Macros, Hydration, and Chicago Marathon

When the forecast says 80°F or higher and humid, your plan needs three pillars: carbs to go, protein to repair, and healthy fats to sustain and that's on top of smart hydration.  Here’s the “why,” plus a simple training-day menu you can actually follow.

Note:  I am going to use the same example from my last blog (45 year old female marathon runner) to build out a training-day menu.  Also, even though you may be reading this on a cool day, take notes on the importance of replenishing your fluids and macros for top perfromance.

The Macros

Carbohydrate (primary fuel).
Carbs power your pace because they top off muscle and liver glycogen and during long efforts, adding ~30 - 60 g carb per hour helps delay fatigue and keep speed steadier.  After the run, early carb intake accelerates glycogen refill. (Jeukendrup, 2014).

Protein (repair & adapt).
Aim for about 1.2 - 1.7 g/kg/day spread across meals/snacks; think 20 - 30 g per eating occasion to support muscle repair, immune function, and lean mass during heavy weeks. Pairing protein with post-run carbs enhances recovery.

Fat (long-burn energy & health).
Keep fat in the ~20 - 35% of calories range to support hormones, absorb vitamins A/D/E/K, and help you stay satisfied as very low-fat intakes can backfire for active people.  Emphasize olive oil, nuts, seeds, avocado, and fish. (McArdle, Katch, & Katch, 2019, pp. 33–34).

Hydration on a hot, sticky morning

Show up already hydrated (pale urine) from the day before and have a small pre-run drink.  During the run, most runners do well with 0.4 - 0.8 L/hour (≈14 - 27 oz/h); in heat/humidity, you’ll trend higher.  Include ~300 - 600 mg sodium/hour via sports drink or electrolyte tabs.  Replace ~1.25 - 1.5 L fluid per kg you lost post-run to fully rehydrate. (American College of Sports Medicine [ACSM], 2007).

A Mediterranean-style training day (2,350 kcal)

Scenario: 45-year-old marathoner, 13-mile training run at 6:30 a.m., hot and humid.

Target about:

• 55 - 60% carbs,
• 15 - 20% protein,
•  and 25 - 30% fat for the day. (McArdle et al., 2019).

5:45 - 6:00 a.m. Pre-run snack (200 - 220 kcal)

• 1 slice whole-grain toast + 1 banana

  • 50 g CHO,  5 g PRO, 2 - 3 g FAT

  • Why: Light, quick carbs to top off liver glycogen without GI heaviness. 

During the 13-miler (add-on “performance fuel”)

• Fluids: 14 - 27 oz/h; Sodium: 300 - 600 mg/h; Carbs: 30 - 60 g/h (e.g., 1 gel every ~30–40 min + sips of 6–8% sports drink). (ACSM, 2007; Jeukendrup, 2014).

8:10 a.m. Immediate recovery (300 - 330 kcal)

• Smoothie: 1 cup Greek yogurt, ½ cup oats, 1 cup berries, 2 tsp honey, water/ice

  • 50 g CHO, 22 - 25 g PRO, and 5 - 6 g FAT

  • Why: Early carbs + 20 - 30 g protein jump-start glycogen and muscle repair.

12:30 p.m. Lunch bowl (600 kcal)

• 1 cup cooked quinoa, ¾ cup chickpeas, cherry tomatoes & cucumber, 1 oz feta, 1 Tbsp extra-virgin olive oil (EVOO), lemon

  • 80 g CHO, 24 g PRO, and 18 - 20 g FAT

  • Why: Whole-grain + legume carbs for glycogen, olive oil for heart-healthy fats, balanced protein. (McArdle et al., 2019).

3:30 p.m. Snack (300 - 325 kcal)

• ½ whole-grain pita + 3 Tbsp hummus + 1 apple (optional: 6 oz low-fat milk if hungry)

  • 55 g CHO, 10 - 12 g PRO, and 8 - 10 g FAT

  • Why: Keeps energy steady and supports afternoon recovery.

7:00 p.m. Dinner (620 - 650 kcal)

• 4 oz grilled salmon, ¾ cup cooked farro, 2 cups roasted veggies, 2 tsp EVOO

  • 65 - 70 g CHO, 35 - 38 g PRO, and 18 - 20 g FAT

  • Why: Omega-3-rich protein + complex carbs + colorful produce = recovery and staying power. 

Daily totals (meals only):

• 2,320 - 2,380 kcal
  • 340 g CHO (≈58%)
  • 90–110 g PRO (≈16 - 18%)
  • 60–80 g FAT (≈24 - 28%)

What to remember on race-like training days

• Carbs keep you moving. Use a light pre-run snack and 30 - 60 g/h during long runs in the heat. (Jeukendrup, 2014).

• Hydrate with intent. Drink ~0.4 - 0.8 L/h and include sodium; rehydrate based on weight lost. (ACSM, 2007).

• Protein at each meal/snack. Hit ~20 - 30 g to support repair and immune health.

• Don’t fear fat. Keep ~20 - 35% of calories from mostly unsaturated sources to support hormones and vitamin absorption. (McArdle et al., 2019).

Dial in these basics and you’ll feel it—steadier pacing, smoother recovery, and more joy in the miles ahead.

References

• American College of Sports Medicine. (2007). Position stand: Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377–390.  https://pubmed.ncbi.nlm.nih.gov/17277604/

• Jeukendrup, A. E. (2014). A step towards personalized sports nutrition: Carbohydrate intake during exercise. Sports Medicine, 44(S1), S25–S33.  https://pubmed.ncbi.nlm.nih.gov/24791914/

• McArdle, W. D., Katch, F. I., & Katch, V. L. (2019). Sports and exercise nutrition (5th ed.). Wolters Kluwer.

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