Fueling Before a Workout

By Lauren Trocchio, RD, LD, CSSD

Last month my nutrition article focused on the big picture of fueling a workout: from daily fueling to which types of runs require pre/post fueling. This month I will hone in specifically on pre-workout/run fueling, including both the timing and content. Things like stomach tolerance, “real” food versus sports food preferences, sweat rates, temperatures, workout timing, and meal timing all require some consideration when determining a routine, and having a practiced routine is key for success.

So we’ll start with our goals of pre-workout fueling.


What is the purpose of pre-workout fueling?

  • To prevent hunger which can impair performance,
  • To “top off” glycogen (carbohydrate) stores in the liver and muscles to maximize workout potential and in some cases prevent hypoglycemia (low blood sugar), and
  • To ensure you start the workout appropriately hydrated.

Keep in mind, even the most kick-ass pre-workout snack won’t accomplish all of these goals if you aren’t fueling well on a regular basis. It may act like a band-aid, but chronic under- or poor quality fueling will leave you hanging on by a thread. Which leads us to a discussion of timing….


If you really think about it, an endurance athlete is almost always in a pre-workout fueling state. (The same could be said for recovery, but we’ll talk about that later.) So while most folks really only consider what you consume in the 15-30 minutes leading up to a workout as “pre-workout”, we’re going to really look at what you are having in the 15 minutes to 24 hours leading up to it (depending on the length and intensity). This is of particular importance to endurance athletes doing multiple workouts a day or back to back long training days.


In general a dinner of quality carbohydrates, lean protein, healthy fats, and vegetables is an appropriate guideline. If you’re facing a tough workout in the morning (greater than 2 hours or something high intensity), then a dinner higher in carbohydrates is in order. This can vary by individual, but a good general guideline is proportionately half of your plate being made up of carbohydrates. The United States Olympic Committee has nice visuals describing plate differences between hard, moderate, and easy training days.

If your workout will be in a hot environment or you are typically a heavy or salty sweater, this is also a good time to start thinking hydration status. Choosing a dinner higher in salt (adding extra to your plate, using soy sauce, having soup, etc.) can contribute to your body retaining more fluids and thus starting the workout with a better hydration status. You can also incorporate a high sodium sports drink.

Not sure if you are a salty sweater? Good indications are salt rings on your clothes after working out or salt flaking off your skin once sweat dries. You may also always crave salty stuff after a workout.


The athlete’s plate mentioned above is again a good general guideline for meal consumption 3-4 hours prior to the workout start. In terms of carbohydrates this is usually about 1-2g/kg of body weight. For a 150lb woman that might look like a large baked potato and a banana (in addition to protein, vegetables, and healthy fats).

Avoiding high fat meals (like fried foods) and high fiber items may help prevent any stomach problems that typically arise. Fat and fiber are slow to digest, thus consuming them surrounding a workout can exacerbate the already slowed digestion caused by blood flow diverting from the gut to the muscles. Choosing starches (such as pastas, rice, potatoes, corn) may help provide a more sustainable source of energy, which may be of even more importance if not consuming fuel during the workout.

Fluid intake should really be tailored to the individual (monitoring urine color throughout the day and aiming for pale yellow is a start), but a general guideline is 16-20 oz of fluid in the 3-4 hours leading up to a workout. Again, salty sweaters can benefit from including more salt with this meal or adding an electrolyte beverage to the mix.

Fall into the early morning workout category? Aim for a smaller 15-30g carbohydrate snack first thing, such as 8-16oz sports drink, a small banana, or a piece of toast. You can also focus on the night before meal as discussed above.

Additionally, there may be some benefit to completing some workouts “low” (ie without pre-workout carbohydrate fueling). Ideally this is only occasionally practiced prior to low intensity, shorter duration workouts – routinely completing endurance training or high intensity activities with low carbohydrate stores can contribute to an increased stress response, reduced immunity, and poor training adaptations.


If you did a good job at your previous meal, you may not need much of a snack at this point. If you sense some hunger arising, or have a longer workout planned and/or won’t consume fuel during the workout, it’s a good idea to consume a mostly carbohydrate snack at this point. Aiming for 0.5-1g/kg body weight is the general guideline, so our 150lb woman may need a large banana or ½ peanut butter & honey sandwich. Avoiding high-fat and fiber items is even more important at this point, but the gut is trainable. Small amounts of protein (5-10grams) are fine. While things like peanut butter are predominantly providing fat, a small portion such as 1 tbsp may be well tolerated and very satisfying after experimenting with timing.

Now is another opportunity to get in more fluids and electrolytes as needed. This is even more important if you don’t plan to consume fluids during the workout. An additional 8-12 oz over the 30-60 minutes prior to starting can ensure hydration is in check. Watch for overhydrating – indications may be clear urine or an overly full feeling or sloshing in your stomach.


Any fueling surrounding a workout should be practiced, practiced, practiced. It really needs to mimic your fueling plan for a race – try whatever foods or sports foods you plan to have on race day in as similar a manner as possible. Keep in mind the nerve factor, too. You may have a stomach of steel or it could be topsy turvy come race morning, so be certain you have some meal and snack options that “sit” well.

Stay tuned next time for info on fueling during a workout!

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