Underweight Gymnast? How to Help Her Gain Weight Safely

What do you do if your gymnast is underweight, has lost her period, has been diagnosed with REDs (relative energy deficiency in sport), or is recovering from an eating disorder? Or what if your pediatrician says she isn’t growing and hands you a list: start a nutrition shake, see an endocrinologist?

An underweight gymnast needs more than a nutrition shake. Nutrition shakes can help, but for a high-level gymnast they’re rarely enough on their own, and they get expensive. In this post, I’ll explain how to read her growth charts, why being “small” isn’t always fine, and practical ways to help her gain weight safely.

By Christina Anderson MS, RDN, CSP, CSSD · Updated October 2026

Why is my gymnast underweight or not growing?

There can be a medical or hormonal reason, and that needs to be checked. But most gymnasts who aren’t growing and developing have what’s called low energy availability. That means she isn’t eating enough to cover her basic energy needs, her growth and development, AND 20+ hours of training a week.

How to read your gymnast’s growth chart

Growth charts tell a story. What’s normal for one gymnast can look totally different for another. What matters is that she tracks consistently along her OWN curve.

Growth charts are split into percentiles (3rd, 10th, 25th, 50th, 75th, 90th and 97th). Dietitians and doctors also use z-scores, from -3 to +3. The 50th percentile is “average,” but it isn’t wrong to be above or below it. We look at her growth history, percentiles, how fast she’s growing, and z-scores together.

This can be normal:

• Her weight has always tracked around the 10th-25th percentile
• Her weight has always tracked around the 80th percentile
• Her weight moves from the 10th-25th percentile up to the 50th-75th after puberty (or after a long-standing energy deficit is finally fixed)

This is NOT normal:

• Crossing major percentile lines downward. For example, a gymnast tracks around the 50th percentile for height and weight from ages 7-10, then as practice hours ramp up and she doesn’t eat enough, both fall to the 10th percentile by 14-15. That’s long-term undernutrition and meets criteria for moderate to severe malnutrition.
• Height that stalls. Poor height gain is a long-term effect of undernutrition. If her height falls below a z-score of -2, that’s considered stunting and needs an endocrine evaluation. There can be medical causes (growth hormone deficiency, thyroid problems, celiac disease), but in a high-level gymnast, the most likely cause is a long-term energy deficit.

A weight at the 75th percentile with height at the 25th can still be normal, though it can also signal something medical, so it’s worth asking her doctor.

Adult height is predicted by her “genetic height potential,” calculated from mom’s and dad’s heights. It is NOT normal for a gymnast to fall short of her predicted height just because “she’s a gymnast.” It’s the same as not getting a period by 15 just because “she’s a gymnast.” (More in Does Gymnastics Stunt Your Growth? and Do Gymnasts Get Periods?)

Why does it matter if a gymnast is underweight?

This sport has idolized the small, thin, “little girl” body for a long time. So why should we care if a gymnast stays small for her age and genetics?

Because it comes with real, long-term consequences. Stunted growth, delayed puberty and poor weight gain are all signs of underfueling, and underfueling affects nearly every system in the body: brain, heart, hormones, periods, bones and muscles. These are all part of REDs, and they threaten both her health and her longevity in the sport.

Can a gymnast look “normal” and still be underfueled?

Absolutely. Many doctors use BMI to judge weight status, but BMI doesn’t account for body composition. You can’t tell if an athlete is underfueled from her weight or BMI alone. You have to look at her growth charts and what normal growth looks like for HER, which can be tricky when she’s been underfueled for years.

Does every small gymnast need to gain weight?

No. REDs is about not eating enough, not about a look. Some gymnasts are genetically smaller, and that’s normal for them. Others are only small because they’re underfueled and their growth is suppressed, and that will hold them back.

Fixing underfueling sometimes leads to needed weight gain, but not always. Fueling properly does NOT mean she’ll gain “a million pounds.” A registered dietitian can help you figure out whether your gymnast is underfueled and, if so, build a plan to fix it.

If your worry is the opposite, that your gymnast has gained weight, see Gymnast Weight Gain: What’s Normal and When to Worry.

How to help an underweight gymnast gain weight

Plan ahead

A high-level gymnast’s schedule is packed: 4+ hour practices that span meals and snacks, privates, PT and conditioning. Two-a-day practices can mean bringing every meal and snack to the gym. A little planning makes this so much easier:

• Use leftovers for lunches
• Prep easy breakfasts, like freezer breakfast sandwiches or yogurt parfaits
• Coordinate with the carpool so she gets a pre-practice snack even when you’re not there

She doesn’t need to live out of Tupperware. The goal is to make fueling the easy choice.

Eat more often

Aim for some food every 2.5-3 hours. That usually looks like 3 meals and 3+ snacks, plus fuel before, during and after practice. Sleeping in late or going 4+ hours between meals makes it hard to fit everything in without her feeling “too full.” Try to get breakfast in by 8 AM.

Make meals and snacks more energy-dense

Use the high-intensity performance plate: about half carbohydrate, a quarter protein, a quarter color, plus fat and dairy. Once she’s meeting her protein needs, carbs and fat are where to add more. A few easy swaps:

• Add healthy fats like nuts, nut butters, olive oil, avocado, ground flax, chia or hemp seeds
• Swap sandwich bread for a bagel, which is denser
• Choose a denser cereal or granola instead of light cereals like Chex or Cheerios
• Add avocado to sandwiches, eggs, soups and smoothies
• Skip “light,” “diet,” sugar-free and low-fat foods (honestly, everyone can skip these)

Watch out for “bulk”

A lot of gymnasts eat “too healthfully,” meaning so much fiber from fruits, veggies and whole grains that they feel full before they’ve met their energy needs. Fiber matters, but she needs room for enough total food. Save drinks for halfway through or the end of the meal, so she doesn’t fill up on a glass of milk before eating.

Frequently asked questions

Get help for your underweight gymnast

Underfueling is so common in gymnastics, and it has major consequences right when it counts: recruiting years and high-level competition.

If you think your gymnast isn’t getting what she needs, start with a visit to her pediatrician or a sports medicine physician who knows REDs and can review her growth and health history. Then take our free Underfueled Gymnast Check. And if you want more than a generic meal plan, The Balanced Gymnast® Program is our 1:1 program, built by a former gymnast, nationally rated NCAA/USAG judge and pediatric sports dietitian who lives and breathes this sport. We build her plan around HER: her growth chart, her training schedule and the foods she actually likes.