Real-world examples of glycogen loading vs. carb restriction: 3 examples that actually matter

3 real-world examples of glycogen loading vs. carb restriction

Let’s start with the good stuff: real athletes, real decisions, and real trade-offs. These are the kinds of examples of glycogen loading vs. carb restriction that actually show up in practice, not just in textbooks.

Example 1: Marathon runner using classic glycogen loading vs. low-carb “fat adaptation”

Scenario: A recreational marathoner running 40–50 miles per week is targeting a 3:30 finish. They’re trying to decide between a traditional glycogen loading strategy and a low-carb build-up with a small carb bump before race day.

Glycogen loading approach

This runner follows a fairly standard protocol used in endurance sports research:

• 6–7 days out: Training volume tapers, daily carbs sit around 4–5 g/kg.
• 3 days out: Carbs increase to roughly 8–10 g/kg body weight per day, mostly from rice, pasta, potatoes, oats, and sports drinks.
• Race-eve dinner: Carb-heavy meal, moderate protein, low fat and low fiber.
• Race morning: 1–4 g/kg carbs in the 2–4 hours before the start (bagels, toast, banana, sports drink), then small carb top-ups during the race.

This is a textbook example of glycogen loading vs. carb restriction at work: the athlete deliberately tops up muscle glycogen to delay fatigue and reduce the risk of “hitting the wall.” Research from the American College of Sports Medicine and position stands summarized by the National Institutes of Health show that high carbohydrate availability like this consistently improves performance in endurance events lasting longer than 90 minutes.¹

Result: The runner reports steady energy, fewer late-race slowdowns, and faster average pace compared with long runs where they went in on a normal or low-carb day.

Carb restriction / “fat adaptation” approach

Same runner, different training block:

• Weeks 1–3 of the training cycle: Carbs restricted to ~2–3 g/kg on many days, with several long runs started in a low-glycogen state (morning runs after a lower-carb evening meal).
• Last 7–10 days before the race: Carbs gradually increase, but never reach the classic 8–10 g/kg loading range.

This is a clear example of carb restriction in an endurance setting. The goal is to increase fat oxidation and “teach” the body to spare glycogen.

Result: The runner notices they can complete long, easy runs with fewer mid-session gels. However, race-pace workouts feel harder, and peak speed suffers. That lines up with 2020–2023 data showing that while low-carb, high-fat strategies can increase fat burning, they often reduce performance at higher intensities where glycogen is the preferred fuel.²

Takeaway: For a time-goal marathon, the glycogen loading example generally wins. Carb restriction can have a place in early base training, but going into race week with high glycogen availability is still the better bet for most runners.

Example 2: Soccer player balancing glycogen loading vs. carb restriction across a long season

Team-sport athletes live in the gray area: they need repeat sprints, quick changes of direction, and the ability to recover between matches. Here’s a real example of glycogen loading vs. carb restriction: 3 examples rolled into one season for a competitive adult soccer player.

High-intensity match week: targeted glycogen loading

During a week with two critical matches (say Wednesday and Saturday), the player and coach agree to increase carbs:

• 48 hours before each match: Carbs nudged up to ~6–7 g/kg.
• Day before match: Main meals are starch-heavy (rice bowls, pasta with light sauce, potatoes, tortillas), plus fruit and sports drinks.
• Match day: Carb-based breakfast and lunch, then 30–60 g of carbs in the 1–2 hours before kickoff.

This is a more moderate example of glycogen loading—not a full marathon-style load, but enough to ensure glycogen stores are topped up. Studies on soccer and rugby players show that higher muscle glycogen is associated with more high-intensity sprints and better work rate in the second half.³

Light training week: controlled carb restriction

In a lighter week with mostly technical drills and minimal conditioning, this same player pulls carbs down:

• Daily carbs: ~3–4 g/kg on non-match days.
• Focus: Protein for recovery, plenty of vegetables, moderate fats.

This is a practical example of carb restriction without going full ketogenic. The player is not chasing maximum fat adaptation; they’re simply matching carbs to training load to maintain body composition and avoid unnecessary weight gain.

