Food to fuel exercise

There's a lot of confusion about eating before exercise. Do all workouts need fuel before? Are some more worthy than others? What should I grab?

​Check out the below for answers to these questions and more.

To begin, consider why you are engaging in physical activity - are you trying to "train" your body? Or are you just "exercising?"

Some see the two ideas as the same, but often the mindset differs. As a result, it changes the perceived role and value of food in movement. 

"Exercise", is the physical activity performed for the effect it produces today - right now. It satisfies the immediate need - burning calories, sweating, getting out of breath. It's about punching the physical clock. 

VS

"Training" on the other hand is performed for a performance goal - moving easier, moving farther, moving faster. Training involves tough days, easy days, and rest with thoughtful progressions and the body's challenge/recovery. It's about improving movement and honoring/respecting the shape needed to perform that movement. 

Simply put, exercise is doing things TO the body. Whereas training is about thoughtful movement WITH the body - listening to the body's voice and knowing when to challenge it and when to honor it.

Often when people are thinking about food and "exercise" the belief becomes, "eat the least amount possible to survive the necessary amount of movement."  Whereas when people "train," it's about optimizing the body as a machine. Under-fueling the body undermines the entire process of movement! 

Let's remember the "point" of training

When you train, you are essentially trying to accomplish 2 things :

• STRENGTH - be able to resist more force. Whether that means picking up your grandchild or a small truck, strength training is about creating muscle and allowing the body to practice key movements in a controlled setting

 

• ENDURANCE - be able to move farther with less effort. Whether that's being able to walk down the hall or complete an Ironman triathlon, you are  strengthening your heart and lungs which thereby increases the amount of oxygen they can take in and circulate to the body, with less effort. It also creates more oxygen receptors in the muscles. 

Side note: Even if you consider yourself in the exercise camp, you are STILL trying to accomplish the above 2 goals. If you're trying to "burn calories with cardio" that is in essence working on endurance. If you are trying to speed up your metabolism, you are trying to build muscle...Bodies adapt better by training (varying workouts higher and lower intensity, incorporating rest, listening to your body) rather than trying to reach a certain # of minutes or calories... 

Both of these goals require you to ...

• Challenge yourself (consistently). When you challenge (not destroy) yourself, you cause you cause little bits of microscopic damage to the part of the muscle that contracted (heart, lungs, biceps, etc). The harder the work (within reason), the more damage that occurs, and the greater the repair/adaptation - thereby building muscle. The body does a lot of this within the first hour of exercise and then continues for the next 24-48 hours. We refer to this time period as “recovery.” If you give your body energy before a workout (food = energy), you are able to work at a higher level thereby increasing the challenge. 

• Help your body repair. Nutrition is helpful with this repair process. When you eat or drink protein (paired with a little carbohydrate and antioxidants) within an hour of the damage, the body does a better job repairing the damage and builds better/stronger muscle. This allows you to workout harder the next time, causing more damage...then repair/adaptation....and the process continues. If you give your body energy (food = energy) after a workout, it has more tools to repair the damage. Not eating after a workout is like asking a builder to fix a roof without a hammer or nail gun. Sure they can use other tools and "get by", but the process will take longer and likely not be as strong compared to if they had the right tools. I'll cover eating after movement in another blog post. 

Question: Do I always need fuel before movement? 

Yup - pretty much. Depending on how long you plan to move and when you ate last, your body still needs fuel to challenge itself. The portion varies greatly depending on your goals and training schedule. Check out the chart below for a little general guidance: 

Question: But I'm not an athlete...do the rules still apply?

I would argue anyone who moves intentionally or with a goal in mind is an athlete.  You may not be competing, but if you're trying to challenge and improve your body, it needs fuel to work it's best.

Question: Won't I burn more calories (or fat) if I go into a workout starved?

I know, it seems counter intuitive to eat if you are trying to lose weight. While I much prefer people focus on moving because it's fun, rewarding, playful, improves mood, improves health, makes you stronger, etc I recognize the only reward some people want to see is on the scale ( :( ).

But here's the deal, even if you're trying to make your body smaller, it's often because you want some of the same training outcomes - increased muscle (metabolism) and the ability to do cardio longer and burn more calories. If you put in minimal fuel because you're scared of calories, workouts not only feel terrible (making you less likely to return for a 2nd round), it also compromises how hard you can work and the results you see.  

Additionally, going into workouts under-fueled because you are restricting what you eat means that your glucose stores are low. If glucose is low, the body is much likely to pull muscle as fuel. If you are losing muscle, you are doing the opposite of training...which means you're burning fewer calories each workout.

​Check out the next question to understand how the body uses fuel during workouts. 

Question: What kind of fuel is best? 

ALL exercise uses energy - but the source changes. Very high intensity exercise primarily uses glucose (aka, blood sugar) as fuel. As exercise becomes longer, the body uses more fat as fuel (but it also uses glucose for the process).

Question: You still haven't answered my question, WHAT AM I SUPPOSED TO EAT? 

