Are You Overtraining or Underfueling?

By Barbara Lewin, RDN, LDN
Sports Nutritionist and Functional Dietitian

If you’re training hard but feeling increasingly tired, you may be wondering whether you’re overtraining or underfueling. Poor recovery, declining energy, and a drop in performance can occur with both, which is why it isn’t always easy to tell the difference.

It’s easy to assume that you’re simply training too much. But training may not be the only problem.

Sometimes athletes aren’t recovering because they aren’t eating enough to support the amount and intensity of training they’re doing.

Overtraining or Underfueling: Why It’s Hard to Tell the Difference

Training places stress on your body. That’s part of how you become stronger and improve performance. But your body also needs adequate nutrition, sleep, and recovery to adapt to that stress.

When that balance breaks down, performance can suffer.

True overtraining syndrome is more than feeling tired after several difficult workouts. It involves a prolonged decline in performance and inadequate recovery and can take considerable time to resolve.

Underfueling occurs when you’re not consuming enough energy to support your training along with your body’s other physiological needs.

Low energy availability can eventually contribute to Relative Energy Deficiency in Sport (RED-S), which can affect both male and female athletes.

Signs of Underfueling in Athletes

Underfueling doesn’t always mean an athlete is deliberately restricting food.

I’ve worked with athletes who eat very healthy diets but simply don’t realize how much energy their training requires.

Others get busy and miss meals, train without eating beforehand, restrict carbohydrates, don’t recover adequately after workouts, or increase their training without increasing their food intake.

Possible warning signs include:

• Persistent fatigue
• Declining performance
• Poor recovery
• Heavy or tired legs
• Frequent soreness
• Irritability or mood changes
• Difficulty concentrating
• Increased injuries or recurrent illness
• Changes in menstrual function in women
• Reduced libido
• Feeling unusually cold
• Trouble sleeping
• Loss of motivation to train

These symptoms don’t automatically mean you’re underfueled, but they’re worth paying attention to.

If you’re frequently starting workouts without enough energy, read What Should I Eat Before a Workout? for practical guidance on pre-workout fueling.

Don’t Overlook Carbohydrate

One of the first things I evaluate when an athlete complains of low energy is carbohydrate intake.

Carbohydrate is an important fuel for moderate- and high-intensity exercise. If you’re training hard while consistently limiting carbohydrate, you may not be adequately replacing muscle glycogen between workouts.

You can consume plenty of protein and still be poorly fueled for your sport.

Timing matters too.

If you’re going into a demanding workout with very little fuel, failing to consume enough carbohydrate during long training sessions, and then eating a protein-heavy recovery meal with very little carbohydrate afterward, your muscles may not fully replenish what they’re using.

Over time, the next workout can begin before you’ve adequately recovered from the last one.

Could You Actually Be Training Too Much?

Absolutely.

Training volume and intensity can increase faster than your body can adapt.

Warning signs that your training and recovery are out of balance can include persistent performance decline, unusual fatigue, mood changes, disturbed sleep, loss of motivation, and an inability to recover despite reducing your training.

But there’s an important point:

Training load and nutrition aren’t separate issues.

The harder you train, the greater your fueling and recovery needs become. An athlete may tolerate a particular training schedule when adequately fueled but struggle with the same schedule when nutrition isn’t keeping pace.

That’s why simply telling an exhausted athlete to “take a few days off” may not address the entire problem.

What Is Low Energy Availability?

Low energy availability occurs when the energy left after exercise isn’t sufficient to adequately support your body’s other physiological functions.

It can happen intentionally, such as when an athlete is aggressively trying to lose weight.

But it can also happen unintentionally.

An endurance athlete may dramatically increase mileage without increasing food intake. A teenage athlete may practice for hours after school without eating enough during the day. An active adult may combine calorie restriction with intense exercise because they’re trying to lose body fat.

And you don’t necessarily have to look underweight to be underfueled.

Recovery Nutrition Matters Too

What happens after training is just as important as what you eat beforehand.

After demanding exercise, your body may need carbohydrate to replenish glycogen, protein to support muscle repair, and fluids and sodium to replace sweat losses.

The amount you need depends on the workout, your body size, how much you sweat, and how quickly you need to perform again.

A protein shake alone isn’t necessarily a complete recovery strategy.

For more guidance, read What to Look for in a Recovery Drink.

What Should You Do If Your Performance Is Declining?

Start by looking at both sides of the equation.

Has your training volume or intensity recently increased?

Then look honestly at your nutrition.

Are you eating enough throughout the day? Are you eating before training? Are you consuming enough carbohydrate? Are you recovering with carbohydrate and protein afterward? Are you replacing fluids and sodium lost through sweat?

Sleep and life stress matter too. Work, travel, family responsibilities, illness, and inadequate sleep all add to the total stress your body is trying to manage.

And don’t assume every case of fatigue is caused by training or nutrition. Persistent or unexplained fatigue may warrant medical evaluation. Depending on the individual, iron status, thyroid function, vitamin deficiencies, illness, medications, and other health issues may need to be considered.

If you’re training regularly but continue to feel exhausted, read Why Athletes Feel Tired Even When They Train Regularly for other factors that may be contributing to low energy.

A Sports Nutritionist’s Take

When an athlete tells me, “I think I’m overtraining,” one of my first questions is:

Are you actually eating enough to support the training you’re doing?

I’ve seen athletes reduce training when part of the problem was inadequate fueling. I’ve also seen athletes try to eat their way through a training schedule that genuinely wasn’t allowing enough recovery.

That’s why I don’t look at training or nutrition in isolation.

I look at the athlete’s food intake, carbohydrate availability, workout schedule, recovery nutrition, hydration, sleep, performance, body composition goals, and overall health.

Sometimes the answer isn’t simply to train less.

It’s to fuel the training you’re already doing better.

The Bottom Line

If you’re wondering whether you’re experiencing overtraining or underfueling, don’t automatically assume that more rest, more caffeine, or another recovery supplement will solve the problem.

Declining performance may be telling you that your training load is too high, your recovery is inadequate, your nutrition isn’t keeping up with your training, or some combination of these factors.

The goal isn’t simply to train harder.

It’s to give your body enough training stimulus and enough fuel and recovery to adapt to it.

References

• Stellingwerff T, et al. Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared Pathways, Symptoms and Complexities. Sports Medicine.
• Meeusen R, et al. Prevention, Diagnosis, and Treatment of the Overtraining Syndrome: Joint Consensus Statement of the European College of Sport Science and the American College of Sports Medicine.

Are You Training Hard but Not Seeing the Results?

If your energy, recovery, or performance has changed, your nutrition may be part of the picture.

Through a Special Introductory Sports Nutrition Consultation, we can look at your training schedule, food intake, fueling, hydration, and recovery and identify areas that may be holding you back.

Schedule your introductory consultation to get started.

About Barbara Lewin

Barbara Lewin, RDN, LDN, is a sports nutritionist and functional dietitian with more than 35 years of experience helping athletes and active adults improve energy, performance, recovery, and long-term health through individualized nutrition strategies.