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Make Your Own Endurance Fuel

Contact me if you’re looking for a personalized nutrition strategy. Get the most out of training and recovery for your event.


Make your own endurance fuel at ~3x lower cost, with a wide possibility of flavors and customizations. That’s cash towards your next race or investment into training, nutrition, and gear!


Endurance fueling – practice makes perfect

Single and multi-stage endurance events result in sizeable losses to energy stores, water, and electrolytes. Your endurance fuel should offset these losses and mitigate fatigue from dehydration and lower availability of fuel to contracting muscles. Experimentation and practice of fluid and food intake in training is important to quantify your appropriate level of carbohydrate and salt intake for events.

The risk of developing gastrointestinal (GI) distress increases twofold for those not accustomed to fluid and food ingestion during exercise,[1] and >30% of athletes exhibit one or more GI symptoms during exhaustive endurance events. [2] It’s likely attributable to a combination of maldigestion and malabsorption of nutrients, changes in transit time of nutrients through the gut, and improper fluid and nutrient intake. Experimentation and continued practice can be the difference between an all-time best and a DNF/DOR. Use training time wisely to understand what works/doesn’t work for you. Consider that your gut may not behave the same at hour one versus hour eight or more.

A good liquid endurance fuel will:

  • Replace water. As little as 2% decrease in body water can impair performance [3], and insufficient fluid replacement may increase the frequency of GI symptoms.[4] Replacement rate can vary considerably based on climate, exertion, body composition, and other factors, but a good base is in the 0.45-0.75 L/h range for extended submaximal efforts.[5]
  • Replace salt. Electrolyte replacement depends primarily on sweat rate, dietary practices, acute consumption, and genetics.
  • Attenuate energy deficit (provide calories).
  • Be near isotonic. Fluid should have similar concentration of solutes as blood plasma (275-295 mOsm/kg). Drinking a fluid with similar osmotic pressure as body fluids supports body water-electrolyte balance.
  • Encourage drinking. Should be tasty enough to make you want to sip. Sipping frequently is better than periodic gulping to maximize fluid and nutrient uptake.

Endurance fuel components and taste

Summary of ingredients of popular endurance fuels and the taste they impart:

Making your own endurance fuel

Endurance Fuel

Weighing the powders: to precisely weigh out powders, you’ll need a digital scale that can measure to the tenths of grams to make individual servings. I find it’s more practical to prepare in larger batches (in which case you can use a food scale to the hundredths). After mixing, place in a large mason jar, shake well and store for later use.

  • Electrolytes: Sweating rate and electrolyte concentration in sweat is variable based on physiology, intensity of exercise, and environment. The below table summarizes the main components of sweat on a per liter basis. For the recipe, I selected moderate levels. This endurance fuel, similar to popular products on the market includes major and minor electrolytes, with sodium and chloride the most important. If you’re getting sufficient potassium, calcium, and magnesium from your diet, adding them to your electrolyte is unlikely to provide benefit.
  • Carbohydrate (CHO): Glucose, or combinations of glucose + fructose, and sucrose rapidly replace muscle glycogen and maintain blood glucose required for muscle contraction, and support water absorption.[1,7] A good base for long submaximal efforts is 30-50g/hr,[5] supplementing with carbohydrates from food or gels as appropriate. For high intensity efforts, pushing upwards of 100g/hr is possible (with gut training and use of multiple transportable carbohydrates). [6] The recipe uses 70g/L of glucose (resulting in an intake rate of 35g-50g CHO/hr with my estimate total fluid intake rate).
  • Caffeine: Caffeine is an established ergogenic aid for sustained endurance exercise, primarily by reducing perception of pain [8,9], enhancing cognitive performance, [10] and increasing time to fatigue in skeletal muscle contraction.[11] Addition of caffeine is entirely optional; a moderate “topping off” dosage for multi-hour events is in the 70-125mg/hr range, with a pre-dosage of 3-6mg/kg BW 30-90 min before event start. Many prefer to supplement with caffeine separately using gels or other means.
  • Flavorings: This recipe is fairly tart using 2g of citric acid per liter; adjust this amount up or down to your preference. To change the flavor, Nature’s Flavors powders come in a brilliant variety. For the recipe, I used 2g apple powder which in combination with the citric acid provides a sour apple flavor, much like a Jolly Rancher candy.

Composition and cost comparison

After extensive personal testing on multi-hour training runs in both hot/arid and hot/humid climates and a elevation trail 50K on a hot day, here’s the final comparison. I was still happy drinking it until I finished just under 7 hours later.

If you’re training extensively, you’ll easily save several hundred dollars per year on fuel by making your own. Have fun and reach out anytime if you have questions!

[1] de Oliveira, E.P.; Burini, R.C.; Jeukendrup, A., Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations, Sports Med. 44, S79-85, (2014).

[2] Romijn, J. A.; Coyle, E. F.; et al., Regulation of endogenous fat and carbohydrate metabolism in relation to exercise intensity. American Journal of Physiology: Endocrinology and Metabolism, 265, E380–E391, (1993).

