Worried About Your Underweight Child? Here’s What Helped Mine.

Inside: If you have an underweight child (or a child who takes medication that affects her appetite), here are 10 tips to help you!

What I've Learned About Feeding An Underweight Kid
Presentation makes a big difference when it comes to food!

When my son was in middle school, we were told by the pediatrician that he was borderline underweight.

He’d been battling stomachaches, and there were many nights when he didn’t feel well enough to eat dinner. While everyone around me seemed to be going on and on about the vast quantities of food their tweens and teens were inhaling, I was asking my child if he’d eaten at all–and clearing away his barely-touched plates.

As a registered dietitian and a mom, I was worried

As parents, we all have an instinctive drive to feed and sustain our kids. When something gets in the way of that–whether it’s picky eating or an illness–it’s hard not to stress.

A few doctor’s visits, a trip to a specialist, some lifestyle changes, and many months later, I’m happy to report that his stomach pain is mostly a thing of the past. But that year taught me a lot about the day-to-day practicalities and challenges of feeding a child who needs to gain weight but doesn’t have much of an appetite. 

I’ve heard from some of you that you have a child who is underweight and/or takes medicine that affects appetite and weight. So I wanted to share some lessons I’ve learned about feeding an underweight child and encouraging weight gain in a healthy way.

10 Tips for Healthy Weight Gain

1. It’s not just about calories

It would be easy to throw a bunch of cookies and potato chips at the issue. But I’m a dietitian, so I can’t help but focus on the quality of those calories too.

As children are growing and developing, they need nutrients like iron, protein, and calcium–and just as important, they’re forming ideas and habits around food and eating that can stretch into adulthood.

So during the year of stomachaches, I kept serving healthy meals and made sure most snacks were calorie-dense but also nutrient-dense, which meant things like nuts, dried fruit, and cheese sticks. That being said, I also didn’t worry about daily dessert (I still don’t) or the liberal use of real butter (still don’t).

Apples with Chocolate chip Peanut Butter
Peanut butter is rich in both calories and good nutrients.

2. Presentation Presentation Presentation

I firmly believe that when it comes to kids and food, presentation is key. But this is especially true for kids who have small appetites.

I tried to make those healthy, nutrient-rich foods look especially appetizing, whether it was putting yogurt and berries in a fancy glass or pulling together an after-school Snack Platter. I also used white plates for his meals–which, as I know from doing food photography, make food really pop. These were small and easy things for me to do but made a difference for him.

White plates can work magic!

3. Switch your dairy

Switching from low-fat to full-fat dairy products like whole milk and full-fat yogurts is a great way to snag a lot of nutrients and extra calories (read about why full-fat milk shouldn’t be feared: Is Whole Milk Healthier?).

I buy full-fat cheese and pick up tubs of full-fat yogurt and individual cups for lunch boxes. (Though low-fat and non-fat yogurts still dominate shelves, more companies are making full-fat versions too. My kids like full-fat cups made by Dannon, Stonyfield, and Annie’s.) I also buy a half-gallon of whole chocolate milk every week.

Is Whole Milk Healthier?
Full-fat dairy is your friend.

4. Focus on favorites

You know I’m all about making just one meal for the whole family (read The Dinnertime Rule That Will Change Your Life). But when my son’s appetite was down, I did make sure to regularly serve meals I knew he especially enjoyed–and tried not to show my disappointment if he didn’t want to eat that evening. Some of his favorites are this Whole Wheat Chicken Pot Pie and this Whole Wheat Spaghetti Carbonara.

Whole Wheat Chicken Pot Pie
Serve small portions of favorites (and be patient).

5. Watch out for drinks

Yes, hydration is important. But some kids can fill up on drinks like juice and milk and not have room left for actual food at mealtime. I tried to pour him a smaller drink with meals, obviously allowing for refills! Read: What Are The Best Healthy Drinks For Kids?

Small glass of orange juice
Too much juice (or milk) can dull the appetite for food.

6. Don’t fear fat

I came of age in the 80s and 90s, when we were taught to fear fat. But it’s high time to let that go–especially where underweight kids are concerned. That’s because fat is the most calorie-dense nutrient, and can go a long way in helping children get enough calories.

Here are some ways to add it in: Toss pasta in olive oil before adding other sauce, butter bread under peanut butter on PBJs, sprinkle cheese on pastas and rice dishes, and add avocado to a smoothie (sounds weird, but it adds a great creaminess!). 