Ok so you've noticed I like to talk a lot. If you haven't come to the conclusion already based upon my lengthy explanation, your body works best on glucose during workouts. ​Glucose comes from carbohydrates (to understand "what" carbs are, check out this blog post). 

Exactly what and how much you should eat depends on when you're working out relative to your last meal / snack.

Most exercise (strength and cardio) uses glucose as fuel in one way or another. Glucose (aka blood sugar) comes from starch (rice, potato, pasta, crackers, cereal, flour, bread) and sugar. The body also has stores of glucose called glycogen that it will use if it runs out of glucose. The body prefers to have glucose readily available rather than breaking down glycogen for fuel. 

​Note: The body also uses fat as fuel at lower intensities. BUT that doesn't mean you need to or should workout longer or slower in order to lose weight / burn fat. Changing your workout duration and intensity just to change fuel sources will either leave you under or over challenged.  Do what you love and challenge your body - it will adapt as necessary. 

Situation based fueling

We've talked a bit about why to eat and what to eat,  but now how do you apply it to your life? Consider the below scenarios...

If you workout first thing in the morning...you likely only have 30-60 minutes before you start moving. Ideally you're relatively fueled from dinner (and not starving). If your workout is less than an hour and not that intense, you might be able to get away without fueling morning of. If you're working out an hour or more OR working really hard, grab something that digests quickly (starch and sugar).  Completely fine to add a little fiber / fat / protein, but it should be a small % of the overall fuel to avoid stomach upset.

If you workout in the afternoon...you likely had lunch 2-3 hours before. Technically whatever you ate at lunch should be enough to fuel an hour workout. But you may want to add a quick fuel source if...

• You didn't have starch at lunch (eg, you just ate vegetables + meat) 
• You skipped lunch OR ate lunch >3 hours before your workout
• Your workout is more than an hour

​If you workout after dinner...If you are a late night warrior, it can be tricky to balance food and exercise. Eating a boat load of veggies and meat before a workout is a recipe for misery. Additionally, saving dinner for after the workout may feel tricky. You may consider...

• Break dinner into 2 instances - eat the starch portion and a little meat before. Eat the remaining starch, meat, and veggies after
• Eat an earlier dinner and a refuel snack after

Some follow up questions I get are ... 

• How much am I supposed to eat?  That's not a simple answer. While there are formulas that exist to dose carb, protein, and fat, they are simply starting points consideration. Individual needs vary greatly and can vary day to day based upon workouts (and the rest of your life). My job as a dietitian is to know the numbers and to more importantly, know how to help people adjust them and apply to their unique life. 

 

• So you're telling me to eat a lot of sugar and starch before a workout?  Don't twist my words! My point is that sugar and starch are not evil. They genuinely have a place in performance nutrition. They each have a purpose and a benefit in meals and snacks leading up to a workout, in the amount that fuels your body well. Some people have their best workouts after eating pancakes, while others crumble. 

​ 

• Why not protein / fat in the hour before a workout?  Your stomach needs blood to digest foods - particularly proteins and fat. However when you're training, your muscles ALSO need more blood for fuel and cooling. This creates a challenge for the body - who gets the blood? As a result, people end up either feeling fatigued OR with a stomach ache, particularly if they're trying to workout at very high intensities OR in hot conditions. Examples of challenging foods may be - lots of ts of eggs, yogurt, milk, cheese, bacon, sausage, meats in general, cottage cheese. However,  if you're working out at lower intensities (or have a stomach of steel), it's not as big of a consideration

 

• But won't fiber prevent me from "crashing?"  Isn't it "healthy?"   I'm not saying that anything is good or bad for you. Fiber has a lot of benefits, but eating it takes up a lot of room in the stomach and for some, can cause GI upset for some people (particularly those with IBS working at high intensity). Additionally, foods with loads of fiber often aren't as energy dense so you have to eat a larger portion in order to get the fuel you need. So while a bowl of berries sounds like the "healthier" option, it would take almost 1 1/2 cups of berries to get the same energy from a slice of bread. ​

 

• What about caffeine? While caffeine is an ergogenic aid (aka, it reduces the perceived effort of workouts so you perform better - particularly for endurance activity), it has a bell curve. That means caffeine has been shown to improve performance in small doses, but quickly reduces performance if taken in excess. Additionally, too much caffeine easily cause diarrhea, increase you heart rate, make you jittery, dehydrate, and leave you exhausted. So a cup of coffee or ~150-200 mg can be helpful before, but more may reduce your performance. 

Moral of the story...

There are SO many reasons to eat before training...and virtually zero reasons not to. What you eat and how much you eat depends on the training that you're doing. My job as a dietitian and personal trainer is to help you line up your performance goals with your fuel selection in a way that leaves you energized. 

Stay nourished friends!

Geeking out on food chemistry and macros?
Check out my 3 part series on macros: 
Part 1: Carbs
Part 2: Protein
Part 3: Fat