Everyday I'm hustling — nutrition & hydration for base training

While I've already done an episode on race-day prep (Episode 11) and exploring proper hydration and nutrition in the days leading up to an event, some astute readers have pointed out that I haven't yet discussed the much broader topic of everyday fueling — so let's dig in (metaphorically and literally).

Base training

Base training makes up the bulk of our exercise sessions. We may not specifically be working toward an event, but we are working to stay healthy — building our aerobic capacity (i.e. not our very-high-intensity anaerobic capacity), while working on endurance and efficiency.

Dietary guidance here is not too different from general advice. For example, the Dietary Guidelines for Americans recommend carbohydrates make up 45–65% of total daily calories. For a 2,000-calorie diet, the Mayo Clinic notes this can be 225g to 325g of carbs per day for the average individual. If you are working out for about an hour or so per day, getting up to 5–7g per kilogram of bodyweight per day is recommended. This means for a 70kg person (~155 lbs), that's 350–490g per day!⁽¹⁾

It is important to consider that some individuals prefer or feel better on a "keto" diet, or otherwise adopt a low-carb, higher-protein diet, citing research that it is superior. While this can be done safely, there are no proven performance advantages to low-carbohydrate training.⁽²⁾ In fact, while a low-carb, high-fat diet can increase fat oxidation/burning, long-term adherence to this diet seems to increase oxygen needs and may reduce performance compared to higher-carb diets (at least around times of exercise).⁽³⁾ There isn't quite as much data on fat intake for exercise, but focusing on high-quality fat in the diet, and keeping it to roughly 20–35% of your daily intake, is a good goal.

Build phase of training

Now, base training is certainly enough to keep someone healthy and active, but some of us will want to increase into higher levels of intensity or time commitment. At this level, as you replace some of the additional calories burned, it's important to be mindful of how you do so.

As you burn through more carbohydrates, you will need to replace them. And with long exercise sessions (greater than an hour or so at a time), I mean as you burn them. Some of the additional carbs should be in the form of gels, gummies, or carb-rich beverages during your long run or long ride. Nevertheless, some additional carb replacement should also happen pre- and post-exercise, and a good target is to increase the 5–7g per kg of weight to 6–10g per kg per day.⁽¹⁾ This can amount to quite a bit!

That said, it's also important to consider protein and its effect on the body during this period. As I have noted before, it's best to ensure consistent protein intake with meals all throughout the day, but many like to add extra protein shortly after a workout, while the muscles are recovering and building.⁽⁴⁾ Increasing protein intake to 1.6–1.8g per kg per day is a good goal. This means about 120g of protein for that 155-lb individual. In fact, getting up to 2g per kg per day can be considered periodically, especially when carbohydrate intake is lower, to help drive the metabolic response to endurance training.⁽⁵⁾

Hydration

We all know hydration is important. But it is so important that I think it deserves special mention on its own. Hydration in sports has been extensively studied, as both under- and over-hydration can lead to not just impairment in performance, but also risk of serious health consequences, particularly in endurance events (like marathons, triathlons, and the like).

One interesting rule of thumb is to keep an eye on your losses during exercise. Losing more than 2% of your bodyweight from sweat during exercise (that was not replaced) can have negative impacts on the body. Dehydration to this level has been shown to impair temperature regulation, increase cardiovascular strain, reduce power/strength, and reduce overall endurance performance by up to 10%!^(6,7) Because of this, it can even be helpful to pre-hydrate, as well as re-hydrate, though it's best not to drink so much that you gain water weight during the activity.⁽⁸⁾

In a study of collegiate athletes, 97% knew that dehydration could impair performance, but 50% erroneously believed that thirst could be a reliable indicator of hydration status — but it is not.⁽⁶⁾ For exercise 90 minutes or longer (or under more extreme conditions than usual), timed or planned drinking is a better strategy than drinking based on thirst alone.⁽⁷⁾ Our thirst is influenced by many factors and becomes a much less reliable metric during exercise — in essence, our sweat losses outpace our thirst.⁽⁷⁾

Conclusion

Alright, this has been an episode full of numbers and calculations, so I think it's important to step back and get a bird's-eye view. No, I don't expect you to weigh yourself at various points of a run to assess hydration status. And you don't need to track your intake of carbs, protein, and fat to the gram every day — but the themes here are important.

As you increase the intensity and duration of your exercise, your diet should reflect this as well. Increasing your daily intake as you increase your daily expenditure should focus on replacing carbs spent during exercise and getting more high-quality protein to facilitate muscle strengthening and building. And don't forget healthy fats — we need these for proper chemical and hormone synthesis.

Nutrition and hydration can, and should be, very personal. Heavy sweaters may need more fluid and electrolyte replacement than others. Depending on your own health risks and history, you may need to tailor your carbohydrate or total intake a bit.

Lastly, some of the most common issues that arise in these settings are hydration-related. As summer temperatures hit their peak, be mindful of your hydration status. Our bodies have several different markers of hydration, related to feelings (dizzy, lightheaded, thirsty), mechanics (faster heart rate, respirations), and other signs (weight loss, urine color). Take all of these into account when you are planning for your exercise and crafting your individual plan.

Stay active. Stay healthy. And stay hydrated.

Sources & further reading

1. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016 Mar 1;116(3):501–28.
2. Gejl KD, Nybo L. Performance effects of periodized carbohydrate restriction in endurance trained athletes — a systematic review and meta-analysis. J Int Soc Sports Nutr. 2021 May 17;18(1):37.
3. Burke LM, et al. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. J Physiol. 2017 May 1;595(9):2785–807.
4. van Loon LJC. Is There a Need for Protein Ingestion During Exercise? Sports Med. 2014;44(Suppl 1):105–11.
5. Witard OC, Hearris M, Morgan PT. Protein Nutrition for Endurance Athletes: A Metabolic Focus on Promoting Recovery and Training Adaptation. Sports Med. 2025 Jun 1;55(6):1361–76.
6. Judge LW, et al. Hydration to Maximize Performance and Recovery: Knowledge, Attitudes, and Behaviors Among Collegiate Track and Field Throwers. J Hum Kinet. 2021 Jul 28;79:111–22.
7. Kenefick RW. Drinking Strategies: Planned Drinking Versus Drinking to Thirst. Sports Med. 2018 Mar;48(Suppl 1):31–7.
8. Maughan RJ, Shirreffs SM. Development of individual hydration strategies for athletes. Int J Sport Nutr Exerc Metab. 2008 Oct;18(5):457–72.