Why Athletes Underperform During Stressful Weeks (And How to Fix It)

Picture a high school soccer player on a Tuesday in April. They had three classes before lunch, a history exam in the afternoon, and training at 5pm. By the time they hit the field, they felt flat, mentally sluggish, and a half-step behind. Nothing changed about the training plan itself. Their coach noticed, their parents noticed and they all (athlete included) thought their fitness was slipping.

It wasn't fitness but was actually fuel, and it started hours before warm-ups.

This kind of week is one of the most common things I see with student-athletes, and one of the most misunderstood. When physical training and life stress stack on top of each other with finals week, playoff stretches, showcase weekends and back-to-back competition periods, performance drops in ways that look like a fitness problem but are actually a fueling problem. Understanding why this happens is the first step to fixing it.

Your Brain and Your Muscles Are Running on the Same Fuel

Most athletes plan their nutrition around training. Pre-practice snack, post-training recovery, game-day meals. What gets left out of the equation is everything the brain needs to function through a full day of school, studying, and mental stress before practice even starts.

The brain and the muscles don't have separate fuel supplies. They both run on glucose, and they both pull from the same system. When a student-athlete spends six or seven hours in class, takes an exam, and processes a full day of academic and social demands, that system has been working hard long before they lace up their cleats.

A study published in the journal Physiology and Behavior found that adolescents who skipped breakfast had lower accuracy on cognitive tests and slower processing speed, with effects still present two hours into the morning. When an athlete starts the day underfueled, they're arriving to practice or competition already behind on the resource their brain and body both need.

This doesn't mean adding more stress about eating the perfect food. It means just simply eating intentionally through the full day, not only around training.

What Stress Actually Does Inside the Body

Stress isn't just a mental experience. It triggers a real hormonal response, with the body releasing a hormone called cortisol that's designed to help you respond to pressure. Short-term, that's useful. The problem is when physical stress from training and mental stress run simultaneously for days on end, cortisol stays elevated, and the body's ability to recover slows down.

Research published in Frontiers in Endocrinology studied elite male athletes and found that excessive cognitive activity alongside intense physical training was linked to impaired metabolism and slower recovery. The same research found that carbohydrate intake predicted faster hormonal responses to stress and better explosive performance during exercise, meaning the fuel choices athletes make during these high-demand stretches directly influence how well their body handles the load.

In plain terms: when training and mental stress stack together without the right nutrition to support both, the body stops responding to training the way it should. The athlete does the same work and gets less back. That's not a motivation problem or a fitness problem, it comes back to a fuel distribution problem.

Why Stress Doesn't Cause Junk Food Cravings (But Does Cause Something Worse)

The popular idea is that stress makes athletes reach for junk food. A randomized controlled trial published in the journal Stress followed healthy students through both an exam stress period and a normal period, tracking food preferences, eating habits, and physical activity. The research didn't find a meaningful difference in what people craved between the stress and non-stress periods showing that the junk food craving narrative doesn't hold up.

What the study did find matters more for athletes. During the exam period, subjects became significantly less intentional about eating, moved less, and became more reactive about food. Meal timing broke down, planning disappeared and eating became whatever was available, whenever there was a gap.

That is what actually happens to athletes during high-stress stretches. The enemy isn't willpower or cravings. The structure that was keeping fueling on track collapses and when structure collapses, so does the steady energy supply the body needs to train, compete, and recover.

Why Good Nutrition Doesn't Work When Sleep Gets Cut Short

Sleep is almost always the first thing to get compressed when life gets busy. It feels like the one variable that can flex when everything else can't.

But sleep is when the body actually does the recovery work. It's when muscle tissue gets rebuilt and when the hormones that govern energy and recovery get properly regulated. A review in Sports Medicine found that chronic partial sleep deprivation in athletes can alter how the body metabolizes food and rebuilds muscle, meaning an athlete eating well but sleeping five hours is not getting the same outcome as an athlete eating the same food and sleeping eight.

A review published specifically on elite soccer players identified cognitively demanding activity close to bedtime as a factor that can interfere with sleep quality. An athlete grinding through exam prep until midnight isn't just tired the next morning. They're arriving with a full day of good nutrition that their body didn't have the opportunity to fully process and utillize.

Think of it this way: sleep is the oven. You can put together the right ingredients all day, but if the oven gets turned off early, the meal doesn't finish and you have an undercooked mess. Protecting sleep during high-stress stretches isn't optional so make sure to protect it.

This Is Not the Week to Pull Back on Carbohydrates

There's a common instinct during stressful, busy stretches to eat lighter, simpler, or "cleaner." It feels like the responsible choice when everything else feels out of control. The downside is that this idea usually puts carbohydrates in the crosshairs of what to control and restrict.

But the research points in the opposite direction. The Frontiers in Endocrinology study found that carbohydrate intake predicted faster hormonal responses to stress and better explosive performance during exercise. When athletes are managing combined physical and mental demand without adequate carbohydrates, the body becomes less equipped to handle the stress load and less able to recover between sessions.

Pulling back on carbohydrates during the busiest, most demanding week of the season is removing the primary fuel source exactly when the body needs it most. Keep carbohydrates in, especially in the meals around training. This is not the week to experiment with eating less of them.

What 2% Dehydration Actually Does to Performance

Most athletes think of dehydration as a physical problem: cramping, fatigue, slowing down. Those are real, for sure. What's less appreciated is what dehydration does to the brain, and the threshold at which it starts.

A randomized crossover study in the International Journal of Sports Physiology and Performance tested competitive athletes at three different hydration levels and found that just a 2% loss in body weight from fluid can impair reaction speed and reduce technical performance compared to the fully hydrated condition. For most high school athletes, 2% is roughly three pounds of fluid, an amount that gets lost quietly during a day when intentional habits have fallen apart.

