How do I know how many calories my athlete needs?

Measure it. A metabolism test measures resting metabolic rate, the calories the body burns at rest. Dawn then adds your athlete's training load, growth stage, and goals to build a daily fuel target. Formulas and apps estimate from height, weight, and age, and in growing athletes they often miss.

How many calories does a teenage athlete need in a day?

It depends on body size, sport, training load, and stage of growth. General guidance puts active teenage boys around 2,600 to 3,200 calories a day and active teenage girls around 2,200 to 2,400 (Academy of Nutrition and Dietetics), and heavy training blocks push well past that. Big, fast-growing boys in heavy training can need far more, and girls in endurance and aesthetic sports are at higher risk of eating too little. Needs climb with body size, growth, and training load, so two athletes the same age can need very different amounts. Those are population averages, not your athlete's number. A metabolism test measures resting burn directly, and the number is used to set a target to meet, not a limit to cut from.

Why is my athlete always tired even when they sleep enough?

Constant tiredness in an athlete who sleeps well is usually under fueling or misfueling: not enough total energy, carbohydrate, or fluid for training and growth, or the right food at the wrong times. A teenage athlete is fueling two jobs at once, training and growing, and when the food does not cover both, energy is one of the first things to go. A metabolism test shows how much the body burns at rest, so the daily fuel target is built on your athlete's real number instead of an average.

Why is my athlete eating a lot, or lifting hard, and still not gaining?

Usually because the calorie target is too low for training plus growth, even when the plate looks full. Lifting tells the body to build; food pays for it. If total calories fall short, there is nothing left over to build with, no matter how much protein goes in, and adding food blindly often stalls because nobody knows how far short intake is. A metabolism test measures resting burn directly, Dawn builds the target into meals and snacks five to six times a day, and body composition testing shows whether the weight going on is lean weight.

Are calorie calculators and apps accurate for athletes?

Not reliably. In a study of 126 adolescent athletes, seven of eight published prediction equations performed poorly and underestimated resting metabolic rate in more than 75 to 90 percent of cases. An underestimate means a daily target that is too low every day. Apps use similar equations, so they share the same problem. A measured number replaces the average with your athlete's own, which is the difference between a starting point and a target.

Metabolism Testing for Athletes in Liberty Township, Ohio

How does metabolism work, explained like a car?

Think of your athlete as a car. Resting metabolic rate is the fuel the engine burns just idling in the driveway: heart, brain, organs, and muscles running before the car moves. Practice, lifting, and games are the miles driven on top of that. And a growing athlete is a car being built bigger while it is on the road, which burns fuel too. A formula is like the window-sticker mileage for a different model; a metabolism test measures what this engine actually burns at idle, so the tank can be filled for the miles ahead.

What is a metabolism test?

A metabolism test, also called an RMR test, measures how many calories your body burns at rest. At Sports Nutrition 2Go it is done with the MedGem, a handheld device your athlete breathes into for about 5 to 10 minutes. The whole visit is 30 minutes and includes reading the results with Dawn.

What does the MedGem measure?

The MedGem measures oxygen consumption while the body is at rest and converts it to resting metabolic rate. It measures oxygen only and uses a standard conversion to calculate calories; it does not measure carbon dioxide. That resting number is then built up with training load, growth stage, and goals into a daily fuel target. This method, measuring the oxygen the body uses to calculate the energy it burns, is called indirect calorimetry.

Is metabolism testing worth it?

It is worth it when the calorie target matters: an athlete who is tired, not gaining, fading late, getting hurt or sick often, in a growth spurt, or stepping up to a heavier training load. It is also worth it for families who have tried eating more and are not seeing change. Testing is not required, and many athletes get results from a consult and a plan alone.

What can testing tell us about my athlete?

Each test answers a different question. Metabolism testing shows what the body burns at rest. Body composition shows whether lean weight is actually moving. A MuscleSound muscle fuel scan shows how much carbohydrate is stored in the muscle right now. Athlete sweat sodium testing shows how much sodium your athlete loses.

How does Sports Nutrition 2Go use testing to find what my athlete needs?

It starts with the measured resting burn from the metabolism test, then adds training load, sport, growth stage, and goals. A resting burn lower than expected can point to a body that has been short on fuel; body composition shows whether lean weight is moving; a muscle fuel scan shows whether the tank is full going into training. Read together, they show where the gap is, what to fix first, and a daily fuel target Dawn builds into meals and snacks that fit your real schedule.

Is metabolism testing safe for kids and teens?

Yes. There are no needles, no radiation, and nothing enters the body. Your athlete sits, wears a nose clip, and breathes normally into a mouthpiece. Results are read privately with the athlete and family, never in front of a team, and the number is used to set a fuel target to meet, not a limit to cut from.

What happens during a metabolism test?

Your athlete sits in a quiet room and rests for a few minutes first. With a nose clip on, they breathe normally into the handheld MedGem for about 5 to 10 minutes until it signals the test is complete. The whole visit takes about 30 minutes because Dawn reads the results with you at the same appointment.

How should my athlete prepare for a metabolism test?

