If you've ever typed "how to carb load before a race" into Google, you've probably found a calculator that spits out a number and calls it a day. Plug in your age, weight, and race distance — boom, 800 grams of carbohydrates. Now what? When do you eat them? From what baseline? And does that number even account for the fact that you get so nervous before a race you can barely sip water? That's exactly the problem with generic carb-loading advice, and it's why so many athletes leave performance on the table despite following the "formula."
Rob Polenik, founder of the C3 Method and a certified strength and nutrition coach with a Master's in Human Nutrition, ACSM personal training certification, and over 3,000 clients coached across a 25-year career, breaks all of this down in this week's podcast. His approach to carb loading for peak performance isn't built around a calculator. It's built around you — your training history, your emotional response to competition, your digestive tolerance, and your current nutritional baseline.
In this post, you're going to learn the complete framework Rob uses with his athletes: how to calculate your calorie needs, how to time your carbohydrates throughout the day, how to taper protein and load carbs in the 24 hours before an event, and why what you do in training matters far more than what you do the morning of race day.
A running coach enrolled in the C3 Method Nutrition Coaching Certification recently sent Rob a popular online carb-loading calculator. It asked for gender, age, height, weight, and race distance — and it returned a carbohydrate target. On the surface, that sounds useful. But when Rob looked closer, the calculator was missing some enormous pieces of the puzzle.
It didn't ask about your current diet. It didn't factor in your training volume leading into the event. It didn't consider whether your glycogen stores were already full, half depleted, or running on empty. It had no concept of whether you're a nervous eater who can barely stomach a banana before a race or someone who can put away a full breakfast and feel great. And it gave a number — 800 grams of carbohydrates, in Rob's case — with zero context for how to distribute that over time.
Here's the thing: carb loading doesn't exist in a vacuum. It's a strategy layered on top of your existing nutritional habits. If you've been chronically undereating carbohydrates (which Rob says is the norm among endurance athletes he works with), your glycogen stores are likely already depleted. Loading from that state looks completely different than loading from a state of near-full glycogen.
The calculator also ignored one of the most critical factors of all — individual physiology and emotional state on competition day. Two athletes can follow the same protocol and have completely opposite outcomes. That's not a flaw to work around. It's the whole point of personalized coaching.
Not all athletic events demand the same energy systems, and that changes how you should approach carb loading entirely.
If you're running a half marathon or full marathon, you're sustaining a moderate, steady-state effort for anywhere from 90 minutes to several hours. Your body is burning through glycogen at a relatively constant rate the entire time. Your ability to refuel during the event is limited — gel packs and sports drinks help, but your stomach has to cooperate while your legs are moving. That means the carbohydrate reserves you walk to the start line with matter enormously.
Powerlifting and strongman competitions look nothing like this. A powerlifter might do three max squat attempts, then sit around for 90 minutes before warming up for bench. Three more attempts, another two-hour gap, then deadlifts. The energy demand is explosive and brief — high spikes of effort separated by long recovery windows. That means you have actual opportunities to refuel between efforts. A strongman at a local competition might cycle through five events in a single day, with real food available between each one.
This distinction matters because strength sport athletes can rely on mid-event refueling to a degree endurance athletes simply can't. Their pre-event carb loading strategy can be slightly less aggressive, while an endurance athlete needs to show up with their glycogen stores as full as possible. Knowing which category you fall into is the first step to building the right carb-loading plan.
The most important thing Rob emphasizes — and the thing that calculator completely ignored — is what you're eating right now, weeks and months before the event.
When endurance athletes come to Rob, he sees the same pattern almost every time: they're undereating protein, mistiming their carbohydrates, and eating at or below maintenance calories when their training demands more. The result? They look "skinny fat," they're battling nagging small injuries, and their performance has plateaued or is actually declining.
Here's the framework Rob uses to establish a proper baseline:
Use the BMR calculator at calculator.net. Enter your gender, age, height, weight, and body fat percentage if you know it. The tool will give you a maintenance calorie estimate based on your activity level. That's your anchor number.
For endurance athletes, Rob recommends 0.8 grams of protein per pound of body weight. If that feels like a stretch from where you are now, start at 0.6g, get comfortable over a few weeks, then bump to 0.7, then 0.8. Don't try to jump straight there if your digestion isn't used to it.
Once your total calories and protein are set, the remaining calories go to carbohydrates and fats. The split between the two is largely preferential — if you feel better on higher fat, run with it. If you perform better with higher carbs, structure it that way. What matters is that your total calories and protein are dialed in first.
Total macros matter. Timing matters just as much. Rob uses a simple mental model to structure carbohydrate timing around your activity.
Break your waking day into three blocks of roughly five to six hours each. If you're awake for 16 hours, that gives you three windows. Start by distributing your calories and protein evenly in thirds — one third per window. Get comfortable with that consistency before you try anything more complex.
Once that's dialed in, you shift your energy nutrients (carbs and fats) to peak around your training window:
The principle is always the same — eat into the activity, eat away from it when it's over. If you train in the mornings, you can actually carb load the night before by eating a significant portion of your carbohydrates at your last meal. Your body stores them as glycogen overnight, and you wake up with a full tank. This only works if your glycogen is partially depleted by end of day — otherwise those extra carbs go to fat, not your muscles.
The goal is simple: the timing of your food should mirror the timing of your effort.
