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  • Amy Sotis

Are Carbohydrates Bad For You? Take a Look At Sports Nutrition Based on Science.

The following is a meal plan/fueling strategy I put together for an elite male marathoner. I am guessing you are not an elite male marathoner, however, read on for valuable information on one way to properly fuel for any athletic endurance events. This is an extremely detailed, specific diet regimen and rationale for anyone who wants to know the "why" behind sports nutrition recommendations to carb-load. This is not the only "good" way to fuel for an event - others have successfully competed with lower-carbohydrate diet plans, but for this example, science has shown that to maximize glycogen storage in muscle, sufficient carbohydrate intake is the fastest way to accomplish this and to replenish depleted glycogen levels.

Additionally, this blog post will cover the macro and micronutrients, as well as fluid intake for training and race day. The calorie recommendations are higher than the average person's needs, so if you want to adopt this plan, choose smaller portions and adjust accordingly.


Half-Marathon Runners, source: JJS Photography, Luminaries Retreat

For most people, even regular moderately active people, I would not recommend a high-carbohydrate diet. But, for someone who runs 15-20 miles a day in training, and who will likely complete a marathon in just over 2 hours, or anyone who will exercise for greater than 2 hours in one event, it is imperative! This plan will show you an idea of how a moderately high carbohydrate diet is acceptable and healthy for people who exercise regularly and need to have their muscle and liver glycogen stores replenished day after day. For someone looking to lose weight, I would modify this type of diet plan by reducing some of the simple carbohydrates and increasing protein and fat ratios. However, take note of the meal plan and the comments in the chart about what specific nutrients are in each food. Just because you eat a higher-carbohydrate diet, should not mean that its rich in chips, cookies, soda, and white bread! The following is actually a healthy high-carbohydrate diet, not one part of the SAD (Standard American Diet), laden with processed foods, refined sugar, and no-nutrient flour. Carbohydrates are not bad in and of themselves, but the type or source of your carbohydrate can make all the difference in the world to your performance, health, and weight.

The macronutrients in all foods are made up of either a Carbohydrate (4 calories per gram), a Protein (just under 4 calories per gram), or a Fat (Lipid) (9 calories per gram).

Chickpea, Grape, Red Onion Salad: Part of a healthy carbohydrate diet. Source:


The following diet analysis was prepared by Amy Sotis and may not be replicated, copied, or shared without express declaration that this is the property of Luminaries Retreat, LLC. Please feel free to share this blog post but do not copy and paste the contents of the plan without our permission first. Thank you!


The average size for an elite male marathon runner in 2011 was 5’6” tall and125 pounds (56.5 kg)1 and that will be the height/weight combination I will base particular calculations off of for my athlete example.

One research study of elite distance male runners showed the average energy expenditure in a normal training day was 3079 kcal and the carbohydrate (CHO) expenditure reached an average value of 10.0g k.g. b.w. per day.2 This is slightly lower but still in line with the basic sports medicine recommendations I will follow for my athlete for both training and race day which will plan for 3850 calories based on height, weight, and exercise output. The macronutrient breakdown for the training menu and the race-day menu will be 70% Carbohydrates, 15% protein, and 15% fat. This equals approximately 2700 calories from carbohydrates (678g), 577 calories from fat (64g), and 577 calories (144g) from protein.

Meb Keflezighi, American Marathon Champion, source:

Macronutrients & Calories:

A high-carbohydrate diet, classified as approximately 70% of all calories ingested, enhances endurance capacity compared to a normal carbohydrate diet (50%) or a low-carbohydrate diet (10%). A baseline recommendation for an elite runner would be 10-12g. kg. b.w. per day (678 g or 2,700 calories from CHO per day) and 70% of total kcal coming from CHO in order to reduce symptoms of overreaching, prevent fatigue, and restore muscle and liver glycogen.3 70% of a 3850 calorie day would be 2,700 calories coming from carbohydrate or about 700 g (4 kcal per g). For a 125 pound man (56.5 kg), this would be within the 590 - 708 g range of CHO per day and on a 3850 calorie diet, that would be about 70% of calories from CHO (on the higher end of the range). In the training period, the athlete should regularly eat food items like potatoes, pancakes, vegetables, oatmeal, and rice, which are high in glucose particularly, avoiding a large portion of carbohydrates from fructose or sucrose or galactose (dairy). A combination of simple and complex carbohydrates is recommended normally, but on race day, consume foods/drinks high in glucose and low in fiber (to not upset the digestive track). Vegetables and fruits (during training particularly) are the best sources of carbohydrates for any athlete as they have a prevalence of almost all essential vitamins, minerals, fiber, antioxidants, phytonutrients and even a little protein.


Approximately 15% of total calories should come from protein. Consequently, the recommendation for my athlete will be 144g of protein or 577 calories from protein (15% of total calories, 144g x 4 kcal=577). Researchers have shown that ingesting protein with CHO immediately after endurance exercise can promote glycogen storage. This storage could contribute to a faster recovery and better adaptation, especially in athletes who participate in several training sessions each day and throughout the week and subsequently have short recovery periods. Ingesting 0.4g. kg. b.w. of protein immediately after training and 2 hours later is a common schedule that has been shown to be beneficial.2 This amounts to 22 g of protein each mini-meal. Good sources of protein are from lean meats, eggs, dairy products (which also contain valuable vitamins and minerals for the athlete), and beans.

Healthy High Protein Foods

source: Bigstock Images


Fat will account for 15% of the diet which still constitutes a low-fat diet. Good sources of fat fall in line with general recommendations for all athletes - monounsaturated fats such as avocado, nuts, and olive oil plus the naturally-occurring fat in meat. Coconut oil is an excellent source of fat and should have a part in the athlete’s meal plan with the hope of ergogenic benefit. At 9 calories per gram, fat is more calorie-dense than either carbohydrates grams (4 calories) or protein grams (just under 4 calories). However, dietary fat is extremely important to all people, including athletes, as it provides essential fatty acids, and promotes uptake of fat-soluble vitamins into the body.3 In the muscle, fatty acids are stored as IMTG (intramuscular triacylglycerol), which can provide an important fuel during exercise.3 Fat will be 15% of total calories, 64g x 9 kcal=577 calories from fat on the daily recommendation of 3850 calories.


Avoiding dehydration is of utmost importance to a marathoner both in long, training runs and during the race itself. Because these athletes run outside, weather, as well as availability of fluids is an obstacle. Every athlete has a different sweat rate, but at a minimum, the athlete will need to be very careful to get just the right about of water to stay hydrated but not over-fill their stomach and thus become uncomfortable. If the athlete is going out for a 15 mile training run, they will need to properly place water bottles along the route, or “wear” their water and carrying small gels or food items to provide the carbohydrates and electrolytes necessary.

Sweat rates for marathon running at a 59-68 F ambient temperature is between 800-1200 ml/h and requires 500 ml/h of fluid, particularly water or a sports beverage.3 For a 2 hour race, this would be 1000 ml (1L or 33 oz). However, I would recommend doubling this amount because of the high velocity with which these runners run with absolutely no break in pace. The ideal drink for fluid replacement is one that tastes good, doesn’t cause gastrointestinal discomfort, promotes rapid gastric emptying and fluid absorption, provides energy in the form of glucose, contains glycerol to promote hyperhydration, and electrolytes and sodium (700 mg/L).3 If the weather is particularly warm or humid and sweat loss is greater, naturally the fluid requirements would go up exponentially.