[3] Jeukendrup, A.; Gleeson, M., Henry. Sports Nutrition, Human Kinetics; 2nd edition (2009).

[4] Smith, J.W.; Bello, M.L.; Ffion, G., A Case-Series Observation of Sweat Rate Variability in Endurance-Trained Athletes, Nutrients, 13, 1807, (2021).

[5] Tiller, N.B.; Roberts, J.D.; et al., International Society of Sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing, J Int Soc Sports Nutr., 16(1), 50, (2019).

[6] Trommelen, J.; Fuchs, C.J.; et al., Fructose and Sucrose Intake Increase Exogenous  Carbohydrate Oxidation during Exercise, Nutrients, 9(2), 167, (2017).

[7] Giso, C.V.; Summers, R.W.; Schedl, H.P.; Bleiler, T.L., Intestinal water absorption from select carbohydrate solutions in humans. J. Appl. Physiol. 73, 2142, (1992).

[8] Laurent. D.; Schneider, K.E.; Prusaczyk, W.K.; et al., Effects of caffeine on muscle glycogen utilization and the neuroendocrine axis during exercise. J Clin Endocrinol Metab, 85, 2170, (2000).

[9] Grossman, A; Sutton, J.R., Endorphins: What are they? How are they measured? What is their role in exercise?, Med Sci Sports Exerc, 17 ,74, (1985).

[10] Ivy, J.L.; Costill, D.L.; et al., Influence of caffeine and carbohydrate feedings on endurance performance. Med Sci Sports Exerc, 11, 6, (1979).

[11] Kalmar, J.M.; Cafarelli, E. Effects of caffeine on neuromuscular function. J Appl Physiol, 87, 801, (1999).

[12] Vitale, K; Getzin, A., Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients, 11(6), 1289, (2019).

Disclosure: I’m a a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. This help support keeping my website ad-free.

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Unwrapping Nutrition Labels

Nutrition Labels

What we see and believe from reading food labels affects what we buy. Unwrapping nutrition labels can be difficult. Here are a few things you probably don’t know about the Nutrition Facts label.

Food manufacturing companies grow revenue and profit when they can effectively address evolving customer desires and deliver additional real (or perceived) value. Increasing demand for convenience food is driving significant innovation across the industry in an effort to drive growth and meet customer expectations. Products frequently target specific customer segments looking for certain food characteristics, e.g. “low-carb”, “natural”, “keto-friendly”, and “plant-based”. You’ve likely seen the increasing number of protein and nutrition bar options, cereals, crackers/chips, spreads, and other on-the-go foods being marketed to you for health, weight management, performance, or some other factor.

To help consumers to compare nutritional value between products, nutrition labels based on a standardized set of nutrition facts was implemented in 1994. They are regulated by the US Food and Drug Administration (FDA).

Updated Nutrition Facts

Regulations around nutrition labels on foods, and legally-allowable marketing claims have arguably been behind the times for well over a decade and have not kept pace with new product innovation. In a positive step forward, this year the Nutrition Facts Label received a significant overhaul. The updated label requirements have been designed to allow consumers to make better-informed choices in the interest of public health – accounting for the linkage between diet and chronic diseases such as obesity and heart disease. You may have noticed some of the obvious changes, such as the product calories being printed in a larger and in bold font. It’s important to understand what information the labels and packaging can provide. Here are a few deeper insights about nutrition labeling of which you may not be aware.

1: Some marketing phrases legally mean something, while others don’t.

Certain marketing phrases have a defined legal meaning per the FDA and can only be used on products if they meet certain criteria.

  • “Low Calorie” – no more than 40 calories for > 30g serving
  • “Light/Lite” – this one can have three different meanings. 1) For foods containing more than 50% calories from fat, the light version must be reduced in fat by 50%. 2) For foods containing less than 50% calories from fat, total calories in light version should be at least 1/3 less. 3) Could mean that the light product has 50% less sodium than regular version.
  • “Low-fat” – 3g or less of total fat per serving
  • “Fat-free” – < 0.5g of total fat per serving
  • “A good source of XX” – contains 10-19% of the Daily-Recommended-Value (DRV) in the amount that is typically consumed.
  • “High in XX” – contains 20% or more of the Daily-Recommended-Value (DRV) in the amount that is typically consumed.

As you can see, a “light” version of a food does not necessarily mean it is low calorie, but it’s probably lower in calories. The FDA is serious about labels that can be misleading. For example, if a food is labeled as no sugar or zero sugar, it must also place the statement on the label “not a low-calorie food” unless it also meets that criteria. Many consumers equate sugar-free foods with being low calorie – which is often not the case.

Many other claims utilized on packaging have no standard definition, and food manufacturers need to make sure they are not running afoul of the FDA so are careful in the way they state product features.

A prime example – you won’t see packaging that explicitly states a food is “low carb”. The FDA has no standard definition on what “low” means in terms of carbohydrates. Instead, the product will highlight “Net Carbs” (total carbohydrates less dietary fiber and sugar alcohols). This is a direct math calculation from from the Nutrition Label Facts and so removes subjectivity.  

