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Practical Guidelines for Fueling and Nutrition

Navigating nutrition can be a confusing minefield. Here are some simple things to look out for.

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If there is one thing I would like to ingrain in you, it is the ability to differentiate between fueling and nutrition. Whenever I talk with athletes on the grand topic of nutrition, I begin here. I find that distinguishing between the two concepts can remove some of the emotional baggage from fueling during and after training and provide a clear, simple framework for all of the other decisions you need to make about food. Eating the right thing at the right time is key for athletes, even if one of the goals is improved body composition. Focusing on the number of calories consumed might be the correct approach for an overweight, inactive person, but it’s a short-sighted strategy for athletes who are actively training. Both the rules around nutrition and the individual’s needs are very different.


The calories and hydration consumed just before, during, and immediately after exercise constitute fueling. The goals of fueling are to

  • Optimize performance during the training session
  • Allow proper recovery after the training session (thus setting up the next session)
  • Facilitate self-control and high-quality food choices throughout the day by diminishing the cravings that occur as a result of poor fueling
  • Limit metabolic stress associated with athletic starvation

The fueling window begins 30 minutes prior to a training session and extends throughout the session and 2 hours beyond the time when it ends.

It’s important to have an appreciation for what you are trying to achieve with calories and fluids during the fueling window. The correct mind-set will help you go about the task of fueling with a sense of purpose. All calories taken in during the fueling window are consumed to support training performance and recovery.

My definition of fueling is performance-driven, and for good reason. I don’t want you to think about fueling as a means of supporting good health. I also don’t want you thinking about body composition or weight management during your fueling window. Good health and better body composition begin with proper eating management. Get your fueling right, and you open the door to a cascade of good things both for your sport and for your life in general.

It is important to acknowledge that the best sources and types of fuel are highly individual. I would never endorse a single sports product as the answer to every athlete’s fueling needs. That said, here are some general guidelines.

Pre-workout fueling. You need to take in some calories 30 minutes prior to training to help establish fuel reserves for longer endurance sessions. This is perhaps most critical if you are training first thing in the morning because even shorter morning sessions are beneficial for lowering cortisol levels, which are high first thing in the morning. The optimal fuel source will contain some protein with a little carbohydrate and a high-quality fat. In general, you want to avoid anything that spikes your blood glucose immediately prior to training.

Fueling during training. Here the key to effective fueling is little and often. Any session longer than an hour should include fueling both to help promote performance during the session and to lower the deficit and stress created by that session after it is over. Most, and some would say all, of these calories should be from carbohydrate, typically a glucose/sucrose combination. However, extended-duration or low-intensity training can absolutely be supported by “real food” options that include plenty of protein and fat. Your ability to effectively absorb calories during exercise is greatly diminished because the blood that typically helps absorption is busy shuttling oxygen and other nutrients to the working muscles and cooling the skin. To overcome this diminution, you need to dilute the calories with hydrating fluids and take in smaller quantities of fuel at regular intervals. Use high-quality fluids, not just water, to prevent dehydration and the reduced blood volume that induces fatigue. Choose a very-low-calorie drink with a little sodium added to help absorption. Your caloric intake, combined with effective hydration, will ensure that you achieve the goal of training intensity and caloric-deficit reduction. The table below details basic guidelines for how much to take in and how often. Keep in mind that there will be some variance among athletes.

CALORIES 3 to 4 calories per kilogram of body weight per hour (3–4 kcal/kg/hour)
HYDRATION 10 to 12 milliliters per kilogram of body weight per hour (10–12 ml/kg/hour)
FREQUENCY Every 7 to 20 minutes from the start of training until the end

TIP: Sessions under 1 hour do not typically require fueling during the workout, but post-training fueling remains a critical component of overall success.

Fueling immediately after training. We want to “turn off” the stress of training immediately after the session, and your post-session fueling is a huge help in this. Making protein the primary post-training fuel will stunt the cortisol response of training and help begin the resynthesis of muscle tissue (the recovery process). Within 15 minutes of the end of your session—every single session—you should aim to consume 15 to 20 grams of protein. Combine protein with carbohydrate, as the carbohydrate will be used to replenish your depleted carbohydrate (glycogen) energy stores. Many athletes get these calories from a shake or drink, simultaneously fueling and rehydrating, but if you gain these calories from real food, be sure you also drink plenty of water.

