What is Carbohydrate Loading?

Carbohydrate loading is a pre-race nutrition strategy designed to maximize muscle glycogen stores before an endurance event. When done correctly, it gives your muscles the largest possible fuel reserve at the start line — delaying fatigue and supporting sustained performance across the full race distance.

It is not eating a large pasta dinner the night before your race. That is a common misunderstanding that leads to GI distress on race morning and suboptimal glycogen storage. True carbohydrate loading is a structured 2–3 day protocol grounded in established sports nutrition research.

The Research Foundation

The science of carbohydrate loading is well established. Bergström et al. (1967) demonstrated that muscle glycogen can be supercompensated — elevated above normal resting levels — through a combination of dietary carbohydrate manipulation and reduced training load. Burke et al. (2011) established practical carbohydrate loading protocols for endurance athletes that remain the standard reference for race preparation nutrition.

The key finding: muscle glycogen stores are a primary limiter of endurance performance in events lasting longer than 90 minutes. Maximizing glycogen before the start directly improves late-race performance and reduces the likelihood of bonking.

Who Benefits From Carbohydrate Loading?

Carbohydrate loading produces meaningful performance benefits for events lasting longer than 90 minutes. This includes:

Full IRONMAN and IRONMAN 70.3 triathlon
Olympic-distance triathlon (for athletes finishing over 1:45–2:00)
Marathon and ultramarathon
Gran Fondo, Century rides, and multi-day cycling events

For events shorter than 90 minutes, carbohydrate loading provides minimal additional benefit beyond standard pre-race nutrition. A well-executed race morning meal is sufficient for sprint triathlon and 5K–10K racing.

The ANC Carbohydrate Loading Protocol

The ANC approach to carbohydrate loading follows the established research framework while applying the gut-first philosophy that guides all Angela Naeth Coaching fueling recommendations: prioritize foods and quantities your gut can tolerate, practice before race day, and never experiment with new strategies on race week.

3 Days Before Race

Begin increasing carbohydrate intake toward 8–10g per kg of body weight per day
Reduce training volume significantly — this is taper week, not a training week
Prioritize easily digestible, low-fiber carbohydrate sources
Reduce fat and protein intake proportionally to make room for carbohydrate calories

2 Days Before Race

Continue high carbohydrate intake at 8–10g per kg of body weight
Keep fiber intake low — this is not the week for vegetables, legumes, or whole grains
Stay well hydrated — glycogen storage requires water (approximately 3g of water per gram of glycogen stored)
Avoid alcohol — it impairs glycogen synthesis and disrupts sleep quality

Night Before Race

Eat a moderate, familiar meal — not a feast
Choose foods you have eaten before long training days without GI issues
Target 1–2g of carbohydrate per kg of body weight at this meal — enough to top off liver glycogen without overloading the gut
Finish eating at least 2–3 hours before your planned sleep time

Race Morning

3–4 hours before start: Main pre-race meal. 1–2g of carbohydrate per kg of body weight. Low fat, low fiber, low protein. Examples: white rice with banana, oatmeal with honey, white toast with jam and a sports drink.
60–90 minutes before start: Optional small carbohydrate top-up. 30–60g of fast carbohydrate — a gel, a banana, or a sports drink.
15 minutes before start: Optional final gel or 20–30g of fast carbohydrate to time the glucose response to the start of exercise.

Best Foods for Carbohydrate Loading

The ANC gut-first principle applies directly here: choose carbohydrate sources that are low in fiber, low in fat, and familiar to your gut. High-fiber and high-fat foods slow gastric emptying, increase GI bulk, and raise the risk of distress on race morning.

Recommended carbohydrate loading foods:

White rice
White bread and white pasta
Bananas and other low-fiber fruits
Sports drinks and carbohydrate beverages
Pretzels and plain crackers
Honey, jam, and maple syrup
Rice cakes and plain bagels
Boiled or baked white potatoes (without skin)

Foods to minimize or avoid during carb loading:

Vegetables (high fiber, low carbohydrate density)
Legumes and beans (high fiber, high gas production)
Whole grains and bran products
High-fat foods (cheese, nuts, oils, fried food)
Alcohol
New foods you have not eaten before a long training day

How Much Carbohydrate Do You Actually Need?

