The purpose of pre-workout nutrition is to give you energy for optimal performance. During moderate-intense workouts 30-90+ minutes in length, blood glucose and glycogen are the main energy sources your muscles depend on.
Both are derived primarily from dietary carbohydrates, with blood glucose being the accessible form for all your tissues to use and glycogen being the stored form. Glycogen is stored mostly in the muscle, ready to be called upon to fuel local contraction, and a smaller percent is stored in the liver to regulate and maintain optimal blood sugar levels.
Pre-workout nutrition concerns itself with topping off blood glucose and glycogen levels in preparation for workouts; perhaps other nutrients depending on how much time you have for digestion.
Fat, Carb, & Protein Metabolism
During rest and light movement, your body uses fat metabolism as its main fuel source. Fat metabolism is a slow process requiring a lot of oxygen though yields more than twice the dietary energy per gram than carbohydrates (fat yields 9 calories/gram whereas carbs yield 4 calories/gram).
Fat metabolism works well in lower intensity exercise as there’s plenty of oxygen to fuel movement. Increasing exercise intensity increases oxygen demand to continue producing energy, to a point where fat metabolism gets overtaken as the primary energy provider.
Glycogen is a part of carbohydrate metabolism. Carbs become an increasingly important energy source as exercise intensity increases. All digestible carbs except fiber are metabolized into monosaccharides (glucose, fructose, and galactose) in your body. In the liver, fructose and galactose are either used for energy with their own metabolic processes or converted into glucose, the more useful and universally abundant molecule.
Glucose in either floats around in the blood as blood sugar for system-wide energy (less than 1%), stored as liver glycogen to regulate optimal blood sugar levels (~20%), or stored as skeletal muscle glycogen as a quick-access energy source for muscle contraction (~80%). These numbers can vary immensely per person, with fit individuals storing much more muscle glycogen when compared with untrained individuals. As exercise continues, all three reserves actively deplete to fuel movement.
As exercise intensity accelerates, the body relies more and more on carbohydrate metabolism to meet energy demands. Carb metabolism is faster, uses oxygen more efficiently in producing energy, and can still occur in the absence of oxygen. Furthermore, red blood cells and brain neurons are unable to use fat metabolism under normal conditions (the brain can use ketone bodies derived from fat metabolism under starvation conditions or no-carb diets). These factors make carbohydrates well-suited for high-intensity exercise.
By using carbohydrates, protein metabolism is spared as an energy source and is put to better use as structural components of your body. Proteins perform an incredible and broad range of functions in your body including immune system, enzymatic function, hormone function, etc. Not to mention enabling your muscles to flex and create movement.
Proteins are made of amino acids, with some amino acids routinely converted into glucose through a process called gluconeogenesis, though this process accelerates when carb and fat metabolism depletes. This occurs either during starvation, extended fasts (e.g. 18-48+ hours), large calorie-deficit diets, or from several hours of sustained intense exercise without carb replenishment. Preventing proteins from being used as a fuel source is one priority of workout nutrition.
By understanding the three primary metabolism pathways your body uses to produce energy from food, we can then uncover how to wield this information to produce optimal workout performance. Now we can wield this information to design pre-workout meals.
What and When to Eat
So carbs provide a quick and reliable energy source for exercise. Fat use diminishes as exercise intensity increases, also taking longest to digest. Muscles get damaged during workouts and the subsequent recovery requires protein to mend the muscles stronger than before. Each macronutrient play vital roles in human physiology though when it comes to pre-workout nutrition, easily digestible carbs reign supreme.
3-4 Hours Before Workout
This is the ideal meal 3-4 hours before workout time. Here you have the most time to digest so a balance of carbs, fats, and proteins can go a long way in providing steady energy.
Macro ratio for your meal is generally ~50-65% carbs, ~15-25% proteins, and ~20-30% dietary fat. This ratio can change depending on the workout type.
- Long endurance and conditioning workouts require a lot of energy so eat more carbs for longer/more intense workouts. If you plan on training hard for 60-90+ minutes, replace dietary fat with carbs while keeping protein the same.
- Strength and muscle training workouts require a bit more protein to support muscle repair and growth. 25-30% protein with 45-55% carbs and 20-25% fats is ideal.
Aim for 6-10 Calories per kg bodyweight. I weigh 74kg currently so my meal is ideally 444-740 Calories. This is a general guide and specific numbers can vary between people.
Also get ~500ml+ of water as there’s plenty of time to process it. Proper hydration is important for maintaining blood volume, regulating body temperature, as well as preserving strength and focus. Even minor dehydration can increase heart rate, making hard efforts even harder. Proper hydration leads to ideal performance.