Another work around is to portray a food as fitting within a type of diet plan without qualifying it, e.g. “keto-friendly” or “paleo-friendly”. These statements make no direct claims about nutritional value and benefits thus are allowable.

2: Serving sizes are larger for many foods in the recent label update.

Manufacturers must now reflect serving sizes based on the amount of food people typically consume, rather than how much they should consume. You will notice that serving sizes have grown larger. For example, a standard serving of ice cream is now 2/3 cup versus 1/2 cup.

It’s what the FDA believes is the average serving across everyone, including a 100 lb. 5’ 20-year-old female and a 250 lb. 6’ 55-year-old male. Considering this, the label serving size is not a recommendation of your portion. It’s important that you assess the right portion for you.

3: You may be getting more calories or nutrients than the package states, and there is allowable rounding.

Food companies have a lot of leeway in terms of the accuracy of their nutritional information. Calories and nutrients (including vitamins and minerals) are allowed a 20% variance. The accuracy of the information on the Nutrition Facts Label is the responsibility of the company selling the food, not the government. The FDA does go around sampling, purchasing, and analyzing products from store shelves to perform checks, but the extent and frequency of these checks is unknown.

Bottom line – it’s within legal bounds for a 200 Calorie packaged food to have 240 Calories (i.e. 200 + 20%). That being said, food manufacturers know it’s in their best interest to be a accurate as possible to keep customers happy.

The caloric value of a product containing less than 5 Calories may be expressed as zero or the nearest lower 5 Calorie increment. For example, a serving with 4 Calories can be reported as zero Calories. It’s truly rare that a food would have zero calories. Likewise, 47 calories would be rounded to 45 calories. You shouldn’t be concerned about these trace number of calories, but note they can add up if you consume a large quantity of “zero-calorie” and “low-calorie” foods.

4: The new “Added Sugars” line can be a very powerful decision-making criteria for food selection.

The new “Added Sugars” line can be immensely helpful in identifying foods that are intentionally made extra sweet to for no other reason than to be super tasty. Limit foods that have high quantities of added sugars relative to total sugar and total carbohydrates, unless you are specifically in need of a high sugar food for explicit purpose (e.g. fuel for endurance training, recovery from resistance training).

5: “Sugary” sweeteners don’t count towards “Total Sugar” or “Added Sugar” and they don’t have as many calories as typical carbohydrates.

Confused? The FDA’s assessment is based on recognition that certain sugar and sugar-like sweeteners are not metabolized by the human body in the same way as table sugar. However, they do count towards the “Total Carbohydrate” and you will often see them on a separate line item as “Sugar Alcohol”. While regular sugar is assigned 4 Calories/gram, certain other sugars and sugar alcohols are indigestible or only partially digestible and so their caloric value is assessed lower.  Everyone will derive a slightly different caloric value from many of these sweeteners depending on your own ability to digest them. Here, I provide a table of common sugary substitutes as well as the FDA’s caloric assignment.

SweetenerDescriptionFDA Caloric Assessment
AlluloseSimple sugar (epimer of fructose).
Our bodies can’t effectively metabolize allulose – it’s absorbed and passed in urine. No meaningful impact on blood glucose or insulin.
0 Cal/gr.
ErythritolSugar Alcohol. Our bodies can’t metabolize it – it’s absorbed and passed in urine. No meaningful impact on blood glucose or insulin. For some, it causes gastric distress due to fermentation in the colon.0 Cal/gr.
Mannitol Maltitol
Xylitol
Sorbitol
Sugar Alcohols. Our bodies can only partially metabolize them and they have a smaller impact on blood glucose and insulin versus sugar. These can also cause gastric distress due to fermentation in the colon.1.6-2.6 Cal/gr.

Hydrogenated starch hydrolysatesA mixture of sugar alcohols. Our bodies can only partially metabolize them and they have a smaller impact on blood glucose and insulin versus sugar. These can also cause gastric distress due to fermentation in the colon.3 Cal/gr.

You many also see sugar alcohols marketed as a reduction in total carbohydrates for lower “net carbs” or “impact carbs”. Personally, I would not categorically call sugar alcohol-containing products “free foods.” Some of these products can still contribute a significant amount of carbohydrates.

6: Some dietary fiber has calories. Also, fiber does not have to be “natural” to be beneficial.

Soluble fiber is partially digested in our gut and is assigned 2 calories/gram. On the other hand, Insoluble fibers travel to the intestine with little change and are not digested in any meaningful way to are assigned 0 calories per gram. Both are important to our diet.

Dietary fiber that can be declared on the nutrition label includes naturally occurring fibers from plants as well as certain isolated or synthetic non-digestible soluble and insoluble carbohydrates that have been approved by the FDA. Both natural and synthetic fibers are beneficial for meeting fiber intake. You may have come across ingredients such as glucomannan, beta-glucan soluble fiber, psyllium husk, cellulose, guar gum, alginate, inulin, soluble corn fiber/resistant maltodextrin, and locust bean gum. These all count toward dietary fiber and are typically added to products to promote feelings of fullness.

Did any of this surprise you? Let me know and please forward this to friends who may find it interesting.

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