Why and When You Should Eat Before The Gym

By Derek Howes on Nov 4th, 2009 in Articles, Nutrition | Permalink

One thing I find a lot of people get confused about, is when to eat. Specifically when to eat before and after the gym. The science behind it is pretty simple so I will do my best to help you understand both when you should eat and why.

We’ll go ahead and start with when you should eat before the gym. Many people wonder “is it a good idea to eat before the gym?“. Absolutely. As to what you should eat, how much, and how soon, that all depends a lot on what you are trying to do. In a mass building phase you will want to eat more before the gym. My recommendation is 40-50 grams (160-200 calories) of carbohydrates and 20-30 grams (80-120 calories) of protein 90-120 minutes before the gym. In a cutting phase I usually opt for about half of that, 25 grams (100 calories) of carbohydrates and 15 grams (60 calories) of protein. Obviously depending on your individual needs or what your diet calls for, you may want to intake more or less. This is just  the base I go by and what I usually follow (what has worked well for me). Working out for longer than ~90 minutes, doing lots of cardio, and high intensity training are examples in which you may want to add more calories to your pre-workout meal.

You’re probably wondering why you should eat 90-120 minutes before instead of ten minutes. Well to keep it simple, it takes the body about six hours to digest fat, three hours for protein, and two hours for carbs. Kind of get where I’m going? Our gut gets very active when digesting food, thus using more blood supply than normal to digest the food. We need that blood supply while exercising. When the body is trying to do both at once, it will not do either of them “great”. Unless you are eating something that is fast digesting or a liquid, I don’t suggest eating a “meal” that soon before the gym. I also suggest not adding fat (good or bad) to your pre-workout meal. It takes twice, and in some cases three times as long to digest. That’s the short answer on why you should not eat fat. I’ll post and article in the future that goes over fats in detail (when you should eat them and why).

Now you may be asking yourself “but why do I need to eat before the gym?“. I’ll tell you why. As you exercise your body’s main fuel source is carbohydrates that have been stored in your body (known as glycogen which is stored in the muscles and liver). Although some fat is burned, it’s main energy comes from glycogen stores. When glycogen stores become depleted (usually with-in 45 minutes-2 hours depending on intensity/other conditions it could even be sooner) it will look elsewhere for energy. Yes the body will look towards fat for energy, but fat cannot be converted into glycogen. Fat can be converted into ATP (the energy compound inside cells that power muscular contractions) but not glycogen, hence why it is so hard to lose fat. However, protein can be converted into glycogen, which means you will be burning muscle for energy (doing more negative than good).

Eating before the gym will give your body a readily available source of energy. Before carbs turn into glycogen it enters our bloodstream in the form of glucose. If our glycogen stores become low or depleted, our bodies will use glucose for energy. In some studies, the body would spare the glycogen and use the glucose for fuel first. In other words, you have not one source of fuel, you have two. If you’re driving a car in the middle of no where and are low on gas, wouldn’t it be helpful to have a second tank?

If you find yourself getting fatigued at the gym try upping your carbohydrate intake in your pre-workout meal or try taking in a liquid carbohydrate just before you workout. In more than a few studies researchers have found that taking in a liquid carbohydrate right before working out provided higher energy levels and increased strength.

Use this as a base:

• 4 hours before: You can have a normal sized meal with fat, protein, and carbs
• 2-3 hours before: Smaller than normal size – lighten up on the fat
• 60-90 minutes before: Lighten up on the protein as well as the fat
• 15-60 minutes before: Eat fast digesting carbs/liquid

Note: While eating is important, water intake is just as important. Make sure you hydrate before, during, and after the gym.

I will be following up this article with “When you should eat and why after the gym” shortly.

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