Summer Training and Under-Fueling: Why You Feel Slower When You're Working Harder

Short answer: hard summer training quietly turns your appetite down, so you end up eating less right when your body needs the most fuel. It happens by accident, it builds over a few weeks, and the fix tends to center around when you eat, not simply eating more.

You are training more this summer than you have all year. Camp, two-a-days, extra sessions on top of club training. So why do you feel slower instead of sharper? Flat in sessions you used to breeze through, and you cannot point to a single thing you did wrong.

Here is what is usually going on, and it is not a discipline problem. When your training jumps for the summer and nothing in your day forces you to notice, your eating quietly drifts down at the exact moment your body needs more. There is no single skipped meal to blame. No bad day stands out. It is a slow drain, and by the time you feel it, you have already been running low for weeks. The short version: you are not eating enough to match the work, and it happened by accident.

Once you can see how it happens, the fix is simple. This is one of the most fixable problems I deal with, and almost none of it means eating more by force or counting a single thing.

Why Hard Training Kills Your Appetite

Most athletes never get told this part. A hard session, especially in summer heat, turns your hunger down for up to a few hours afterward. That is normal. Your body does it on purpose. A 2023 review in the journal Appetite by Thackray and Stensel, found just that with hard exercise quieting hunger for awhile, and then it settles back to normal within a few hours.

Now the part that actually matters. That same review pointed out something easy to miss: when you burn a lot of energy through training, your body does not later make you eat it back. That is the opposite of what happens when you skip meals on purpose. Cut food deliberately and your hunger ramps up fast and fights you until you eat. Burn the same energy in a hard session and your body stays quiet about it. Your hunger lags behind the work, and it never sends you the signal.

So you finish training, you are not hungry, you skip the snack, you eat alight lunch, and the fuel just goes missing. No struggle or intentional decision.That is what makes it accidental. You did not get less disciplined, you just stopped feeding the work, and you never even felt it happen.

One honest thing to keep in mind: this hits some people harder than others. Some athletes lose their hunger hard after training while some barely notice. So do not assume something is wrong with you if a teammate seems to eat constantly and you do not. The point is that in a heavy block, your hunger is not a good guide to how much fuel you actually need.

Eating Enough by Bedtime Is Not the Same as Being Fueled

This next part surprises almost everyone, because it goes against the obvious math. You can add up everything you eat in a day, land on an amount that looks totally fine, and still spend most of the day running on empty.

That is not a guess. Your body runs primarily on the fuel that is available right now, in the hours you train and recover especially at higher intensities. It does not run on the total you will eventually hit by bedtime. A 2018 study in the Scandinavian Journal of Medicine and Science in Sports, led by Fahrenholtz, found that athletes who ate about the same amount each day could be fueled very differently. What set them apart was not the daily total. It was how many hours of the day they spent running low. The closest match to athletes like you comes from a 2021 study in the journal Nutrients by Lee and his team, who looked at this exact pattern in college soccer players. The ones doing better were eating more, and when the fuel showed up across the day mattered, not just the total at night.

Picture two athletes who eat the exact same food in a day. One spreads it out: something before training, real food in the hour after, a solid lunch, a full dinner. The other has a light breakfast, trains, picks at snacks all afternoon, then crushes a huge dinner at night. Add up the day and the totals are identical. But the second athlete trained on fumes and put most of the fuel in after everything that mattered was already over. Same food but completely different days. One fueled the work while the other fueled the couch.

This is the gap people miss when they say "but I eat a ton." Maybe you do. The amount can be right while the timing is off, and timing is invisible if you only look at your plate at the end of the day.

Why Week Three of a Heavy Block Feels the Worst

If the first week of a heavy summer feels fine, the second week feels a little heavy, and by the third week you are dragging through sessions you used to handle easily, this is why. And it is not what most people guess.

You did not get out of shape in three weeks. You started each day with a little less in the tank than the day before, and it stacked up.

Here is the mechanism. High-volume training drains your stored fuel more than almost anything else, and food is what refills it. According to a 2016 review in the Journal of Applied Physiology by Burke, van Loon, and Hawley, hard training burns through your stored fuel, and eating carbs over the hours afterward is what fills it back up. So when your fuel falls a little short, you do not fully top off overnight. You start the next day a step behind. One day is no big deal. But a heavy summer is day after day after day, and the small gap stacks. A few weeks in, you are training on a tank that never got back to full.

That is why it shows up around week three instead of week one. The shortfall is small on any single day and loud across a month. There is no single bad day to point at, which is exactly what makes it sneak up on you.

Hold onto this reframe: you are not run down. You are running low. They feel the same from the inside, but they are different problems. Run down is fixed with rest while running low is fixed with fuel, by refueling harder on the back half of the day so tomorrow starts closer to full. Adding sessions without adding fuel does not add progress. It quietly takes it away.

"Eat Less to Lean Out This Summer" Is Backwards

There is a piece of summer advice pointed straight at athletes your age: the idea that summer is the time to eat a little less and lean out while you train hard. I want to call it out, because it takes the accidental version of this problem and turns it into one you walk into on purpose.

