As a personal trainer and nutritional consultant, I hear a few questions over and over again. One of the most common ones is what I hope to provide some clarity on today: Should I eat breakfast before I workout? One magazine says one thing, a blog post says another, but what they all promise is faster weight loss. I think this is why it is one of those topics that have been rehashed over and over again for more than a decade. Today I will present to you the scientific facts, some of which we have know a long time and some that are now emerging. Then I will give you my best recommendations. Now you could be one of those people who skips past the middle and jumps right to the punch line; however, I suggest you don’t do that. Just like a good joke is in the telling, my recommendation won’t be very clear if you don’t understand the why behind it. So buckle up and let’s become science geeks together!
Food provides the fuel our body needs to live and exercise. There are three basic macronutrients: protein, carbohydrate and fat. Our body can extract energy from all three sources, and will do so depending on what the demand is. That’s right, it all depends on what you are doing, when you ate last and what you ate. When we exercise, our body selects energy from four sources: muscle glycogen (muscle carbohydrate stores), blood sugar, blood fatty acids, and intramuscular triacylglycerol (1). Carbohydrates are the quickest source of energy. If they are not available or are in too limited of supply, the body will use blood fatty acids and then begin to break down fat for energy. This is a slow, laborious process. And finally, when all else fails, it will use protein, whether floating in your blood stream or breaking down tissue to get it. You read that correctly, your body will eat itself to give you energy. During periods of moderate to high -intensity training, your body needs carbohydrates in order to keep moving. The fat and protein conversion to energy is too slow to keep up. Without the carbohydrates immediately available, your energy will lack and your muscles will underperform. That being said, at low to moderate intensities, the body prefers fat for energy.
If you have eaten before your workout, you will burn more energy after the workout, expending more calories and will absorb your post workout nutrients better (2). However, if you skip breakfast and go right to your workout, although your energy will be lower and you will have to work in low to moderate intensities, you will burn more fat and your genes expression will begin to change, creating a body that may prefer fat for fuel (3). This may sound good, but according to recent research published in Exercise Sport Science Review, this neither leads to increased weight loss nor fat mass loss (4). Therefore, in a fasted state, you will not have the energy to exercise at a high intensity and therefore will burn less calories overall and have a lower chance of burning off that stubborn body fat.
So here’s the skinny of it, both work for different reasons and both can be used at different times for different purposes. Please allow me to explain. There is a time for fasted exercise. That time is for when you are trying to improve the body’s ability to use fat for fuel, not for weight loss, but for performance. This can be beneficial if you will be working out for long periods of time so you want to train your body to use fat as opposed to quickly burned up carbohydrates. Primarily, this will be important if you are a high level athlete, such as a marathoner or long distance cyclist. If, however, you are not training for an endurance event, you should eat some carbohydrate and some protein in the morning before your workout. This will allow you to work at a higher level, burn more overall calories and improve your body’s ability to absorb and utilize the food you eat after your workout (thereby creating the potential for better recovery).
Here are some best practices for pre-workout nourishing:
- Get up a little earlier, as you need to eat the food an hour or so before working out.
- Nourish yourself with healthy carbohydrates and a small amount of protein.
- If you are an early morning exerciser and will only have 30-45 minutes to digest before beginning, be sure to eat foods that are easy to digest and low in fiber.
- Within 20-60 minutes of finishing your workout, eat a complete breakfast with all three macros (fat, carbohydrate and protein).
- Stay hydrated. Drink plenty of water before, during and after your workout. Hydration plays a huge role in stamina both during the workout and recovery after.
Here are some simple pre-workout meals:
- 1 boiled egg white with an orange
- 1 slice whole grain toast with 1 tablespoon peanut butter
- small apple with 1 tablespoon peanut butter
- banana and 1 boiled egg white
- ½ cup low-fat cottage cheese with peach or pineapple slices
- 6 oz plain Greek yogurt with ½ cup fresh or frozen blueberries
- 1 cup prepared Oatmeal with ½ cup berries1. https://riordanclinic.org/2012/04/fuel-sources-during-exercise/2. Edinburgh RM, et al. Pre-Exercise Breakfast Ingestion versus Extended Overnight Fasting Increases Postprandial Glucose Flux after Exercise in Healthy Men. Am J Physiol Endocrinol Metab. 2018 Aug 14. doi:10.1152/ajpendo.00163.2018.3. Yung-Chih Chen, et al. Feeding influences adipose tissue responses to exercise in overweight men. Am J Physiol Endocrinol Metab 313: E84 –E93, 2017. First published March 14, 2017; doi:10.1152/ajpendo.00006.2017.4. Melanson, E.L.; MacLean, P.S.; Hill, J.O. Exercise improves fat metabolism in muscle but does not increase 24-h fat oxidation. Exerc. Sport Sci. Rev. 2009, 37, 93–101.