Fueling with a post-workout meal. The immediate intake of calories after training is focused mainly on stunting cortisol and beginning the initial replenishment of glycogen, but the job is not yet complete. Eating a post-workout meal replaces the depleted calories and promotes the recovery process. This meal should come from high-quality real food that includes protein, carbohydrate, and fat. Eating this meal within 90 minutes or so of your training session should prevent hunger cravings later in the day. In the 90 to 120 minutes following your workout, your metabolic rate is still elevated, and your absorption of carbohydrate is higher than it will be for much of the remainder of the day. In addition to a post-workout meal, you will want to continue the effort to restore your hydration status to a normal level, but outside actual training, tap water will suffice.


The calories and hydration consumed during the remainder of the day make up your nutrition—typically breakfast, lunch, dinner, and snacks. The primary purpose of nutrition is to support a healthy life. This is where you gain the building blocks of a high-quality diet: the vitamins, minerals, and other advantages associated with good eating. Your choices around nutrition do not directly affect the performance of a single training session, but good nutrition choices support training by

  • Boosting your global health profile—lowering the risk of disease, maintaining a strong immune system, and supporting good energy and sleep patterns
  • Replenishing depleted resources from your training, such as vitamins, minerals, and macronutrients
  • Contributing to optimal body composition
  • Assisting in the recovery process by repairing and strengthening tissue, tendons, and ligaments
  • Promoting good daily energy levels

Keep in mind what you are trying to do with the calories and fluids taken in during the nutrition window, and the proper actions are more likely to flow from there. All calories that you take in should provide a foundation for good health and a strong immune system while also meeting your needs for energy and body composition management. Great athletes are built on a foundation of good health.

For athletes who need to improve body composition or lose weight in order to improve their performance, the nutrition window is the time during which it is safe to slightly reduce calories. This will work only as part of an effective fueling strategy. Mistakes in fueling lead to the downfall of many hardworking athletes seeking to improve body composition. Poor fueling and the subsequent cravings for subpar food choices during the nutrition window make for a pretty miserable existence. In fact, poor fueling may well be the culprit in the poor relationship that many athletes have with eating in general.

Guidelines for a Sensible Approach to Nutrition

Eat a good breakfast. I have never seen a successful eating plan that includes restriction early in the day. This is a good time to take in any starchy carbohydrates you may eat as well as plenty of protein and fat. Breakfast is the bedrock of a day of good eating.

Hydrate for energy. Support your daily energy with the regular intake of hydrating beverages. Avoid sugary sports drinks; instead opt for water, tea, or even coffee.

Eat your fruits & veggies. An essential source of vitamins and minerals, fruits and vegetables should be well represented in every meal. Simply put, I have never seen anyone get fat from eating too many fruits and vegetables.

Embrace the fat. Many of us grew up hearing that fat would make us fat. I sometimes wish that this macronutrient could be given a different name without the negative connotations. Fat is essential to good health, supporting the immune system and overall well-being.

Proteins are your athletic building blocks. Each meal should include a portion of high-quality protein.

Get carbs from fruits & veggies rather than other sources. This is not a rule, but it is a good guideline for the nutrition window. Many of your carbohydrates can come from highly nutritious vegetables and fruits rather than from starchy sources such as bread or pasta.

Warm up in the afternoon. Drink a warm beverage in the middle of the afternoon to help raise your metabolic rate, which naturally dips around that time. You will feel more alert and be less inclined to reach for the low-quality, sugary foods.

Eat often & snack plenty. If you are following the above guidelines, you will need to eat plenty and often to support your training load and maintain energy and caloric balance. Nutritious snacks play a big role, and remember that all snacks should include some protein.

Don’t diet. As an athlete, you should never diet to lose weight. Instead, create positive habits that yield long-term results. Athletes who go on crash diets seldom have success over the long term.

Recover at night. The best evening snack will include 15 to 20 grams of protein (for example, a nonfat Greek yogurt) to maximize recovery during sleep. Eat a little snack about 30 minutes prior to bedtime, and sleep like a baby.

Don’t count your calories. I have yet to have an athlete succeed with long-term athletic performance and/or weight management by keeping strict account of caloric expenditure or intake. It is a dangerous and distracting game for the training athlete, and the negative emotional attachments to food that arrive with this rigid approach certainly outweigh any positive control gained. Focus on habits, not numbers.

Adapted from The Well-Built Triathlete by Matt Dixon with permission of VeloPress.

The Well-Built Triathlete

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