Do You Need More Calories for Your Workouts?
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How to Know When You Need More Calories for Your Workouts

How to Know When You Need More Calories for Your Workouts
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Updated on December 14, 2025
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Unless you’re an elite athlete, you don’t need to micromanage your workout fuel. Still, even casual exercise burns more calories than resting, so you may need to eat a bit more to support your workouts and recovery.

“In a culture that emphasizes ‘eat less, exercise more,’ a lot of people are scared to eat enough [to support their workouts],” says Zoë Schroeder, RDN, a nutrition coach and certified strength and conditioning specialist based in Tucson, Arizona. But ultimately, underfueling will undermine your goals and slow your recovery.

Here’s how to know when you need more calories to power your exercise routine.

5 Signs You Need More Calories to Support Your Workout

Look out for these common signs that you need more calories, so you can ensure you’re eating enough to support your workout routine.

1. Lasting Soreness

“If you notice that you stay sore for a long time after working out, this is a sign of nutritional inadequacy,” Schroeder says. A little bit of soreness is fine, but if it lasts for days, you might need to up your calorie intake, since proper fueling is key to muscle recovery.

2. Poor Performance and Fatigue

If you notice that you’re not able to go as hard, fast, or heavy in your workouts as you used to, or if you’re constantly fatigued outside of your workouts, Todd Buckingham, PhD, an exercise physiologist and a visiting professor at Grand Valley State University in Allendale, Michigan, says this might be a sign that you’re not eating enough.

3. Illness or Injury

Dr. Buckingham warns that not eating enough calories to support your workouts can lead to illness and injury, as both muscle repair and immune function rely on energy and nutrients from food.

4. Dizziness

Low blood sugar happens when you don’t have enough stored energy. Called hypoglycemia, low blood sugar may result in lightheadedness or dizziness. This is another surefire sign your body needs more calories than you’re taking in.

5. Lost or Irregular Period

Over a long period of time, the combination of exercise and eating too few calories can lead to hypothalamic amenorrhea, a deficiency of the reproductive hormone estrogen. Hypothalamic amenorrhea can lead to lost or irregular periods, as well as irreversible bone loss and an increased risk of cardiovascular disease. If you’re experiencing this symptom, it’s best to speak with your doctor.

Why Does Your Body Burn More Calories During Exercise Than It Does at Rest?

“Our body receives the energy it needs in the form of calories, mainly carbohydrates and fat,” says Buckingham. Carbohydrates break down into glucose and glycogen, while fat breaks down into fatty acids.

 “From there, these glucose, glycogen, and fatty acid molecules get broken down even further into a molecule called adenosine triphosphate (ATP), which is what provides energy.” (Protein breaks down into amino acids, which also break down to ATP, but this process is less efficient and isn’t used to fuel exercise.)

This process, known as metabolism, happens constantly in your body, even when you are stationary, such as while sleeping in bed or working at your desk. But during exercise, Buckingham explains, the rate of ATP production increases to support your muscles (which are doing more work than usual), as well as to regulate your body temperature and sustain your increased heart rate and breathing. The more ATP you produce, the more calories you burn.

How Many Calories Do You Burn During Exercise?

According to the Centers for Disease Control and Prevention (CDC), the average 154-pound person will burn about 280 calories per hour during moderate-intensity exercise like walking, golfing, and casual cycling. The same person would burn between 440 and 590 calories after an hour of vigorous exercise like running, swimming, or circuit weight training.

 For a more accurate estimate on how many calories you burn during a certain activity, you can use a free Physical Activity Calorie Counter, which factors in your body weight, the type of exercise, and the duration.

How Many Calories Do You Need to Support Your Workouts?

To maintain your current weight and keep your energy levels up, you need to eat roughly the same number of calories that you burn each day. For most people who aren’t elite athletes, this happens naturally, without you having to consciously add more food into your day. “Your hunger hormone, ghrelin, ramps up in response to increased exercise as your body's way of telling you to eat more,” Schroeder says.

That means that if you’re doing only moderate-intensity exercise — which, remember, burns about 280 calories per hour — a few times per week, there’s probably no need to intentionally up your calories. But if you exercise at a vigorous intensity (running, circuit training, HIIT), which burns upwards of 500 calories per hour, your ghrelin levels can actually be suppressed post-workout.

So, relying solely on your hunger cues could leave you underfueled, Schroeder says.

“Too much of a calorie deficit can cause individuals to lose muscle mass,” Buckingham says. That’s not ideal, because muscle mass is essential for your health — it enables everyday movement and also supports vital functions like circulating blood and assisting with breathing.