Preseason body-composition block: sharper carb restriction

Before the season, the coach wants the player slightly leaner without sacrificing power. For 3–4 weeks, they use a more aggressive carb strategy:

• Rest days: Carbs down to ~2–3 g/kg, mainly around the training window.
• Heavy conditioning days: Carbs up to 5–6 g/kg.

Again, this is a nuanced example of glycogen loading vs. carb restriction in the same athlete. They’re not choosing one philosophy forever; they’re cycling carbs based on the calendar.

Takeaway: For intermittent, high-intensity sports, the best examples of glycogen loading vs. carb restriction show that timing and context matter more than ideology. Heavy weeks and key matches favor higher carbs and partial loading; lighter weeks can tolerate some restriction.

Example 3: Powerlifter using carb restriction for weight class vs. glycogen loading before meet day

Strength and power athletes don’t rely on glycogen in the same way as marathoners, but it still matters—especially across long training sessions and multi-attempt competitions.

Carb restriction for weight management

A 198-pound powerlifter wants to compete in the 181-pound class. Over 8–10 weeks, they:

• Reduce daily carbs to ~2–3 g/kg on non-lifting days.
• Keep carbs mostly before and after training on lifting days.
• Use higher protein (2.0–2.5 g/kg) to maintain muscle.

This is a strategic example of carb restriction used to gradually lower body weight while maintaining strength. Because training sets are relatively short, the lifter can still perform well even with lower glycogen, as long as total calories and protein are adequate.

Glycogen loading in the final week

Once they’ve made weight (or are close), the strategy flips:

• 3–4 days before meet: Training volume drops, carbs increase to ~4–6 g/kg.
• Day before meet: Carb-heavy meals with moderate sodium and fluids to refill glycogen and support a slight rebound in body weight.

This creates a subtle but meaningful example of glycogen loading. The lifter doesn’t need marathon-level carb intake, but topped-up glycogen helps with:

• Better bar speed across attempts
• Less perceived fatigue in a long meet
• Improved muscle fullness (which can also help with leverages and stability)

Takeaway: For strength athletes, the best examples of glycogen loading vs. carb restriction are about making weight without tanking performance, then using a short loading window to feel strong and explosive on meet day.

How glycogen loading and carb restriction actually work

To make sense of these examples of glycogen loading vs. carb restriction, you need a quick look at the physiology.

• Glycogen is stored carbohydrate in your muscles and liver.
• High-intensity exercise—sprinting, heavy lifting, race-pace running—leans heavily on glycogen.
• When glycogen is low, you feel flat, heavy, and slow; your perceived effort climbs.

Glycogen loading increases the amount of stored carbohydrate beyond normal levels. Classic research showed that combining a short taper in training with high-carb intake can raise muscle glycogen well above baseline. More recent work supports a simpler version: reduce training volume and increase carbs in the last 1–3 days before a big event.⁴

Carb restriction pushes your body to rely more on fat as a fuel, especially at lower intensities. That can:

• Help with weight loss
• Improve metabolic flexibility in some athletes
• Possibly support long, low-intensity efforts when carbs are limited

However, 2020–2024 research continues to show that when intensity is high, athletes with low glycogen often see reduced performance.⁵ That’s why so many real examples include both strategies at different times of the season.

Authoritative overviews from sources like the National Institutes of Health and Mayo Clinic emphasize that carbohydrate needs depend heavily on sport type, intensity, and duration, not just body weight.⁶⁷

More practical examples of glycogen loading vs. carb restriction in daily training

To round this out, here are a few more everyday examples of glycogen loading vs. carb restriction that show up in real training plans.

Endurance cyclist in a training camp

A cyclist doing a 5-day training camp with back-to-back 4–5 hour rides might:

• Use a mini glycogen load (7–8 g/kg carbs) for 1–2 days before the camp.
• Maintain high carbs during the camp, 60–90 g/hour on the bike.

This is a strong example of glycogen loading used to survive and benefit from a very high-volume block.