The research-supported target for carbohydrate loading is 8–10g of carbohydrate per kg of body weight per day for 2–3 days before the race (Burke et al., 2011). For a 70kg (154lb) athlete, this means 560–700g of carbohydrate per day — significantly more than most athletes eat on a normal training day.

This is why carbohydrate loading requires deliberate planning. It is not possible to reach these targets by simply eating more of your normal diet. You need to specifically prioritize high-carbohydrate, low-fiber foods and reduce fat and protein intake to make room for the additional carbohydrate calories.

The Race Day Fuel Planner calculates your personalized carbohydrate loading targets by body weight and race distance, with a day-by-day protocol and food guidance built in.

Common Carbohydrate Loading Mistakes

Starting too late: A single large pasta dinner the night before the race does not produce meaningful glycogen supercompensation. The protocol requires 2–3 days of elevated carbohydrate intake.

Eating too much fat alongside the carbohydrate: High-fat meals slow gastric emptying and compete with carbohydrate absorption. Keep fat intake low during the loading phase.

Ignoring fiber: High-fiber foods increase GI bulk and distress risk. Race week is not the time for salads, legumes, or whole grains, even if they are normally part of a healthy diet.

Not practicing before race day: The ANC gut-first principle: practice your carbohydrate loading protocol before a long training day in the weeks before your race. Your gut needs to be familiar with the foods and quantities you plan to use.

Overeating the night before: A large meal the night before the race causes GI distress on race morning. The goal is to top off glycogen stores, not to eat as much as possible in one sitting.

Neglecting hydration: Glycogen storage requires water. Dehydration during the loading phase limits how much glycogen your muscles can store. Stay well hydrated throughout the 2–3 day protocol.

Carbohydrate Loading for Athletes With Dietary Restrictions

The ANC fueling philosophy is built around the athlete’s actual dietary needs — not a generic template. Carbohydrate loading is fully achievable for athletes with dietary restrictions:

Gluten-free athletes: White rice, rice pasta, rice cakes, gluten-free bread, bananas, sports drinks, and potatoes are all excellent options
Vegan athletes: White rice, pasta, bread, bananas, dates, sports drinks, and fruit-based carbohydrate sources work well
Low-FODMAP athletes: White rice, white bread, bananas (unripe), white potatoes, and sports drinks are generally well tolerated

The Race Day Fuel Planner includes dietary swap options for GF, vegan, dairy-free, and low-FODMAP athletes throughout the carb loading protocol.

Frequently Asked Questions

Does carbohydrate loading cause weight gain?
Yes — temporarily. Each gram of glycogen stored requires approximately 3g of water. A fully loaded athlete may weigh 1–2kg more than normal. This is expected and beneficial. The additional weight is fuel and fluid, not fat.

Should I carb load for a sprint triathlon or 5K?
No. Carbohydrate loading produces meaningful benefits only for events lasting longer than 90 minutes. For shorter events, a well-executed race morning meal is sufficient.

Can I carb load if I normally follow a low-carbohydrate diet?
Athletes who train on low-carbohydrate diets have reduced glycogen storage capacity and may experience GI distress when suddenly increasing carbohydrate intake. If you train low-carbohydrate, discuss your race nutrition strategy with your coach well in advance of race day.

How do I know if my carb loading worked?
Muscles will feel slightly heavier and fuller than normal — this is the glycogen and associated water. You may also notice slightly higher body weight on race morning. Both are signs the protocol is working.

Where can I get a personalized carb loading plan?
The Race Day Fuel Planner builds a personalized 3-day carbohydrate loading protocol based on your body weight, race distance, and dietary restrictions — for $49.

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