grow taller and thin first, then the weight catches up as the height slows in growth). Since you state that you already eat a well balanced diet and swim, you are off to a good start. You (along with your parents and a dietitian) will need to make sure that you also take in enough calories to support your continuing growth and ensure that you are getting the proper nutrients you need (including protein, iron, zinc, and calcium for development of bone and lean tissue). Weight gain should be gradual, over time. Small increases in healthy foods will help you put on weight. Do not go for the "quick fix." Remember to try not to fill up on "junk foods" (chips, fried foods, pop, candy); let your calories continue to come from nutritious sources (fruits, vegetables, whole grains, low-fat dairy, lean meats, nuts) instead. If you visit the MyPyramid.gov website, you can tailor a diet to meet your needs according to your age, gender, and activity level. Go to "my pyramid plan" at http://mypyramid.gov/mypyramid/index.aspx.

Also, consider trying other exercises in addition to swimming. Weight bearing exercise (such as walking or running) will help build muscle and add to your body weight in a good way.

I hope this helps put things into perspective for you. Be patient with yourself and be sure to speak to your parents and doctor about your concerns. Good luck!

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Response by:

Jane   Korsberg, MS, RD, LD Jane Korsberg, MS, RD, LD
Senior Instructor of Nutrition
School of Medicine
Case Western Reserve University