Carbohydrates: The Energy Currency
Leading up to the Mexico City Marathon on August 31, thousands of runners are fine-tuning their preparations for the 42.195 km course. Beyond training and high-tech running shoes, nutrition over the five days leading up to the race is crucial for reaching the finish line. Sports nutritionists, universities, and experienced runners agree: eating well is an investment in the most important economy – your own body.
The international consensus, including the American College of Sports Medicine, Academy of Nutrition and Dietetics, and Dietitians of Canada, recommends increasing carbohydrate intake in the final week to replenish muscle glycogen stores. The guideline is clear: consume 5-7 grams of carbohydrates per kilogram of body weight five days before the race, rising to 10-12 grams per kilogram in the last 36 hours. This strategy is known as “carbo-loading.”
What to Eat for a Marathon
In Mexico, this translates to easily accessible and familiar foods like white rice, simple pasta, bolillo with jam, Maria cookies, bananas, cornstarch porridge or horchata. “Marathon day isn’t for culinary experimentation; what you eat should be what you’ve already tested during long training runs,” explains sports nutritionist Yenny Zetina in an interview with Bistronomie de El Economista.
Lower Fiber, Maintain Protein
Starting Thursday, the recommendation is to reduce fiber and fats to avoid gastrointestinal discomfort: fewer nopales, beans, or broccoli, and no fried foods. Protein levels should remain at 1.2-1.6 g/kg/day, spread throughout the day but not overshadowing carbohydrates. “It’s a mistake to think that eating more protein improves performance; in a marathon, glycogen rules,” Zetina states.
What to Eat for the Marathon
Hydration with Science and Sodium
The capital’s climate and 2,240 meters above sea level altitude increase water loss through respiration and urination. Therefore, experts recommend hydrating with beverages containing sodium (460–1,150 mg/L) to improve fluid retention and prevent hyponatremia. The American College of Sports Medicine suggests drinking 5-7 mL/kg four hours before the start, adjusting based on urine color.
During the race, the rule isn’t “drink by the clock,” but rather to drink according to thirst, avoiding losses greater than 2% of body weight while also not overhydrating with water alone. The Mexico City Marathon will have official hydration points along the route, alternating between water and isotonic drinks.
XL Maratón de la Ciudad de México. Photo EE: Eric Lugo
The Morning of the Big Day
On race day, 3-4 hours before starting, runners should consume 1-4 grams of carbohydrates per kilogram of body weight: a meal like bolillo with honey, banana, light rice and milk, or simple hotcakes. Those who have trained can add caffeine (3-6 mg/kg) an hour before, or even beet juice rich in nitrates, which some studies link to better performance at altitude.
Throughout the 42 Kilometers
The standard recommendation is to consume between 60 and 90 grams of carbohydrates per hour, preferably a combination of glucose and fructose found in gels, gummies, or sports drinks. For amateur runners taking more than 3:30 hours, 60-75 g/h is sufficient; elite runners finishing in less than two hours can tolerate up to 90 g/h or more, with months of gastrointestinal training.
After Crossing the Finish Line: Replenish and Repair
The first two hours after crossing the finish line are crucial: it’s advised to consume 1.0-1.2 grams of carbohydrates per kilogram of body weight per hour along with 0.25-0.3 grams/kg of protein to start replenishing glycogen stores and muscle repair. Foods like banana smoothie with milk, rice with chicken, or turkey sandwich fit the formula.
Experts’ Advice
Certified fitness trainers warn that pre-competition nutrition should be “easy to digest and free of irritants.” Mexican marathon runner Araíz Arriola often summarizes it this way: “You run a marathon with the legs you trained and the stomach you educated.”
In a country where gastronomy is identity, the Mexico City Marathon is also run with tortillas, breads, and rice in the invisible backpack of energy. “The economy of every step depends on what you eat starting five days before,” Zetina concludes.
