How to Decide Whether You Should Eat Before Working Out

If you’re someone who likes to start your day with a workout, you have probably wondered if you should eat before hitting the gym. If you have ever experienced low blood sugar during a workout and felt nauseous, vomited or were dizzy, you may understand why fasting is not always an option. 

Some swear by fasted exercise, claiming it helps burn more fat, while others say fueling up is essential for peak performance. Both approaches have their place, but your decision should depend on the type and intensity of your workout. 

Remember, nutrition for exercise is not just about energy to do an activity; it also impacts your performance and recovery after the workout.

Read Next: How Special Operations Candidates Should Approach Workouts to Become Stronger

Finding the right mix of food before fitness training is a personal preference and largely depends on how your digestive system handles food, drink and physical activity shortly afterward.

Let’s break down the benefits and considerations of fueling before early morning workouts, especially for those who typically exercise fasted.

When Fasted, Go with Low-Intensity Exercise

Our go-to energy source when we are active is blood sugar and glycogen (the form in which carbs are stored in the muscles and liver). We will burn that first if it is in our body. If we do not have carbs in our diet, then fats, amino acids and lactate will be converted into glucose and stored as glycogen. 

This process, however, is slower and more conducive to less intense workouts or very short, intense workouts.

If your morning routine includes easy-paced jogging, brisk walking, yoga or light calisthenics, working out on an empty stomach is unlikely to cause problems for most healthy individuals. These exercises don’t heavily tax your body’s energy reserves, so you can easily rely on what’s stored from the previous day. Additionally, you may have time for 20- to 30-minute, higher-intensity workouts even when fasted. However, anything prolonged will require effective fueling strategies to achieve optimal results in performance, energy levels and recovery.

Some people enjoy the feeling of lightness and mental clarity that comes with fasted training. Low-intensity, fasted workouts can be a safe choice for those aiming to improve fat utilization or simply prefer a quick start, as long as you pay attention to how you feel and stay hydrated.

Once you start getting lightheaded during workouts, you need to downshift your intensity to a walk or an easy bike ride, or consume some carbs immediately. If your blood sugar has ever crashed during a workout, you know the feeling. Typically, a combination of water, carbohydrates and electrolytes can help alleviate the feeling within five minutes.

Fueling Matters for Longer, High-Intensity Workouts

When it comes to high-intensity or longer workouts, such as heavy weightlifting, sprinting, swimming, rucking, or vigorous calisthenics, fueling beforehand becomes significantly more important. 

These workouts require readily available energy – mostly from carbohydrates – to support performance and prevent fatigue, dizziness or injury. Finding the right mix of food and drinks is best done during these workouts, not on a testing day. Gastrointestinal issues can occur when testing fueling strategies, so determine what works best for you and maintain it as a standard during workouts, graded events or competitions.

Exercising intensely without sufficient fuel can lead to drops in blood sugar, reduced exercise output and slower recovery. If you push yourself while fasted during intense sessions, you might not only feel sluggish but also increase the risk of muscle breakdown as your body seeks energy elsewhere. 

For athletes and fitness enthusiasts seeking to build muscle, enhance speed or optimize endurance, consuming a meal before these workouts is a smart approach.

Common Workouts: What’s Best for Fasted and Fueled Training?

While we are all different and some can do many of these fasted, others prefer being fueled. Here is a list of common workouts and my recommendations for energy, performance and recovery:

Weightlifting

Fueling is recommended. Eating before heavy lifting helps maintain strength, stamina and muscle preservation. Fasted lifting could lead to reduced power and slower gains.

Calisthenics

For light body-weight movements that are routine, fasted training may be fine. If intensity or volume is high, a snack can boost endurance and stamina.

Jogging

Easy-paced jogging can be done fasted by most people. Longer or faster runs, however, will benefit from pre-workout nutrition – not caffeine but real energy in carb form.

Sprinting

Like heavy weightlifting, always fuel before these intense workouts. Sprinting requires quick, explosive energy and fueled performance.

Swimming

Swimming at moderate or high intensity expends a lot of energy, especially if you are skilled at swimming. Non-swimming athletes work even harder in the water and need fuel. A light meal or snack before exercise can help improve stamina and prevent fatigue.

Rucking

Because rucking combines walking with weight, it’s both endurance and strength-demanding. Fueling before is strongly advised to sustain energy and protect muscles. If you are just walking, you might get away with a faster start, but if going for long distances, you may want some backup carbs in that backpack.

Quick Nutrition Ideas: Foods for Pre-Workout Energy

Most fasted situations occur when you're short on time in the morning before your workout starts. If that’s the case, you don’t need to prepare a full meal. Here are some quick options that I have tested that work, are easy on the stomach and provide fast-acting energy:

• Banana or apple with a tablespoon of peanut butter
• A slice of toast with honey
• Greek yogurt with berries
• A few tablespoons of honey
• A small protein shake with fruit
• Granola bar

Try to eat these 30 to 60 minutes before your workout so your body has time to digest and absorb the nutrients. For very early workouts, even half a banana can make a noticeable difference in energy and performance.

Choosing whether to exercise fasted or fueled comes down to your workout type, goals and how your body feels. Fasted training may be suitable for easy, short activities, but when your session is intense or long, a little pre-workout snack can go a long way toward improving performance, energy and recovery. 

Experiment with different foods and timings to determine what works best for you – and remember to check out the Military.com Fitness Section for more ideas on training and fueling strategies.  

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