Avocado, granola, and nut butter are all healthy, calorie-dense foods.

7. Compromise

In my ideal world, my son would be craving quinoa salads and butternut squash soup. In the real world, he’s a regular kid who likes chicken wings and soda. Thankfully there is a middle ground with foods we both feel good about (like whole wheat spaghetti and meatballs, guacamole and chips, and Caesar salad), and there’s wiggle room too (like the beef jerky he loves).

8. Serve small portions

At mealtime, either had my son serve himself or gave him very small portions (with seconds and thirds readily available). I learned this from my rotation through a nursing home while in school to become a dietitian: Large portions are overwhelming and unappealing to someone with a small appetite, but small portions may actually encourage that person to eat more. That was also my approach when packing his lunch (read How Much Should You Pack In Your Child’s Lunch Box?).

Serving nut butter alongside apple slices increases calories (and nutrients).

9. Include calorie-dense foods

There are certain foods that are both calorie-dense AND nutrient-dense–and they can help your child get more calories, as well as more nutrients. I tried to include some of these at meal and snack times:

  • Dried fruit
  • Nut butters (such as peanut butter and almond butter) and seed butters (such as sunflower butter)
  • Nuts and seeds
  • Full-fat milk and yogurt
  • Cheese
  • Avocados 
  • Trail mix and granola
  • Salmon
  • Beef
Double Chocolate Almond Granola -- Real Mom Nutrition
This Double Chocolate Granola makes a fun breakfast or snack.

10. Avoid Pressure

Nagging kids about food is never a good idea. It was tempting to grill my son about what he’d eaten that day or sigh with dismay when he barely ate his packed lunch. But I tried to have the same relaxed, accepting attitude I recommend all parents strive for at the table (full disclosure: I didn’t always succeed!). I also tried to have faith that things would get better. (And luckily they did!)

FAQ About Underweight Kids

What can cause poor weight gain in kids?

Poor weight gain can be caused by things like medications that lower appetite (such as some ADHD medicines), food allergies that limit the number of “safe” foods they can eat, illness, and and certain medical issues. Stress and anxiety can also cause poor appetite.

Protein powder and protein shake
Protein powder is easy–but might not be needed.

Can protein powders be helpful for underweight kids?

Maybe. Most kids get enough protein, since many foods beyond meat contain it, including milk, cheese, and grains like pasta. But powders can be an easy way to get protein, especially for picky eaters who are underweight.

Protein powder can be pricey and contain a lot of extra ingredients, like artificial sweeteners or even herbal supplements. So while a protein shake once in a while is fine, you can also make your own protein-rich shakes from regular ingredients. Here’s are recipes for a Peanut Butter Protein Shake and Protein Pancakes that don’t contain any protein powder.

How do I know if my child is underweight?

Your child’s doctor is the best resource for this, because they track your child’s weight and height on a growth chart at each visit. 

Technically, underweight means below the 5th percentile for BMI (Body Mass Index) for age, gender, and height. But BMI isn’t a perfect measure and doesn’t account for things like frame size and muscle.

Keep in mind that some children are just naturally thin, and a “skinny kid” isn’t necessarily something to worry about. A sudden growth spurt where a child shoots up in height first before gaining weight can also look like underweight.

What’s more important is your child’s growth pattern: Is their weight increasing predictably on their growth curve, or is it flattening out or falling off? Has their weight suddenly dropped? Are they having a decreased appetite or issues with eating?

What foods are “empty” calories?

This term is typically used to describe foods that don’t contain many nutrients–things like pretzels and candy come to mind. Yes, nutrients are important. But in my opinion, a well-balanced diet also contains some foods that are eaten simply for “fun”. (And things like cookies, ice cream, and chips do provide calories too.)

Does my underweight child need a multi-vitamin?

Maybe. Talk to your child’s pediatric or pediatric dietitian to see if your child is getting enough of a variety of foods to supply the nutrients they need. Underweight kids who are very picky eaters may especially benefit from a supplement.

Where can I go for more help?

Ask your child’s doctor about a referral to a pediatric dietitian, who can help guide you. You can also call a local children’s hospital and ask whether they have pediatric dietitians who do outpatient counseling.

Do you have any experience feeding an underweight child–if so, what works/worked best for you?

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