How To Fuel For Your Activity Level

Get enough fuel for your activity to see the results you want.


By Heather Caplan, R.D.


You’ve probably heard that you can’t out-train a bad diet, or that it’s better to “eat to run” than “run to eat.” All true! It’s essential to fuel your activity level adequately in order to see any improvement in physical fitness performances such as more strength or endurance. Dietary choices can significantly help or hinder your exercise routine.

There are three levels of exercise as defined by the Center for Disease Control and Prevention (CDC): sedentary/light, moderate, and vigorous. The general definitions of each are as follows: 

  1. Sedentary/Light: General daily activities such as grocery shopping, commuting, household chores, etc. The CDC clarifies that these “don’t count towards the guidelines” of suggested minutes of exercise per week. 
  2. Moderate: Generally aerobic* activity that works up a sweat! You’re able to talk (conversational effort), but not too easily. Some examples given include walking at a brisk pace, water aerobics, tennis, a relatively easy bike ride, and some yardwork (e.g. mowing the lawn). ( *Aerobic is defined by your heart rate zones; you could measure this by wearing a heart-rate monitor and consulting a personal trainer to define your “zones.") 
  3. Vigorous: You’re “breathing hard” and “heart-rate has gone up a bit.” It’s unlikely you could comfortably carry a conversation, or at least not for long! Some examples include: running, swimming laps, biking a hilly route, or playing basketball. 

How you fuel for your exercise depends on what level you’re working at, especially for moderate and vigorous activities. In some cases you may even need to be fueling during your workout, as our body generally only stores enough sugar to carry us through 60-90 minutes (you can build up this endurance with training). By consuming adequate calories and nutrients, both before and after exercise, you may increase your stamina and overall performance! If you chronically under-fuel, you may find yourself losing motivation, feeling fatigued, and having a hard time making it through your normal workouts. 

Before your workout: Choose a snack proportional to your exercise. 

If you plan to workout for an hour or more, you’ll need adequate carbohydrates (i.e. sugar) to provide your muscles with energy. Calorie needs* vary by age, gender, and body-type, but generally a snack within the 100-300 calorie range is sufficient. If you’re exercising around a mealtime, a meal of 300-500 calories would be more appropriate. 

Consume your meal or snack 45-90 minutes prior to exercising to allow for digestion (snacks: 45 minutes, meals: 60-90 minutes). Avoid consuming anything that may cause some digestive distress such as high-fat or spicy meals. You’ll learn more about this with trial and error! 

During your workout (>60-75 minutes): Provide sugar and electrolytes to your muscles as-needed! 

Again, exact calorie needs will vary, but if you’re exercising for longer than 60-75 minutes, you’ll need some extra fuel. Consuming simple sugars will help sustain your energy levels and maximize your performance, eventually fostering improved endurance. Mix water with electrolytes to hydrate your muscles, and consume fuel every 30-40 minutes. 

Some options include: 

  • Dried/Raw fruit (e.g. dates, bananas) 
  • Sports nutrition products 
  • Fruit and nut bars 

After your workout: It’s important to refuel! This is especially true if you’ve exercised longer than an hour (> 60 minutes). This helps the muscles restock sugar storage so that the next time it’s needed, it’s available! If you don’t adequately refuel, eventually that muscle storage taps out and fatigue sets in. Workouts begin to suffer because there’s nothing to pull from! 

Within a 30-60 minute window consume a meal or snack proportionate to the workout. Again, calorie needs will vary significantly by age, gender, sport, and length of exercise (time). In general, it’s best to consume carbohydrates mixed with protein to facilitate muscle tissue repair and growth as well as refill energy stores! 

Some ideas include: 

  • Peanut-butter and banana sandwich on whole-wheat bread 
  • Smoothie made with Greek yogurt and fruit 
  • Scrambled eggs with a baked sweet potato 
  • Egg sandwich on a whole-wheat English muffin 
  • Rice and beans 
  • Trail mix with a piece of fruit 

The list goes on! Again, the most important thing to remember is the essential mix of carbohydrates and proteins, and to be aware of your personal calorie needs. 

Most importantly, remember that your body requires fuel to keep going! We don’t expect a car to run on empty, and the same should be assumed of our muscles. How and when to fuel adequately for weight maintenance will depend on your activity level (moderate or vigorous) and time, along with a few other factors. It may take some trial and error to figure out which fueling foods work best for you! 

*Disclaimer: Consult a sports dietitian or nutritionist to see what calorie ranges you should aim for to facilitate both improved performance, health, and weight maintenance. 

Heather Caplan is a registered dietitian and running coach based out of the San Jose, CA area. She’s usually training for a marathon, traveling, teaching or practicing yoga – or all of the above! You can find her life anecdotes or work with her over at

Running Shoes Photo Credit: Roman Prishenko/; Drinking Photo Credit: Meg Wallace Photography/;  Sandwich Photo Credit: ZEF/