You can read something new every day about the current obesity epidemic. In fact, the percentage of overweight Americans has never been higher. But another, sometimes overlooked weight problem also exists: children who are underweight for their age or size.

What causes this problem and, when it happens, how do healthcare providers get families back on track and help their children gain weight in a healthy way? Pediatric registered dietitian, Jennifer Willoughby answers common questions.

Q: What qualifies as ‘underweight’ for a child?

A: In general, a child is underweight if he or she is in the bottom 5th percentile for weight compared to their height. Underweight is not only classified compared to other children their age, but to their height as we clinically look for a child to be proportionate.

The way pediatricians and dietitians monitor children is on a weight-to-length measurement for children from birth to age 2.  After age 2, we use the Centers for Disease Control growth charts to look at weight, height and BMI (body mass index) for age. BMI for this age range compares a child’s weight to their height. A BMI for age less than the 5th percentile indicates a child is underweight.

Q: How can I tell if my child is underweight?

A: There are several signs that parents should watch for:

• Every kid has his own optimal weight, but if your child’s weight percentile declines on the growth charts at annual pediatrician visits, that’s cause for concern.
• At home, keep an eye on how clothes fit your child. If a younger child doesn’t begin to outgrow her clothes over several months, you should meet with your pediatrician.
• At bath time, or at the swimming pool or beach during summer months, watch to see whether you can see your child’s ribs. Ribs that stick out or are prominently visible are a sign that your child may be underweight.

Q: Are there medical issues that cause this problem?

A: Children born prematurely are often underweight because their growth needs to catch up with peers, but a common reason that older children are underweight is inadequate food intake.

This may or may not be a result of picky eating. There are also several medical issues that can suppress appetite or block nutrient absorption. These include:

• Medications, such as those used in attention deficit-hyperactivity disorder (ADHD), which can suppress appetite.
• Food allergies, which can make getting enough calories a challenge — and the more food allergies, the greater the challenge.
• Hormonal or digestive problems or other issues of inadequate nutrient absorption that can sometimes keep children from gaining weight as they grow.

Q: Are there daily situations that might keep my child from maintaining a healthy diet?

A: When a pediatrician finds that your child is underweight, he or she may schedule a one-day consultation with a dietitian. The goal is to rule out poor food intake as the issue, and if so, the dietitian can offer recommendations.

You’ll usually be guided to keep a food record that examines your child’s eating habits. The dietitian will also look at other possibilities:

• For daycare-aged kids, some centers are better than others at documenting that your child is consuming enough calories during the day.
• For older kids, sports and other school activities often create a hectic schedule where kids just don’t eat enough. If active, they also have a higher caloric need and may not be making up for it.
• Children who stay with multiple households due to their parents’ separation or divorce may sometimes miss meals without either parent knowing.

Q: What eating habits should children avoid?

A: One of the most common pitfalls is “grazing” or excessive snacking. Families should set meal and snack times so that the child has time to get hungry before sitting down to a proper, nutritionally balanced dinner. “Grazing” will fill the child up on foods with low energy density.

Snacks are certainly OK and encouraged, but children should eat them at the table — not mindlessly in front of the television or computer screen.

In general, avoid fruit juices, especially those with added sugar. Juices and other sugary beverages will fill kids up without providing them with any energy, fat or protein.

Protein powders aren’t recommended because even underweight kids still seem to get enough protein in their diet (and the powders don’t provide a balance of nutrients needed for weight gain).

Q: How can families help children gain weight in a healthy way?

A: Believe it or not, the goal is to incorporate more fats into the child’s diet — not just any fats like saturated fats from meats, but healthy fats like those from oils and nut butters. Here are some suggestions:

• Add peanut butter. For example, encourage kids who like raw fruits and vegetables to eat celery sticks or apple slices with peanut butter.
• Sneak in healthy oils. It is also beneficial to sneak in some olive oil or other heart healthy oils by adding it to foods, which can help even the pickiest eaters.
• Try oral supplements. Ask to speak with a registered dietitian regarding the appropriate oral supplement for your child.

The overall goal is to instill sustainable, healthy eating habits. That’s why it’s important to meet with a dietitian who will also help monitor your child’s progress and offer tips and recipes.

Q: What if my family has special dietary needs or beliefs?

A: Dietitians work closely with parents and families to aid their understanding of why food intake is inadequate.

Dietitians focus on working one-on-one with families to help children gain weight in a way that is consistent with the family’s dietary preferences. They can work with all sorts of preferences and varieties of food, including organic foods, whole foods, vegan diets, or diets influenced by religious or cultural beliefs.