Dehydration is a huge threat to athletic output and it is not wise to use thirst as an indicator of when to consume fluids - stick with the prescribed amount or go slightly above based on weather or sweat rates. By the time thirst occurs, a significant degree of dehydration (enough to impair performance) is possible


Specific Vitamins and Minerals (Micronutrients) for Athletes:

Vitamins C, D & A are especially important in muscle recovery and bone formation (along with the minerals, calcium and iron).3 In addition, zinc promotes protein synthesis, immune function, and tissue repair. Because of the strain in peak training on muscles, a recommended amount for zinc is 15-25 mg/day.5 A balanced, nutritious diet will supply adequate levels of these nutrients provided the athlete does not skip any food groups/meals regularly in the training regimen - this is particularly important when trying to achieve low body mass by restricting calories or food groups in conjunction with heavy training loads, which also might lead to immune system depression. “Excessive amounts of specific nutrients (e.g., omega-3 polyunsaturated FAs, iron, and zinc) can have detrimental effects on immune function.”3 What this means is, focus on getting vitamins from food itself, not relying on supplements.

Even though it is “tempting” to supplement with certain individual micronutrients, this is not advised, although paying attention to a diet rich in iron is a must. Without the RDA (recommended daily allowance) of 8 mg/day for iron, the athlete may be at risk for anemia or performance decrease.3 Additionally, the athlete should eat foods rich in vitamin C to facilitate nonheme iron absorption while eating iron-rich foods. Iron losses may be around 70% higher in athletes compared with sedentary people, but males can achieve an iron intake equivalent to twice the RDA through consumption of a well-balanced diet.

Being an elite athlete increases the need for some, but not all vitamins and minerals, but the athlete’s needs can still usually be met by consuming a nutritious, balanced, high-carbohydrate, moderate-protein, low-fat diet. The following chart shows which vitamins in particular are a focus in the recommended meal plans I came up with for the elite marathoner. Information cited here is compiled from various charts and information in Asker Jeukendrup and Michael Gleeson's book, "Sport Nutrition: An Introduction to Energy Production and Performance".

Top Vitamins and Minerals for Athletes

Because elite marathoners usually put in upwards of 120 miles of running per week (approximately 20 miles per day, 6 days per week) their training meal plan and their race day meal plan will not differ much, with a few exceptions. Race-day carbohydrates will be simple (not complex) to avoid fiber and thus digestion issues that can arise on race-day when exerting oneself at a higher-than-normal V02 max. The other main difference between the two menus is the addition of a carbohydrate/electrolyte drink regularly throughout the marathon itself, which will account for a significant portion of carbohydrate grams, versus the training diet which will get the majority of carbohydrate grams from grains, vegetables, fruits, and other food sources.

Sample Training-day Menu/Meal plan

Twin Cities Marathon Finisher, source: JJS Photography

Sample Race-Day Menu/Meal Plan:

Exercise-induced hyperventilation can cause cramping, emptying of the bowels, and even vomiting during the race as the pace is generally slightly faster than in training and the duration is longer.

Consequently, timing intake on race-day is imperative. Our athlete should have his last fairly large meal 3 to 5 hours before the race starts and contain approximately 300 g of CHO.3 If it is an early marathon start (sometimes as early as 7 am) the timing of the last meal will be difficult so if breakfast is eaten less than 3 hours before start time, consider increasing dinner quantity the night before and reducing breakfast to whatever feels comfortable.

During the race, approximately 70 grams of carbohydrate for each hour of the race is recommended. So, if the athlete runs just over a 2 hour marathon (which is the average elite time for males), he will need to plan for approximately 140 grams of carbohydrate during the race, with all that coming from liquids or gels, which will be quickly metabolized and not upset the stomach as much as solid food. The goal is to eat enough carbohydrate to achieve maximal exogenous oxidation rates without causing gastrointestinal problems.3

This menu was prepared with a 9 am race start time in mind.