Complex carbs (starches and fibers found in starchy vegetables, legumes, and whole grains) with plenty of fiber are preferred this far out from the workout. This combination take longer to digest therefore providing a gradual supply of energy as opposed to spiking your blood sugar prematurely.
It’s a good habit to use a food scale to weigh everything and keep track of ratios with food-tracking apps. I personally use Cronometer to track my intake. Doing so will show exactly what your meal ratios are which can be an eye-opening experience. Doing it regularly can help you make better nutrition choices long-term.
Example Meals:
- Chicken, rice, and vegetables
- Oatmeal with fruit, nuts, and a scoop of protein powder
- Burrito bowl — rice, beans, lean protein, veggies
- Turkey or chicken sandwich on whole grain bread with a side of fruit
- Salmon, sweet potato, and greens
- Eggs, toast, avocado, and fruit
1-2 Hours Before Workout
With less time to digest, now is the time to choose lighter and smaller pre-workout meals. ~60-70% carbs, ~15-20% protein, and ~10-20% dietary fat. More carbs with less fat and fiber.
- Lean towards simple carbs this time. Processed grains, whole fruit, milk products, and added/refined sugar digest quickly and provide spikes of energy to fuel your workouts.
- Fat and fiber are reduced as they lengthen digestion. You want your stomach mostly empty during workouts.
Aim for 2-4 Calories per kg bodyweight. Using myself as an example again, 148-296 Calories 1-2 hours before workout.
~350-500ml of water will ensure you’re performing in a fully hydrated state without sloshing around in your tummy.
Example Meals:
- Greek yogurt with berries and honey
- Turkey sandwich on white bread
- Banana with a small amount of nut butter
- Rice cakes with sliced turkey or chicken
- Small bowl of cereal with milk
- Protein shake blended with fruit
30-60 Minutes Before Workout
More of a snack than a meal, pre-workout snack this close before workout consists almost entirely of carbs. ~85-95% carbs, ~0-10% proteins, and ~0-5% dietary fat.
- With carbs being almost the entire focus, go for fast-digesting, low-fiber sources only. Essentially serving as energy spikes.
- Minimal protein as there’s insufficient time for it to digest and provide muscle protein replenishment during the workout.
- Fat and fiber are to eliminated as much as possible as even a little will slow digestion noticeably.
Aim for 1-2 Calories per kg bodyweight. For me this would be a 74-148 calorie snack. 150-300ml of water is good.
Example Meals:
- Banana
- Rice cake with honey
- Small glass of orange juice or a sports drink
- Pretzels
- A few dates or a small handful of dried fruit
- Sports chews/gummies
- White toast with jam (no butter)
For people who rely on caffeine for workout performance, this is the ideal time to supplement. Research objectively shows caffeine can reduce perceived effort of performance, blocks perception of fatigue, and boost muscle contraction. Endurance and high-intensity strength training may benefit greatly. 3-6mg of caffeine per kg bodyweight is the effective supplementation, though lower doses could work with few side effects.
The downsides of caffeine being that it may irritate digestion, cause sleep issues, and produce anxiety. Furthermore, sugar and cream may contribute to weight gain if unregulated.
I personally abstain from caffeine. It only makes sense in my perspective to take caffeine right before a marathon or equivalent level event. I often see people take caffeine too frequently and carelessly as is, taking caffeine to the detriment of their sleep and digestion, so I make the point from abstaining entirely. I rely on my willpower, discipline, and resolve to perform well during my workouts. It’s the cleaner route.
Conclusion/Summary
The purpose of pre-workout nutrition is to prepare your body to meet increased energy demands when it’s time to workout. Having insufficient pre-workout nutrition can lead to faster fatigue or reduced performance. Having excess pre-workout nutrition can lead to bloating and discomfort also impairing performance. The happy middle ground is when the calories consumed are utilized directly and holistically to improve physical well-being.
3-4 hours from workout; a large meal with complex carbs. 1-2 hours from workout; a smaller meal with less fat/fiber and more simple carbs. 30-60 minutes from workout: a small snack made almost entirely of fast-digesting carbs.
References
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- Greiwe, J. S., Hickner, R. C., Hansen, P. A., Racette, S. B., Chen, M. M., & Holloszy, J. O. (1999). Effects of endurance exercise training on muscle glycogen accumulation in humans. Journal of Applied Physiology. https://doi.org/10.1152/jappl.1999.87.1.222
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- Berg, S. (2026, July 6). What doctors want patients to know about the impact of caffeine. American Medical Association. https://www.ama-assn.org/public-health/prevention-wellness/what-doctors-want-patients-know-about-impact-caffeine