Eating While Working Out

Hey everyone ~ It's Nicole again with another bit of nutrition info for Boulder Sports Performance!


Last post I talked about eating before working out. Now let's address nutrition while you are working out.

The biggest determining factor as to whether or not you should eat or drink something while you work out is how long you will be exercising.

For an exercise session that is < 1 hour, you probably do not need to eat or drink anything during that time. (This excludes plain water, which can be consumed if desired.) Your body probably has enough fuel on board to get you through your workout, barring any recent fasting or sickness.

If you are going to be exercising for > 1 hour, the story is different. The first thing to remember is a review from last post – eat or drink what you know your body can handle. Don’t force yourself to eat just because I said you should! Getting sick during a race certainly isn’t going to help you finish faster.

During exercise that lasts > 1 hour, your body is going to use primarily carbohydrates and fats for energy. As your workout gets more intense, you will use more carbohydrate and less fat (and vice versa). Everyone has limited amounts of carbohydrate stored in their bodies to use for energy, while everyone also has enormous amounts of energy stored as fat in their body. Don’t be offended – I’m not calling you fat! Let’s look at this closer:

Even a 70kg (154 lb) person who is considered very lean at 10% body fat has 7kg (15.4 lb) of body fat. Each pound of body fat contains 3,500 calories. So…. (15.4 pounds x 3,500 calories/pound) that means that this person has 53,900 calories of fat stored in his body! Therefore, we have truly do have enormous amounts of energy in our body stored as fat. If this person ran 5 miles, they would burn around 500 calories, so he/she still have plenty of stored energy left over.

Given this example, we can concentrate on consuming primarily carbohydrate while we are exercising for > 1 hour.

It is recommended that 30-60 grams of carbohydrate be consumed each hour, which is 120-240 calories (the range is based on body size). In addition, it is best to space this out and eat or drink something with carbohydrate every 15 minutes, remembering that if you can’t handle this much or this frequent of carbohydrate consumption, scale it back to what your stomach can handle. For example, I usually don’t eat or drink any carbohydrate until the 2nd hour of exercise – my stomach just can’t handle anything during the 1st hour.

So what is 30-60 grams of carbohydrate? Let’s take a look:

**Product Amount Grams of carbs

Gatorade (original) 8 oz 14g
Gatorade (G2) 8 oz 5g
GU (1 packet) 32 g 20-25g
Clif Bar (1 bar) 68g 42-46g

You can see that it is relatively easy to get enough carbohydrate from common sports drinks, bars, and gels on the market. Some athletes will prefer a drink or gel + water, while those engaging in longer sessions, such as day-long hikes or adventure races may opt for something more solid, such as a Clif Bar. Ultimately, it’s up to you, but if you are going to exercise for > 1 hour, your body would probably benefit from some carbohydrates!