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Is It Ok To Fast Before Completing A Fat Loss Workout?

I've heard so many stories that when you exercise on an empty stomach, such as first thing in the morning, you can target more fat to burn off during your workout. This leads to the question, does working out while fasting actually help you burn more fat? Or is just a wise old tale?

As a personal trainer, I would recommend that no one runs or completes a workout without adding some kind of fuel. Just because you are using fat as fuel, doesn't really mean that you are burning more fat when you exercise. When you're talking about fat burning, it's really about calorie expenditure (ex. calories in, calories out), not about the type of energy that the body uses during a workout.

Let's explore more on the topic...

Fasted Workouts

Interestingly enough, a study that was conducted in 2019 (Wallis & Gonzalez) found that when individuals fast overnight then complete an aerobic exercise (running, biking, etc.) that it actually increases fat utilization, improved lipid profiles and enhanced metabolism signals and overall decreased caloric intake throughout the day (Wallis & Gonzalez, 2019)

Although, the studies are not long term, so I'm curious to see if fasted workouts actually continue to see the results they found in their study. This 2019 study may look promising, but there is also a large body of research that does recommend proper fueling. Most of the recommendations suggest carbs before a workout, especially for athletes.

I've also read other studies that have been published in the National Strength and Conditioning Journal that states that the amount of calories that you burn is the same during cardio, regardless if you ate or if you are in a fasted state.

This text was interesting because it also suggested that if you do workout in a fasted state at high intensities, it can affect your protein stores, by reducing around 10%. This is extremely important to keep in mind, especially if you are trying to build muscle.

When I was working out in a fasted state and trying to build muscle a few years ago, I had noticed that I wasn't building muscle the way I wanted to. Yes, I lifted. Yes, I increased my weights almost every week. Yes, I increased my protein. But, my muscles never really got bigger like I wanted. Sure, I had lost fat. A LOT of fat, but my muscles were never toned. I got to the point where I had to face the fact that I was depriving my body of the fuel that it needed to build proper muscle when I fasted before a workout.

"As a general rule, if you burn more carbohydrate during a workout, you inevitably burn more fat in the post-exercise period and vice versa."

It's so important to be able to fuel your body when it needs it. For example, if you skip a meal, or a snack, your body won't be able to work as hard as you want it to. This might hinder your progress on your fat loss workout program.

You actually burn fewer calories than if you had eaten before your workout. I cannot stress enough, that fueling your body is so important and it can affect performance, muscle building and even weight loss goals.

Benefits of Eating Before Exercise

Each of us are different, and each of us may have a system that works for us. If you don't, you maybe wondering what works for you, and that is okay - keep trying and you soon will find one that works for you too!

You might be lifting without eating breakfast in the morning, you might be doing a bit of cardio, you might even be swimming at your local gym. Whatever your system is, you should be watching for signs that your body needs fuel to complete really challenging workouts.

Here are some of the benefits to eating before working out:

  • Avoiding low blood sugar. If you experience low blood sugar, it can make you feel dizzy or even nauseous. If you already have a pre-existing condition, this makes it 10x's worse!

  • Boost recovery and strength gains

  • Be able to have longer stamina and have a more intense workout

I can say that even as a personal trainer, I can recommend eating before a workout...but that doesn't always mean that it works for everyone.

If you feel your best early in the morning before breakfast, go ahead and hit up the gym for a workout. But, if you are noticing a decrease in stamina, performance for feeling at all sluggish, you might want to re-evaluate your eating habits.

You might want to think twice if you are just skipping meals altogether because you think that you might be burning more fat. Everyone is different and what works for one may not work for the other.

My brother, who has been a seasoned lifter for over 13 years can go longer distances and lift more if he doesn't eat in the morning before his workouts. I however, found that I have to at least drink a protein shake and a glass of water before I do anything fitness related. My sister has to eat carbs before a workout otherwise she feels sluggish.

You may need to experiment what works for you, but whatever you choose try to make sure that your body has time to digest the food that you are eating before a workout. Try to choose something that is light and simple and maybe low on fiber.

Pre-Workout Snack Ideas

There are so many pre-workout snacks that you can choose from to help fuel your workout. Here's a list to help get you started:

  • Apple with cheese

  • Banana or any other type of fruit

  • Energy bar or gel

  • Fruit smoothie

  • Greek yogurt with fruit

  • Oatmeal

  • Sports drink (Propel or Gatorade)

Learning how to complete exercises with proper form is so essential to building the body you want. Weather you are a seasoned gym goer, or a newbie, we have tips and trick for everyone on their fitness journey.

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Wallis, G., & Gonzalez, J. (2019). Is exercise best served on an empty stomach? Proceedings of the Nutrition Society,78(1), 110-117. doi:10.1017/S0029665118002574

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