This is where Rob's protocol gets specific, and it's a meaningful departure from what most athletes do.
The day before your event, you're tapering your activity down. You're probably doing very little physically — just trying to stay loose and rest. On this day:
By the end of that day, your muscles should be well-stocked with glycogen. You wake up on race morning feeling full of energy — not heavy, not bloated, but loaded.
On the morning of the event, eat what you've already been practicing in training. Don't try something new. If you can handle solid food — graham crackers, Honey Stinger waffles, cereal like Cheerios or Frosted Flakes — great. If nerves kill your appetite, drink your carbs. Gatorade, a simple sports drink, or diluted juice can get glucose into your system without overwhelming your digestive tract. Avoid high-fructose juices if your stomach is sensitive — fructose can cause cramping and GI distress during effort.
The key phrase here is what you've already been practicing. Race morning is not the time to experiment. Your training runs and sessions are where you figure out what your stomach can handle at 6 a.m. before hard effort.
Rob is clear about one thing: there is no single carb-loading protocol that works for every athlete. Here are the variables that shift the strategy dramatically:
Your emotional response to competition. Rob describes his own experience as a competitive powerlifter — he gets so fired up before events that he forgets to eat and has to remind himself to fuel. High-adrenaline athletes may naturally gravitate toward a higher-fat approach on event day because they don't need a carbohydrate-driven energy spike at the start — their adrenaline handles that. Athletes who feel flat or anxious before events often do better with higher carbs, which give them a more immediate energy lift.
Your digestive tolerance. One of Rob's half-marathon clients hit a massive PR — minutes off her time — after finally dialing in her nutrition. Another client could only manage small sips of water while running and still performed well. Both approaches can work. The goal is finding your upper limit for fuel intake before GI distress kicks in.
Your sport. A powerlifter between attempts can eat a muffin, a bagel with jelly, and some Gatorade, and their body will store that for the next effort. A marathoner at mile 15 needs something that will absorb fast and not cause a bathroom emergency.
None of these factors show up in a calculator. They only come out through guided experimentation over time.
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Q: How many days before a race should you start carb loading?
Rob's approach starts weeks before the event — not days. The foundation is your everyday nutrition baseline: are your calories appropriate, is your protein dialed in, are your carbohydrates timed around your training? The specific "load" phase — dropping protein and increasing carbs — happens the day before the event, but that only works well if your glycogen stores are being managed properly on a daily basis leading in.
Q: How many grams of carbs do you need to carb load?
This varies dramatically by individual and can't be accurately answered by a generic calculator. The better question is: what are your total daily calories, what's your protein target, and what's left for carbohydrates and fats? On the day before your event, you shift more of your total calories into carbohydrates by cutting protein intake in half and replacing those calories with carbs. The absolute number depends on your size, training history, and current dietary habits.
Q: Should you carb load before a half marathon or only a full marathon?
Carb loading is beneficial for any sustained endurance event lasting 90 minutes or more, which includes most half marathons and all full marathons. For shorter events, your existing glycogen stores may be sufficient, though your daily nutritional timing still matters for performance. The intensity and duration of your specific race, plus your current glycogen status, should guide the decision.
Q: What foods are best for carb loading the night before a race?
You want easily digestible, lower-fiber carbohydrate sources that won't bloat you or cause GI issues. Common options Rob mentions include pasta, rice, bagels with jelly, cereal, and other simple carbohydrate foods you've already tested in training. The most important rule: don't introduce any new foods the night before a race. Stick to foods your digestive system already knows.
Q: Can you carb load for strength sports like powerlifting?
Yes, though the strategy looks different than it does for endurance events. Powerlifters have long recovery windows between attempts during a competition, which means they can refuel more actively throughout the event day. The carb-loading concept still applies in the days leading into competition, but the event-day feeding strategy is more flexible — you can eat more substantial foods between squat, bench, and deadlift sessions than a marathoner can mid-race.
Q: What should you eat on the morning of a race if you have a nervous stomach?
If solid food feels impossible, drink your carbohydrates. A sports drink, diluted Gatorade, or a simple sugar-based fluid can deliver glucose without the digestive burden of solid food. If you can manage something solid, keep it simple and tested — animal crackers, graham crackers, Honey Stinger waffles, or a small bowl of plain cereal. The key is that whatever you consume on race morning should be something you've already practiced eating before hard training sessions, not something you're trying for the first time.
Carb loading for peak performance isn't a number you get from a calculator. It's a process — one that starts weeks before your event, builds through consistent daily nutrition habits, and culminates in a smart, personalized taper in the 24 to 48 hours before you compete. The athletes who get this right aren't just eating more carbs. They're eating the right carbs, at the right times, from the right baseline, in a way that their specific physiology can actually use.
The framework Rob outlines is clear: get your calories in range, set your protein at 0.8 grams per pound of bodyweight, time your energy nutrients to peak around your training, and then — the day before your event — drop protein in half and redirect those calories into carbohydrates. Practice this process in training, not on race day. Know your emotional state and what that means for your fuel preferences. And accept that some of this is trial and error — but it's informed trial and error, guided by principles that actually work. That's what separates athletes who PR from athletes who wonder why they stalled.
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Want to hear Rob walk through this entire framework in his own words, including the story behind his client's half-marathon PR and his own powerlifting competition experiences? Tune into the full episode below.