Recreational CrossFit athlete cutting for aesthetics

A CrossFit athlete who wants to lean out for summer might:

• Keep carbs low (2–3 g/kg) on rest days.
• Raise carbs to 4–5 g/kg on days with long metcons or multiple sessions.

That pattern is another everyday example of carb restriction, where carbs are earned by training stress rather than consumed at a flat level.

Ultra-runner using mixed strategy

Many modern ultra-runners use a hybrid approach:

• Early in the season: more low-carb long runs to increase fat utilization.
• Closer to race day: more carbs overall, plus a 2–3 day glycogen loading phase before the event.

This hybrid model is one of the best real examples of glycogen loading vs. carb restriction coexisting in the same program.

When to favor glycogen loading vs. carb restriction

Looking across all these examples of glycogen loading vs. carb restriction: 3 examples and more, some patterns are consistent.

You’re more likely to benefit from glycogen loading if:

• Your event lasts longer than 90 minutes.
• You care about peak performance, not just finishing.
• Your sport involves repeated high-intensity efforts (soccer, basketball, hockey, CrossFit competitions).

You’re more likely to benefit from carb restriction (at least part of the time) if:

• You’re trying to lose weight or make a weight class.
• Your training is mostly low-to-moderate intensity.
• You’re in an off-season or base-building phase.

The best examples from elite and sub-elite sport in 2024–2025 show that very few high performers are permanently low-carb or permanently in glycogen loading mode. Instead, they cycle carbs with training load, competition schedule, and body-composition goals.

If you want to apply this yourself, a sports dietitian or knowledgeable sports physician can help you fine-tune the numbers. The Academy of Nutrition and Dietetics and Sports, Cardiovascular, and Wellness Nutrition (SCAN) group provide directories you can use to find qualified professionals.⁸

FAQ: examples of glycogen loading vs. carb restriction

Q: What is a simple example of glycogen loading for a half marathon?
A: For many runners, a straightforward example of glycogen loading looks like this: taper your training in the final 2–3 days, then raise carbs to about 7–10 g/kg per day during that time using familiar foods like rice, pasta, potatoes, oats, fruit, and sports drinks. Eat a carb-focused dinner the night before and a carb-rich breakfast on race morning. This mirrors the examples of glycogen loading vs. carb restriction used in endurance research and is usually enough for a half marathon.

Q: Can you give an example of carb restriction that doesn’t wreck performance?
A: A practical example of carb restriction is a strength athlete or recreational lifter who keeps carbs lower (around 2–3 g/kg) on rest days and higher (4–5 g/kg) on heavy training days. They still get enough carbs to support performance when it matters, but total weekly carbs and calories are lower, which can support fat loss.

Q: Are there examples of athletes combining glycogen loading and carb restriction in the same season?
A: Yes. Many endurance athletes spend early base phases with more carb restriction on easy or long, slow days, then switch to higher carbs and occasional glycogen loading as races approach. The ultra-runner and marathoner examples above are typical of this hybrid strategy.

Q: Is carb restriction safe for high school or college athletes?
A: It depends on how aggressive the restriction is and the sport involved. Very low-carb or ketogenic diets can be problematic for young, growing athletes who need energy for both training and development. Organizations like the CDC and major sports nutrition groups emphasize adequate energy and carbohydrate intake for youth athletes, especially in high-intensity sports.⁹ Light carb cycling can be fine, but extreme restriction should be supervised.

Q: How do I know if glycogen loading worked for me?
A: The best examples of glycogen loading vs. carb restriction in practice share a few signs when loading works: you feel more energetic early in the event, your pace or power is more stable, and you avoid the dramatic late-race crash you might have experienced before. Tracking pace, heart rate, and perceived exertion across similar events is a good way to see the difference.

Bottom line: The smartest athletes in 2024 aren’t arguing about whether carbs are good or bad. They’re using real-world examples of glycogen loading vs. carb restriction to match their fuel to their sport, their schedule, and their goals. You can do the same—start with one of the scenarios above that looks most like your situation, test it for a training block or event, and adjust from there.