This seems to be a hot topic. Apparently, there is some new research claiming that working out on an empty stomach with increase fat burning. One of the most important things I can every tell you is that anything “NEW” in health and fitness is a bunch of bulls%&t. The human body has not changed for thousands – yes THOUSANDS – of years. We already know what works – sometimes we just do not want to hear it.
NOTE: For my more educated and scientific-minded readers, please do not be offended by my oversimplifications.
I am going to keep this as simple as I can – for it is incredibly complex. Our body uses each of the macronutrients we consume – fats, carbohydrates, and proteins – in slightly different ways. But it uses each of them and the body legitimately needs each of them. Carbohydrates are the primary source of energy – and what provides the most effective immediate energy. Your body needs that energy to partake in physical activity. When that immediate energy is not available, your body must look internally. The fastest source of energy is within muscle – the muscle itself and the intramuscular fat (yes, there is some fat in your ‘muscles’). Does that sound good?
Did you think that your body would immediately go to the fat? WRONG. In fact, the processes required for converting fat into useful energy are actually quite time consuming and require that you sustain activity for a significant amount of time (e.g., more often your aerobic activities).
When to eat
You should eat something within 1 1/2 hours and 45 minutes prior to your workout – a 45 minute window (McArdle, Katch, & Katch, 2005; McArdle, Katch, & Katch, 2010). If you have not eaten, you risk cannibalizing muscle. That sounds good, does it not?
It is equally as important to eat immediately following your workout to refuel your system. Assuming you have worked at an appropriate intensity, your heart rate will be elevated for some time and your metabolism will be roaring – you need to feed this sufficiently.
DO NOT workout for more than 1 hour without refueling (Louks, 2004; Louks 2007). You risk ‘hitting the wall’ and this is the best approximation of we reach glycogen depletion – you need glucose to effectively continue working and drawing from internal energy sources (e.g., fat). Further, I would note that unless you are training to be endurance athlete, there is not benefit to working out for more than approximately 1 hour, anyway!
What if – – –
–you are not able to eat during the 45 minute window? For instance, what if you are a 5:00am gym rat – are you going to wake up extra early to eat? It is unlikely. I am stealing the term ‘shooter’ from my mentor – a concoction of 1 scoop of protein powder, half a bottle of water, and half a bottle of 100% juice. Drink this on your way to your workout and drink throughout until it is gone (and then continue with water).
What to eat
This is debatable – dependent upon specifics of your workout and your personal nutritional needs. I would highly encourage you to consult with a registered dietitian to build the best plan for you. Specifically, seek out an RD with sports nutrition education. I will simply say – eat REAL FOOD. This is the best fuel you can provide for your body – before, during, or after workout. Carbohydrates and proteins are typically a safe choice.
It is important to eat before your workouts – you will be stronger and have significantly more energy at your disposal. And working out without adequate full puts you at risk of doing more harm than good – cannibalizing muscle, diminishing returns, dizziness, fainting, nausea, and all that fun stuff!
Loucks, A. B. (2004). Energy balance and body composition in sports and exercise. Journal of Sports Sciences, 22(1), 1-14.
Loucks, A. B. (2007). Low Energy Availability in the Marathon and Other Endurance Sports. Sports Medicine, 37(4/5), 347-352.
McArdle, W. D., Katch, F. I., & Katch, V. L. (2005). Sports & Exercise Nutrition (2nd Ed.). Lippencott Williams & Wilkins: Philadelphia.
McArdle, W. D., Katch, F. I., & Katch, V. L. (2010). Exercise Physiology: Nutrition, Energy, and Human Performance (7th Ed.). Lippencott Williams & Wilkins: Philadelphia.