Carb loading is a strategic nutrition approach designed to maximize the body’s glycogen stores before high-intensity endurance events.
This practice is especially relevant for athletes preparing for competitions lasting longer than 60 to 90 minutes, such as marathons, triathlons, or long-distance cycling.
By increasing carbohydrate intake and reducing exercise in the days leading up to an event, athletes can delay the onset of fatigue and sustain energy for longer periods.
Carbohydrates are stored in muscles and the liver as glycogen, the body’s primary fuel during extended physical exertion. However, these stores are finite and can become depleted quickly during high-intensity efforts.
Carb loading works by elevating these glycogen reserves beyond typical levels, improving endurance and reducing the likelihood of early fatigue.
One effective method involves consuming approximately 10 to 12 grams of carbohydrates per kilogram of body weight per day for two to three days before the event, while simultaneously tapering physical activity.
For a 70 kg (154 lb) athlete, that equates to 700 to 840 grams of carbs daily, which can significantly increase muscle glycogen content.
However, the practice is not suitable for everyone or every type of exercise.
Carb loading is most beneficial for endurance events where glycogen depletion is a concern. For strength-based workouts or exercise sessions lasting under an hour, the benefits are minimal.
Engaging in carb loading for short or low-intensity workouts may lead to excess calorie intake and unwanted weight gain without improving performance.
Another common mistake is miscalculating carbohydrate needs.
Athletes may consume either too little—undermining performance—or too much, resulting in bloating or fatigue.
Tracking your current intake using a nutrition app can help you compare your baseline to loading recommendations.
Adjust your diet mindfully to avoid unnecessary spikes in calories or discomfort during your event.
A third issue involves neglecting to modify fat intake.
While fats are essential for health, consuming them in high amounts during the carb loading phase may displace valuable carbohydrates or contribute to sluggishness.
The timing and composition of meals should therefore be considered carefully to support energy needs without compromising digestive comfort.
Fiber, too, becomes a critical consideration during the loading phase.
Although fiber-rich foods are excellent for general health, they may cause gastrointestinal discomfort when consumed in large quantities before intense activity.
Switching to lower-fiber carb sources like white rice, plain bagels, or refined pasta may help reduce bloating and improve digestion in the final 48 hours before your event.
Another mistake many make is maintaining a regular or even intensified exercise schedule while carb loading.
To fully benefit from increased carbohydrate intake, it’s important to taper exercise and allow your body to store glycogen efficiently.
Exercising too hard during the loading phase may simply burn through the carbs you’re trying to store.
Working with a personal trainer or coach can help you optimize your tapering strategy.
During the carb loading phase, focus on easy-to-digest, carb-rich foods that are low in fat and fiber.
Good options include white bread, pasta, potatoes, low-fat yogurt, bananas, and fruit juices.
Limit fatty meats, creamy sauces, high-fiber vegetables, and whole grains during this time.
The goal is to maximize carbohydrate intake without digestive strain or excess calorie consumption.
Carb loading is a powerful tool when used appropriately, but it must be matched to the duration and intensity of your activity.
When done correctly, it can increase glycogen stores by up to 50 percent and significantly enhance endurance performance.
For recreational athletes or those unsure of how to approach carb loading, consulting a registered dietitian or sports nutritionist is the best way to tailor a plan to your individual needs.
Carb loading is not about eating as much pasta as possible.
It’s a calculated, science-backed strategy designed to support optimal energy levels, reduce fatigue, and improve endurance when it matters most.
With the right approach, you’ll be able to train hard, compete strong, and recover well.