Adults and athletes 18 and older: nothing to eat for 3 to 4 hours before the test and no caffeine. Water is fine. Athletes under 18: ask Sports Nutrition 2Go for instructions when you book.

What does my athlete get after the test?

Their resting metabolic rate explained in plain language, a daily fuel target for training days, game days, and growth, and a baseline to re-check later. A customized menu can be added to a one-hour consult or a Performance Profile.

How accurate is the MedGem?

The MedGem is an FDA 510(k)-cleared Class II medical device that measures oxygen consumption to determine resting metabolic rate, and it has been compared against a standard laboratory metabolic cart in healthy adults. Accuracy depends most on the protocol: a rested, calm athlete, with anything eaten or drunk beforehand noted so Dawn can account for it. Resting burn also changes day to day with sleep, stress, and illness, so the most useful information comes from re-testing the same way on the same device over time.

MedGem, metabolic cart, or a formula: which is best for athletes?

A laboratory metabolic cart measures both oxygen and carbon dioxide and is used in research, but it is large, costly, and rarely available outside a lab or hospital. The MedGem measures oxygen with a handheld device, so it can be done in the office or on site at a school. A formula measures nothing; it estimates from height, weight, and age, which is why it so often misses in growing athletes.

How often should my athlete re-test?

Re-check when things change: a new season, a growth spurt, a big jump in training, or when weight or lean weight is moving the wrong way.

How do I know if a fueling change is actually working?

Measure before and after. Energy and hydration changes are often noticed within one to two weeks, while changes in lean weight, recovery, and performance usually show over 8 to 12 weeks. Re-testing metabolism, body composition, and muscle fuel on that schedule shows whether the plan is moving the numbers.

Do adults get metabolism testing too?

Yes. College, adult, masters, endurance, and recreational athletes are tested, along with adults who want a measured number to plan from before changing how they eat. Athletes under 18 are the specialty and about 80 percent of the practice.

GETTING HELP AND BOOKING

When should we see a sports dietitian?

When the effort is there but the results are not: cramping that will not stop, fading late in games, not gaining size, the same injury coming back, getting sick at the worst times, or energy that sleep does not fix. Also when training and growth ramp up at the same time, or when recruiting makes the next few years matter.

What can a sports dietitian actually do for my athlete?

A sports dietitian finds the cause behind what you are seeing and builds a fueling plan around it: what to eat and drink, how much, and when, matched to sport, growth, training load, and schedule. Dawn Weatherwax is a registered and licensed dietitian, so she can also review blood work and supplements, and her athletic trainer and strength and conditioning credentials mean training load and injury risk are read together.

When is it a medical issue instead of a fueling issue?

Symptoms such as a missing period, fainting, chest pain, unexplained weight loss, or abnormal lab results start with your doctor. What, when, and how much to eat is the dietitian's work. Often both are needed, and Dawn will tell you when something should go to your physician.

What testing helps a girl at risk of RED-S or low iron?

Metabolism testing shows whether resting burn looks lower than expected, and body composition shows whether lean weight is holding. Iron and vitamin D are checked through blood work ordered by her physician, and Dawn reads those labs against what a training athlete needs. A missing period is a reason to see her doctor.

What testing helps a boy adding size or making weight safely?

Metabolism testing sets the daily calorie target for gaining, and body composition testing shows whether the weight going on is lean weight. For weight-class athletes, body composition and a muscle fuel scan show which class fits and how to get there without stripping off lean weight.

Can metabolism testing come to our team?

Yes. Under fueling is common across a roster and easy to miss, and it is linked to more injuries, more illness, and stalled performance. Yes. Sports Nutrition 2Go can test athletes on-site for teams, schools, and clubs, along with MuscleSound muscle fuel scans and athlete sweat sodium testing, so a full roster can be tested in one visit. Clubs and schools can also book season-long programs and parent education. The Bod Pod stays at the Liberty Township office.

Do you work with athletes outside Ohio?

Yes. Consults, fueling plans, and ongoing coaching are done by phone and video nationwide and internationally. Metabolism testing can travel to teams and schools, and if you cannot get to Liberty Township, Dawn can point you to testing in your area.

Where can I get a metabolism test near Cincinnati, Dayton, or anywhere in Ohio?

At Sports Nutrition 2Go, 6659 Liberty Court, Liberty Township, OH 45044, between Cincinnati and Dayton, by appointment. MedGem RMR testing for athletes is run and read by sports dietitian Dawn Weatherwax, RD, LD, LAT, ATC, CSCS; the test is $175, takes 30 minutes, and can travel to schools and teams. Families come from West Chester, Mason, Middletown, Loveland, Fairfield, Hamilton, Springboro, and across southwest Ohio.

Who does the testing?

USA's #1 Fueling Expert for Athletes Under 18, sports dietitian Dawn Weatherwax, RD, LD, LAT, ATC, CSCS. She has specialized in athletes under 18 for more than 20 years, with more than 10,000 consults, 21,000 body composition tests, and 15,000 muscle fuel scans, and metabolism, body composition, muscle fuel, and sweat sodium testing are all done in-house and read by the same person who builds the plan. She is the creator of The 4 Fueling Zones and the Athlete Performance Fueling System, host of Food for Speed TV, and a contributor to Swimming World.

