Why Isn't My Child Gaining Weight

Every time your child sees their pediatrician, their height and weight are plotted on a growth chart. The idea is to see how your child is progressing and hitting their developmental milestones. But for some parents, the chart causes more anxiety than it provides reassurance.

"If a parent sees a dip in the chart because of a temporary weight loss or their child is hovering in a low percentile, they may feel concerned," says Seth Iskowitz, M.D., a pediatric gastroenterologist at Henry Ford Health. "We try to reassure them that children progress at different paces and healthy children can come in a variety of sizes."

What Those Growth Chart Percentiles Really Mean

The growth charts you see at least annually at your pediatrician's office have been around since 1977. The National Center for Health Statistics created them as a way for doctors and parents to track kids' development.

The charts plot a child's height and weight (or BMI), ranking them in percentiles compared to others their same age. For example, if your child is in the 20th percentile for weight it means they weigh as much or more than 20% of kids their age, and less than 80% of them.

Being in the 50th percentile is average height and weight, and that's the goal. "But a child doesn't have to be in the 50th percentile to be healthy," says Dr. Iskowitz.

What matters most is your child's own growth trajectory. "We want to see that a child is continuing on a steady, upward growth curve," says Dr. Iskowitz. "But it's okay if that trajectory is following along in a low percentile-especially if there are other factors, like the parents being smaller than average."

Factors That Can Impact Child Weight Gain

Some children are naturally smaller or thinner than average. If their parents are also small, genetics could be a contributing factor. But there are other reasons why a child may not be gaining weight. "An underweight child may have other conditions that affect their growth," says Dr. Iskowitz.

Some kids simply don't eat enough calories. Although it's very common for children to be picky eaters, many still manage to consume enough calories to grow and gain weight. "I'm more concerned with kids who are picky, but also not eating enough calories to maintain growth," says Dr. Iskowitz. For those kids, he recommends working with a nutritionist to learn ways to increase the fat, protein and calorie content as part of a healthy diet.

If your child is eating enough, but still not gaining weight, your doctor will want to look for other reasons. "When they're getting enough calories but not gaining weight, we need to consider malabsorption as a possible cause," says Dr. Iskowitz. At that point, you may need to visit a pediatric gastroenterologist to see if the problem is related to a gastrointestinal (GI) condition. Your doctor can perform blood tests, stool analysis, imaging tests or procedures like endoscopy to figure out what's going on.

Some common GI conditions that impact child growth are celiac disease and Crohn's disease. Celiac disease is an autoimmune condition that causes an intolerance to gluten. Children with celiac disease can't absorb certain vitamins and nutrients and may lose weight. Children with Crohn's disease have inflammation in the bowel which leads to malabsorption and weight loss.

In rare cases, a child who's not gaining weight may be burning too many calories. "And I don't mean a kid who just never sits still," says Dr. Iskowitz. "It's when a child has an underlying cardiac or respiratory condition that makes their heart or lungs work too hard."

When To See A Doctor About Your Child's Growth

If your child is underweight and dropping down on the growth chart, talk to your doctor about your concerns. In most cases, once an underlying medical condition affecting growth is diagnosed and treated, they'll start gaining weight.

The sooner you're able to get a diagnosis and begin treatment, the better. Ideally, treatment starts well before puberty so that your child's adolescent growth spurt isn't affected.

"It's okay if your child is trailing along the bottom of the growth chart on their own growth curve," says Dr. Iskowitz. "Most of these kids hit puberty and have a growth spurt that helps them catch up." But it's important that your pediatrician continues assessing your child's growth to make sure they're on track.

Reviewed by Seth Iskowitz, M.D., a pediatric gastroenterologist who sees patients at Henry Ford Medical Center - Royal Oak.