Fueling Your Workout
Alison Tedrow, Senior Dietetics Student, Iowa State University
Have you ever heard someone say they like to workout on an empty stomach because then they burn more fat? This is one of the most detrimental workout myths out there. The reality is, working out on an empty stomach breaks down muscle instead of building it and will most likely lead to not having the energy to complete a good workout. This is because the body's preferred source of energy is carbohydrates. When a workout is completed in a fasted state the body will use whatever carbohydrates are left, then protein from muscle degradation, and finally fat. Food is fuel, and just like a car can't run without gas, the body cannot run without food. Therefore, proper nutrition can make the difference between a good workout and a sluggish workout. The keys to successfully fueling a workout are meal or snack composition and timing.
What is eaten immediately before a workout, if anything, is an important item to consider because this is what the body will primarily rely on to get through the workout. It is generally considered best to provide a good source of simple carbohydrates and protein. Why? Because carbohydrates are the body's preferred source of energy and simple carbs will be absorbed quickly. However, during a long workout (2 or more hours) consuming a combination of complex and simple carbs would be best so that the complex carbs can fuel the later part of the workout, due to slower absorption. Protein will promote quick muscle recovery and help to minimize damage. Research has shown that supplements that combine carbohydrates and protein reduce muscle damage and soreness because of the response created by both the myoglobin and the creatine kinase in muscle (1). Supplying a pre-workout meal with carbs and protein can be as simple as making toast with peanut butter, mixing Greek yogurt with berries, grabbing a handful of raisins and almonds, or blending a protein shake. Precisely how much one should eat is going to vary by the intensity, frequency, and duration of the workouts. In addition to eating before a workout it is also important to remember to properly hydrate with plenty of water.
Timing of a pre-workout snack or meal is just as vital as what is eaten. The exact best time to eat before a workout is going to vary from person to person so make sure to experiment a little, but generally between thirty and ninety minutes before a workout is going to be best. Eating too close to a workout will cause the stomach to compete with the working muscles for blood to help digest the food, which can cause stomach cramping and nausea. Eating too far ahead can cause the body to run out of fuel before the workout is complete, causing the body to feel tired and fatigued. Not only does correct timing fuel the workout it also can increase lean body mass and increase muscle strength gains during resistance training (2). Now what about those morning workouts? Those can be tricky, but the best option is to eat some combination of simple carbs and protein immediately after waking up so that by the time the workout has begun the body has had adequate time to process the food. If this does not seem like enough time, a bed time snack the night before could also fuel the workout (3).
While both what is eaten and when it is eaten are important, the trick is putting those together. Meal or snack and timing should vary by how close it is to the workout. For example, if a workout is planned for 4 in the afternoon, consuming a substantial lunch 3 to 4 hours beforehand and then a snack approximately 1 hour before should provide sufficient fuel. A substantial lunch would allow the metabolism to continue supporting the body through the day and should include all of the macronutrients: carbohydrates, protein, and fat. An example of a food containing all of the macronutrients could be a turkey and cheese sandwich with mayo. The pre-workout snack should be modeled as discussed above including simple carbohydrates and protein to provide the fuel needed for the workout. However, if time did not permit for lunch until closer to the workout consuming a lighter lunch may end up being the best option. Adjusting your meals and snacks can be easily achieved as long as proximity to the workout and meal or snack composition is considered.
No matter what your exercise plans may be, make sure to also plan your pre-workout nutrition. With good meal or snack composition and timing you will be providing yourself ample energy to have a successful workout. Just remember, if you can't fuel it you can't move it!
For questions, contact:
Carrie J. Leiran, MS, RD, LD
The Nutrition Centres at UnityPoint Health - Des Moines-Des Moines
Baty, J. et al. The effect of a carbohydrate and protein supplement on resistance exercise performance, hormonal response, and muscle damage. Journal of strength and conditioning research/national strength and conditioning association , 21:321-329, 2007. (1)
Clarke, N. Sports Nutrition Guidebook. Champaign: Human Kinetics, 2008. (3)
Cribb, P. J. and Hayes, A. Effects of Supplement Timing and Resistance Exercise on Skeletal Muscle Hypertrophy. Med Sci Sports Exercise , 38:1918-1925, 2006. (2)