It is backwards. When your training climbs and your fuel drops at the same time, the first thing that breaks is not how you look. It is the engine underneath where you get a step slower, your legs feel flat on days they should feel fine, you catch every bug going around, and little tweaks linger longer than they used to. That is the real cost of under-fueling a heavy block, and it shows up long before anything you can see in the mirror does. A high-volume summer is the single worst time to pull fuel out, because that is exactly when your body is asking for more.

So skip the scale talk this summer. Not the mirror. Not the number. The work. Fuel the training, and let the work do what the work does.

How to Fix It Without Counting Anything

None of this means eating more by force or tracking a single number. It means making fuel show up when your body is working, instead of waiting on a hunger signal that has gone quiet.

You replace the feeling with a plan. During the school year for student athletes, your schedule did this for you without you thinking about it: first period, a set lunch, dinner at home. Summer strips all of that out, so you rebuild it on purpose. The move is to put fuel into the hours your body is working, not pile it all at night. Here is what that looks like across a training day:

• Before training: eat something small even when you might have no appetite for it. A little beats nothing.
• Within the hour after: get real food in while your body refills fastest. A meal, a smoothie, a sandwich, whatever you will     actually reach for.
• Midday: eat a real lunch, not snacking all day on whatever is around. This is the anchor summer took away from you.
• Evening: build out dinner and add a bedtime snack so tomorrow starts closer to full.

Two things make this stick. Pick two of those meals and eat them at the same time every day, hungry or not, so the plan does the work your appetite cannot right now. And keep grab-and-go fuel where you will actually reach for it: your gym bag, a shelf in the fridge, the car.

That is the whole thing. You are not overhauling your diet. You are anchoring fuel to the hours your body is actually working, and letting the structure carry you on the days your appetite and motivation both go quiet.

The good news is that this responds to information fast. According to a 2024 study in Frontiers in Public Health by Tektunalı Akman and her team, a few nutrition lessons taught to 15-to-18-year-old athletes measurably improved how much they ate and how well they fueled over the months that followed. Under-fueling that runs on habit and a loose schedule is not a discipline gap. It is an information gap, and those close fast once someone shows you what is going on.You did the hard part already by showing up all summer. Now let the fuel meet you where the work is.

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Frequently Asked Questions

Why am I not hungry after training in the summer? Hard training, especially in heat, turns your appetite down for a few hours afterward. That is a normal response, not a sign anything is wrong. The catch is that your body does not later ramp hunger back up to make you eat what the session cost, so fuel can quietly go missing if you wait to feel hungry before you eat.

I eat a lot. How can I still be under-fueled? Because the daily total is only half the picture. You can eat plenty by bedtime and still spend the hours that matter most, training and the window right after, running on empty. If most of your food lands at dinner, your body was under-fueled during the actual work. The amount can be right while the timing is off.

Why do I feel worse a few weeks into summer instead of better? High-volume training drains your stored fuel the most, and your body refills it from food. If your daily fuel falls a little short, those stores do not fully refill overnight, so you start each day a step behind. That small daily gap stacks across back-to-back training days, which is why it usually shows up around the third week instead of the first.

Should I eat less in summer to lean out while training hard? No. A heavy training block is the worst time to cut fuel. When your volume goes up and your fuel goes down, performance breaks first: slower play, flat legs, more illness and nagging injuries, often before anything visible changes. The goal in a high-volume stretch is to fuel the training, not shrink the food.

How do I know if I need more help dialing this in? If you are eating what looks like plenty but still fading through summer sessions, mapping your fuel to your actual training schedule is exactly what I help the athletes I work with on. If you want to really get this locked in yourself, sign up for my free 15-minute Discovery Call. It is a low-pressure way to figure out whether the timing of your fuel may be the missing piece and how we might be able to work together.

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Training hard this summer but showing up flat? The timing of your fuel is often the piece getting missed, and it is very fixable. On a free 15-minute Discovery Call, we can discuss how mapping your fueling timeline around your real summer schedule makes the work you are putting in actually show up on the field. Book Your Discovery Call

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. Thackray AE, Stensel DJ. The impact of acute exercise on appetite control: Current insights and future perspectives. Appetite. 2023;186:106557. https://pubmed.ncbi.nlm.nih.gov/37044176/
2. Fahrenholtz IL, Sjödin A, Benardot D, et al. Within-day energy deficiency and reproductive function in female endurance athletes. Scand J Med Sci Sports. 2018;28(3):1139-1146. https://pubmed.ncbi.nlm.nih.gov/29205517/
3. Lee S, Moto K, Han S, Oh T, Taguchi M. Within-Day Energy Balance and Metabolic Suppression in Male Collegiate Soccer Players. Nutrients. 2021;13(8):2644. https://pubmed.ncbi.nlm.nih.gov/34444803/
4. Burke LM, van Loon LJC, Hawley JA. Postexercise muscle glycogen resynthesis in humans. J Appl Physiol (1985). 2016;122(5):1055-1067. https://pubmed.ncbi.nlm.nih.gov/27789774/
5. Tektunalı Akman C, Gönen Aydın C, Ersoy G. The effect of nutrition education sessions on energy availability, body composition, eating attitude and sports nutrition knowledge in young female endurance athletes. Front Public Health. 2024;12:1289448. https://pubmed.ncbi.nlm.nih.gov/38550312/

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