Plus, muscle mass actually helps your body burn more calories overall, even at rest.

If you notice over time that you’re losing weight and you don’t want to, you could try upping your calorie intake by a few hundred calories per day, Buckingham says. One hundred calories is the equivalent of roughly one medium banana or 1 tablespoon of peanut butter.

Tips for Increasing Your Calorie Intake

The good news is that upping your calorie intake is relatively simple. Schroeder recommends adding a snack or two in between meals that contains a balance of protein, carbohydrates, and fat. “Carbohydrates are your body’s main fuel during exercise, so it’s important to replenish them afterwards,” Schroeder says.

“Protein is essential for building and maintaining healthy muscles, and fat is important for vitamin absorption, hormone function, and overall health.” Some easy snacks Schroeder suggests are peanut butter and banana, fruit and yogurt, or hummus and crackers.

Portion size will depend on both your goals and how many calories you’re burning during a workout. If you’re aiming to eat 300 calories, you can get that from one medium banana and 2 tablespoons of peanut butter.

If snacks aren’t your thing, or if you need more calories than snacks can provide, Schroeder recommends adding more healthy fats to your meals, since fat has more than double the calories (9 calories per gram) of protein and carbs (4 calories per gram).

 “Things like avocado, olive oil, and peanut butter can increase calories without adding too much additional volume,” she says. Ultimately, eat healthy, whole foods to feel energized during workouts and throughout the day.

The Takeaway

  • Most casual exercisers don’t need much extra fuel, but certain symptoms can signal you’re not eating enough.
  • Persistent fatigue, dizziness, irritability, or stalled workout progress may indicate a calorie shortfall.
  • Additional balanced snacks or slightly larger meals can support both performance and recovery.
  • If symptoms continue, a healthcare provider or sports dietitian can help you determine your calorie needs.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
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  3. Chen L et al. The Effects of Weight Loss-Related Amenorrhea on Women's Health and the Therapeutic Approaches: A Narrative Review. Annals of Translational Medicine. January 31, 2023.
  4. Holesh JE et al. Physiology, Carbohydrates. StatPearls. May 12, 2023.
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  7. Physical Activity and Your Weight and Health. Centers for Disease Control and Prevention. December 27, 2023.
  8. Ouerghi N et al. Ghrelin Response to Acute and Chronic Exercise: Insights and Implications from a Systematic Review of the Literature. Sports Medicine. December 2021.
  9. Health Lesson: Learning About Muscles. National Institutes of Health. June 2025.
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  11. How Many Calories Should You Eat in a Day? Cleveland Clinic. August 19, 2025.
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Tara Collingwood, RDN

Medical Reviewer

Tara Collingwood, RDN, is a board-certified specialist in sports dietetics, an American College of Sports Medicine–certified personal trainer, and a media spokesperson. As a sports dietitian, she has worked with the U.S. Tennis Association, the Orlando Magic, World Wrestling Entertainment, runDisney, the University of Central Florida, and numerous professional and amateur athletes. Collingwood is the author of Pregnancy Cooking and Nutrition for Dummies and a coauthor of the Flat Belly Cookbook for Dummies.

She appears regularly on national and local TV, and speaks around the world to business teams on how to manage energy physically, emotionally, mentally, and spiritually. She previously served as a national spokesperson for the Academy of Nutrition and Dietetics.

Collingwood double-majored in dietetics as well as nutrition, fitness, and health at Purdue University and earned a master's degree in health promotion from Purdue University. 

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Christine Byrne, MPH, RD, LDN

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Christine Byrne, MPH, RD, LDN, is a registered dietitian providing non-diet, weight-inclusive nutrition counseling to adults struggling with eating disorders, binge eating, orthorexia, chronic dieting, and strong feelings of guilt or shame about food. She founded Ruby Oak Nutrition in 2021 to serve clients and grow a team of anti-diet dietitians. She uses the principles of intuitive eating, Health at Every Size, body respect, and gentle nutrition to help clients recover from disordered thoughts and behaviors and establish a healthier, more peaceful relationship with food and their bodies.

Byrne lives in Raleigh, North Carolina, and sees clients both in person and virtually in several states. As a journalist, she writes about food and nutrition for several national media outlets, including Outside, HuffPost, EatingWell, Self, BuzzFeed, Food Network, Bon Appetit, Health, O, the Oprah Magazine, The Kitchn, Runner's World, and Well+Good.
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