High-Carbohydrate Diet Information

Although higher-protein diets are acceptable for many types of athletes competing recreationally and even at the elite level, for the endurance runner, carbohydrates are the most important substrate that can be taken in to promote glycogen storage in the liver and in the muscles. “Glycogen deficiency leads to reduced training intensity and response, low achievements in competitions, overtraining syndromes, low concentrations of lactate in the blood, high concentrations of ammonia in the blood, and higher protein expenditure for energy supply. To avoid these problems, large carbohydrate intake for endurance athletes generally is accepted.”2 There are so many wonderful food sources of carbohydrates beyond the simple pasta/rice/bread/cereal/potato/sweets concept that some people think of when they think “high-carbohydrate” diet. Vegetables, fruits, and beans are primarily carbohydrate and the opportunities are endless to incorporate a mixture of colorful foods into the high-carbohydrate diet recommended. In fact, if the athlete relies only upon the previously-mentioned “starches” they will miss out on all the valuable vitamins, minerals, and phytonutrients in the colorful carbohydrate sources. Some studies indicate that highly-trained muscles can store 20-50% more glycogen than untrained muscles.4 More stored glycogen means more fuel for working muscles to use, and consequently that will be useful to propel the elite marathoner toward their goal time without losing their endurance or pace.


Carbohydrate loading is the concept of increasing glycogen stores, and will increase endurance by about 20% during an endurance event.3 Carbohydrate intake in training will replenish muscle glycogen stores, but carbohydrate intake in the hours before competition will optimize liver glycogen stores only. So, carbohydrate loading is necessary both periods to avoid a “bonk”. The initial muscle glycogen stores will be depleted after about 45 minutes of running, and then the liver stores will be called upon to utilize glucose, and ingested carbohydrate during the event will be utilized as well to continually supply the needed glucose.3

source: Chequamegon Fat Tire Festival, Wisconsin

Super compensation Protocol & Glycemic Index

In training, one approach many athletes have found successful to increase muscle glycogen stores, is called “supercompensation protocol”. A moderate supercompensation protocol is recommended versus the classical protocol, which is a taper in training as the race approaches and going from low to high carbohydrate intake over 6 to 7 days. This has been shown to stimulate glycogen resynthesis and will result in high muscle glycogen concentrations.3 A disadvantage of the classical supercompensation protocol (high-protein, high-fat diet seven to four days before the event, with high-carbohydrate intake in the three days before the event) is hypoglycemia and gastrointestinal problems in the low-carbohydrate period, Choosing high glycemic index drinks/foods on race day will quickly deliver glucose to the athletes’ bloodstream. Glycemic Index (GI) is the increase in blood glucose and insulin in response to a standard amount of particular carbohydrate-rich foods. There are many charts available to anyone to highlight which foods are high on the GI chart.

There are so many ways to eat a balanced, nutritious diet and it is imperative to performance that the athlete finds the menu items and foods that works best for him yet still maintains this delicate balance of nutrients. With proper training, diet, fluid intake, and timing of energy intake, the athlete will be well-prepared to accomplish their personal marathon goals and maybe even score a PR (personal record)!


  1. Hutchinson A. “The Incredible Shrinking Marathoner.” November 12, 2013. Accessed 05/6/2016.

  2. Schröder S, Fischer A, Vock C, et al. Nutrition Concepts for Elite Distance Runners Based on Macronutrient and Energy Expenditure. Journal of Athletic Training. 2008;43(5):489-504.

  3. Jeukendrup A, Gleeson M. Sport Nutrition: An Introduction to Energy Production and Performance. Human Kinetics, Inc. 2nd Ed. 2010.

  4. Blake, JS, Munoz, KD, Volpe, S. Nutrition: From Science To You – Access. 2nd ed. Boston, MA. Pearson; 2014. E-book, p. 598.

  5. Nelms MN, Frazier C. Cellular and Physiological Response to Injury: The Role of the Immune System. In: Nelms MN, Sucher KP, Lacy K, Roth SL. Nutrition Therapy and Pathophysiology. 2nd ed. Mason, OH: Cengage Learning, 2011: p, 168.

  6. Accessed 05/11/2016.

Balanced Diet

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