The best way to get energy before a workout is to eat easily digestible carbohydrates one to four hours ahead of time, stay hydrated, and consider a moderate dose of caffeine. These three basics account for most of the difference between a sluggish session and one where you feel dialed in. Beyond that, a proper warm-up and a few targeted supplements can push things further.
Eat Carbs on a Sliding Scale
Carbohydrates are your muscles’ preferred fuel source during moderate and high-intensity exercise. The general guideline is 4.5 to 18 grams of carbohydrates per 10 pounds of body weight, eaten one to four hours before your workout. The closer you get to start time, the smaller that amount should be. A 160-pound person, for example, might eat 70 to 130 grams of carbs three hours out, but only 30 to 50 grams if they’re eating within an hour of training.
What you eat matters as much as how much. Foods that are low in fat, low in fiber, and low in protein digest fastest and cause the least stomach trouble during exercise. Think white rice, a plain bagel, a banana, or regular pasta. Whole grain bread, high-fiber cereals, and brown rice are normally healthy choices, but they slow digestion and can cause cramping or bloating mid-workout. Milk products can be problematic too, since even mild lactose sensitivity gets amplified during intense movement. If you’re prone to stomach issues, stick with processed “white” carbs and low-fiber fruits like grapes or tomatoes in the hours before training.
Training on an empty stomach is an option for easy, low-intensity sessions, but it comes at a cost for anything demanding. Fed workouts consistently outperform fasted ones in research: you can sustain higher intensity, last longer before fatigue sets in, and recover faster afterward. Your brain runs on glucose, so focus, coordination, and technical performance all tend to improve when you’ve eaten. If your workout involves heavy lifting, intervals, or anything that pushes your heart rate up, eating beforehand is worth the effort.
Use Caffeine Strategically
Caffeine is the most well-studied performance enhancer available without a prescription. It increases endurance, sharpens focus, and reduces how hard exercise feels at a given intensity. The practical sweet spot is 100 to 200 mg, roughly the amount in one to two cups of coffee, taken about 30 to 60 minutes before your workout. That translates to about 1.5 to 3 mg per kilogram of body weight.
Higher doses (5 to 9 mg per kilogram) also boost performance, but they don’t appear to offer much additional benefit over the lower range, and they’re far more likely to cause jitteriness, a racing heart, or GI distress. Starting low is the smarter play. If you drink coffee daily, you may need to land closer to 200 mg to feel the effect. If you’re caffeine-sensitive, 100 mg or even a strong cup of green tea can be enough.
Hydrate Two Hours Ahead
Dehydration saps energy faster than most people realize. Even a small fluid deficit reduces blood volume, which means less oxygen reaches your muscles and your heart has to work harder for the same output. The American College of Sports Medicine recommends drinking about 17 ounces (500 ml) of fluid roughly two hours before exercise. That window gives your body time to absorb what it needs and clear any excess through urination before you start.
Water is fine for most workouts under an hour. If you’re training longer or in heat, a drink with electrolytes helps, but avoid anything with very high sugar concentration (above 500 milliosmoles per liter), as those hyper-sweet drinks tend to cause bloating and nausea during movement. Skip drinks sweetened exclusively with fructose for the same reason.
Do a Dynamic Warm-Up
Nutrition handles fuel. A warm-up handles delivery. When you move through dynamic stretches, leg swings, bodyweight squats, or light jogging for five to ten minutes, you raise muscle temperature and open blood vessels so more oxygenated blood reaches working tissue. Research on warm-up protocols shows that oxygen saturation in muscles like the quadriceps and biceps increases significantly after a proper warm-up, meaning your muscles literally have more fuel available from rep one.
A warm-up also primes your nervous system. Muscle fibers contract faster and more forcefully when they’re warm, which is why your first set always feels heavier than your third. Spending even five minutes on movement that mimics your workout (air squats before a leg day, arm circles and band pull-aparts before pressing) can make the entire session feel smoother and more energized.
Supplements That Actually Help
Beyond caffeine, two supplements have solid evidence for boosting workout energy and performance.
Beetroot juice is a natural source of dietary nitrates, which your body converts into nitric oxide, a molecule that widens blood vessels and improves blood flow to muscles. The effective dose is about 350 to 500 mg of nitrate, typically found in a single concentrated beetroot shot. Timing matters here: nitrate levels in your blood peak about an hour after drinking, but the form your body actually uses for vasodilation peaks closer to two and a half hours later. Drinking your beetroot juice two to three hours before exercise hits that window. Taking more than double the standard dose doesn’t improve results, so one serving is enough.
Citrulline malate works through a similar pathway. Your body converts it into arginine, which then boosts nitric oxide production. The effective dose is 6,000 to 8,000 mg taken about an hour before exercise. It’s commonly found in pre-workout powders, though many products underdose it. If you’re buying a pre-workout blend, check the label for the actual citrulline content rather than relying on a proprietary blend that hides individual amounts.
A Simple Pre-Workout Timeline
Putting it all together, here’s what a practical pre-workout routine looks like:
- 2 to 3 hours before: Eat a carb-focused meal (rice, pasta, bread) with a small amount of protein. Drink 17 ounces of water. If using beetroot juice, take it now.
- 1 hour before: If you haven’t eaten a full meal, have a small snack like a banana or a couple of rice cakes. Take caffeine (100 to 200 mg) and citrulline malate if you use it.
- 10 minutes before: Start a dynamic warm-up with movements that match your workout.
You don’t need all of these tools at once. Carbs, water, and a warm-up are the foundation. Caffeine adds a reliable boost. Beetroot juice and citrulline are refinements that matter most for endurance work or high-rep training where blood flow is a limiting factor. Start with the basics, and layer in extras only if you feel you need them.