Unexplained Weight Gain in Teenagers

Processed foods from fast food restaurants may contribute to a teenager's weight gain.

The teenage years are a time of big change -- from new schools to new jobs, teenagers are likely tackling several new obstacles at once. Body anxiety and weight-related fears may also surface as a teen's body undergoes rapid change during puberty. While your teenager's weight gain may be a normal part of development, unexplained weight gain could be a symptom of an underlying illness. A doctor's evaluation and treatment may prevent more weight gain.

Normal Weight Gain Causes

During puberty, a teenager may grow by about 10 inches, according to KidsHealth. During the same period, a child's weight may increase rapidly. Weight alone is an inaccurate measurement of body fat in athletic teenagers, as a teenager's weight gain may be due to increased muscle mass, according to the American Academy of Pediatrics. A doctor can determine if your teenager's weight gain and current weight are the result of normal development.

Lifestyle Factors

Some weight gain may appear unexplainable, but an evaluation of your teenager's daily life may show that weight gain is the result of little activity and excessive calorie intake, according to the Centers for Disease Control. Your teenager's doctor can help your family adopt a healthier approach to nutrition and exercise. A teenager who has recently stopped smoking is also more likely to gain weight, according to the Texas Children's Hospital. Conditions like menstruation may also cause bloating and weight gain.

Thyroid Problems and Medications

If your teenager's weight has suddenly shifted, a thyroid problem could be to blame, according to the American Academy of Pediatrics. Teenagers with hypothyroidism may experience dryness in the hair or skin, fatigue, depression, muscle cramps and changes in weight, among other symptoms. Some drugs used to treat mood disorders like bipolar disorder or depression may also cause weight gain as a side effect, according to the Texas Children's Hospital. Your teenager's doctor may be able to change your child's prescription to avoid further weight gain.

Polycystic Ovary Syndrome (PCOS)

About 5 to 10 percent of women in the childbearing years may have polycystic ovary syndrome, according to the U.S. Department of Health and Human Services Office on Women's Health. Teenage girls with polycystic ovary syndrome may experience irregular periods, depression, thinning hair on the head and pain around the pelvis. Girls with this syndrome may also gain weight, especially around the midsection. Medications and changes to diet and exercise habits are common treatments for PCOS.