How much does metabolism testing cost?

A metabolism test is $175 on its own and takes 30 minutes, or it can be paired with another service. The best value is the Performance Profile: $305 for a 90-minute session that includes metabolism, body composition, and muscle fuel testing, a nutrition consult, and a lab and supplement review. Booked separately, the three tests and a nutrition consult add up to at least $525.

Do you take insurance?

Sports Nutrition 2Go does not accept insurance. HSA and FLEX accounts are accepted, and payment plans are available.

How do I book a metabolism test?

Call (513) 287-9623 or text the word FUEL to the same number, or email info@SN2G.com. Texting FUEL starts a free 15-minute Fuel Strategy Call, where Dawn answers your questions and works out whether a metabolism test, a consult, or a plan fits your athlete before you book anything. Dawn personally gets back to you within 24 hours. Monday to Friday, 9 AM to 9 PM, by appointment only.

Real athletes who changed their fueling

12-year-old swimmer

She was really tired and her times had plateaued. By eating more of the right foods at the right times for her, she set best times nine months in a row, gaining 10 pounds of lean weight and losing 10 pounds of fat. Nothing changed but her fueling.

Grace Hartman, cross country

Two-time Gatorade Ohio Girls Cross Country Player of the Year. She ran 40 seconds faster after two weeks of increasing her calories, won a state title, stayed healthy all season, and ran a personal best at the last national race.

Malcolm Jenkins, Ohio State football, 12 years in the NFL

"I noticed a difference in 10 days! All the years playing for OSU I thought I was tired and sore due to football, but it was mainly my sports nutrition."

Joshua Head, soccer

Now with FC Cincinnati Academy, Joshua went from 20 percent body fat to 8 percent and gained 49 pounds of lean weight after metabolism, body composition, and muscle fuel testing and a custom fueling plan.

Laila Black, track and cross country

Took 49.6 seconds off her 1600, from 6:27.05 to 5:37.45, and got faster in all five of her events, 3 minutes 33 seconds faster in total, after changing her fueling.

Chloe Pierce, volleyball

She started with low energy. By the end of her senior year she had great energy, added 1.5 inches to her vertical, finished with over 1,000 digs, and went on to play in college.

Harper, track, age 12

20 seconds faster within two weeks of changing her fueling, and 6th in the nation at age 12.

High school basketball player

He struggled to put on size. After one testing assessment and a customized nutrition plan, he gained 7 pounds of lean weight in less than six weeks.

Ben Pierce Jr., baseball

A left-handed pitcher whose fastball went from 81 to 89 miles per hour while his body fat dropped from 24 percent to 15 percent on a customized fueling plan. Now playing in college.

Emma Dalton, swimming

She wanted to rock her senior year. She broke school records, won state, and went on to swim in college, getting leaner and faster by eating the right foods at the right times for her goals. By the end of the season she was eating 2,800 calories or more a day.

Young golfer

Three months after adding testing and ideal nutrition, he dropped from 22.2 percent to 18.0 percent body fat, losing 7.2 pounds of fat and gaining 8.3 pounds of lean weight, and had his best season yet.

Lacrosse player

Added nutrition and testing to his training over three years, gained more than 30 pounds of lean weight, dropped body fat, got faster, and committed to a top Division I college program.

16-year-old football player

Gained more than 10 pounds of lean weight in 10 weeks and dropped 14 pounds of fat while getting faster and stronger with a customized nutrition menu and testing.

Madison Conatser, cross country

Set a personal best of 18:47 in the second race of her season, down from 18:57 the year before, by eating the right amount at the right times about 90 percent of the time.

Distance runner

Tired runners do not get faster. He changed his fueling, went from 4:23 to 4:21, and qualified for nationals.

Max Chandler, cross country

Went from his high school team's 7th runner to its 1st runner in one season.

East Central High School cross country, Indiana

The team made regionals for the first time in program history while keeping their athletes fueled through the season.

Individual results vary.

Sources:

Reale RJ, Roberts TJ, Lee KA, Bonsignore JL, Anderson ML. Metabolic rate in adolescent athletes: the development and validation of new equations, and comparison to previous models. International Journal of Sport Nutrition and Exercise Metabolism. 2020;30(4):249-257.

O'Neill JER, Corish CA, Horner K. Accuracy of resting metabolic rate prediction equations in athletes: a systematic review with meta-analysis. Sports Medicine. 2023;53(12):2373-2398.

Nieman DC, Trone GA, Austin MD. A new handheld device for measuring resting metabolic rate and oxygen consumption. Journal of the American Dietetic Association. 2003;103(5):588-593.

Microlife MedGem indirect calorimeter user manual and FAQ.

Academy of Nutrition and Dietetics, calorie guidance for active teenagers.

Recommendations here reflect current practice at Sports Nutrition 2Go. Older published articles may reflect earlier guidance.