During high-stress training weeks, hydration is one of the first things to slip below maintenance. Schedules get disrupted, water bottles get left behind, and the intentional drinking habits that were working during normal weeks disappear. The result shows up on the field as slower decision making and delayed reactions, and most athletes and coaches blame fitness.

The fix is straightforward: drink on a schedule rather than waiting for thirst. One bottle before school, one at lunch, one before practice, one after. Don't rely on thirst to remind you. By the time thirst arrives, you're already behind.

What to Actually Do This Week

The goal during a high-stress training period isn't to change everything. It's to protect the things that were already working. Here's what that looks like in practice:

Keep carbohydrates in place around training sessions. Don't cut them out or reduce them because the week feels like a good time to clean things up. Your body needs them more, not less, when you're also managing mental stress.

Eat on a schedule, not on hunger. Stress dampens hunger signals, which means waiting until you feel hungry will leave you running behind. Set meal and snack times and treat them as seriously as you'd treat practice.

Protect sleep. Set a hard stop for studying and screen time at least 30 minutes before bed. Sleep is where your nutrition does its job. Cutting it short cuts the results.

Hydrate intentionally. One bottle at four predictable moments in your day. Lock that in for a fantastic starting point.

Look at that list and find the one area that feels most off right now. Focus therefor seven days. You don't need to fix everything at once. Protect the one thing that's slipping most.

Frequently Asked Questions

Why do I as an athlete feel flat during stressful weeks even though training hasn't changed?

The most common reason is that the body is managing two high-demand systems at once without the fuel strategy to support both. Physical training and mental stress both draw from the same energy system, and when the two stack together without adjustments to nutrition and sleep, recovery slows down, hormonal function changes, and the body stops responding to training the way it normally would. This isn't a fitness problem but a fuel problem, and it's fixable.

Should athletes eat more food during high-stress training periods?

Not necessarily more in terms of quantity, but more intentionally in terms of timing and structure. The most common issue isn't total food intake, it's that the structure around eating breaks down with meals getting skipped or delayed, and carbohydrates getting reduced at the exact moment the body needs them most. The goal is to protect the fueling structure that was already working, not to add volume for the sake of it. That said, if an athlete is noticeably eating less during stressful stretches, restoring their normal intake is the first and most important step.

Does stress really make athletes crave junk food?

The research suggests it doesn't, at least not in the way it's commonly described. A randomized controlled trial that tracked students through exam periods found no meaningful difference in food preferences under stress compared to non-stressful periods. What stress did change was intentionality around eating where people became more reactive and less planned, eating whatever was available rather than what they'd normally choose. For athletes, the real risk during high-stress weeks isn't junk food cravings. It's the collapse of the structure that keeps fueling on track.

Can a sports dietitian help my athlete with nutrition during high-stress training periods?

This is one of the most common things we address at Rise Nutrition. Working with a sports dietitian means building a fueling plan that accounts for what the season actually looks like, including the weeks where school, competition, and training all collide. Rather than applying general nutrition advice, we build around the athlete's specific schedule, training load, and the moments where structure tends to break down. If high-stress weeks are a recurring problem for your athlete, a Game Plan Call is a good place to start.

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If you want to know whether iron could be a factor in your athlete's performance this season, the best first step is a conversation. Book a free15-minute Game Plan Call and we'll work through what the data says and what makes sense to do next.

Jay Short, MS, RD, CSSD is a Registered Dietitian and Board Certified Specialist in Sports Dietetics, and co-owner of Rise Nutrition, specializing in sports dietetics for competitive athletes. He works with US Soccer (all 27 teams), the Columbus Blue Jackets (NHL), and athletes across MLS, collegiate, and club programs.

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References

1. Cooper SB, Bandelow S, Nevill ME. Breakfast consumption and cognitive function in adolescent schoolchildren. Physiology & Behavior. 2011;103(5):431–9. https://pubmed.ncbi.nlm.nih.gov/21439306/
2. Cadegiani FA, Kater CE. Eating, sleep, and social patterns as independent predictors of clinical, metabolic, and biochemical behaviors among elite male athletes: The     EROS-PREDICTORS Study. Frontiers in Endocrinology. 2020;11:414. https://pubmed.ncbi.nlm.nih.gov/32670198/
3. Berg Schmidt J, Johanneson Bertolt C, Sjödin A, Ackermann F, Vibeke Schmedes A, Lynge Thomsen H, Marie Juncher A, Hjorth MF. Does stress affect food preferences? A     randomized controlled trial investigating the effect of examination stress on measures of food preferences and obesogenic behavior. Stress. 2018;21(6):556–563. https://pubmed.ncbi.nlm.nih.gov/30388041/
4. Halson SL. Sleep in elite athletes and nutritional interventions to enhance sleep. Sports Medicine. 2014;44 Suppl 1:S13–23. https://pubmed.ncbi.nlm.nih.gov/24791913/
5. Nédélec M, Halson S, Delecroix B, Abaidia AE, Ahmaidi S, Dupont G. Sleep hygiene and recovery strategies in elite soccer players. Sports Medicine. 2015;45(11):1547–59.     https://pubmed.ncbi.nlm.nih.gov/26275673/
6. Zheng AC, He CS, Lu CC, Hung BL, Chou KM, Fang SH. The cognitive function and taekwondo-specific kick performance of taekwondo athletes at different hydration statuses. International Journal of Sports Physiology and Performance. 2024;19(7):637–644. https://pubmed.ncbi.nlm.nih.gov/38702046/