Just because you’re working hard, that doesn’t mean you’re working smart. I see it every day. People come into the gym and hop on a treadmill for 30-60 minutes and then head over to the weights to do their resistance training. Even though my initial reaction is to walk up and smack them in the back of the head, the reality of the matter is this: How would they know any better? After all, for years I’ve heard fitness enthusiasts say that if you do your cardio first, you’ll burn more fat during your weight training, making your weight training an extension of your cardio. Let’s look at why this is about as true as pharmaceutical companies saying they’re more interested in your health than your money. The goal here will be to save some people a little wasted effort with their cardio endeavors.
We’ll start out by looking at how your body uses the food you consume for fuel. Keep in mind that, in this article, I am talking about individuals whose bodies are operating in a generally balanced manner. I write books that teach people how to look at their own specific body chemistry and figure out how their body is operating. Some individuals are all jacked up and have a hard time processing fats, while others have a difficult time processing glucose. But generally speaking, this article is a good guideline of how fuel is used while working out.
You may have heard that you will burn more fat doing cardio on an empty stomach. The truth is that you will actually burn more fat during cardio if you have depleted your body of carbohydrate stores. You can eat proteins and dietary fats without affecting the way your body burns fat. In other words, you could eat some eggs, chicken breast, or even a protein shake without any carbs in it and still burn the same amount of fat during your cardio session as you would if you did that cardio on an empty stomach. However, if you ate an apple or a piece of bread before your cardio, you wouldn’t be able to burn as much fat.
When you eat carbohydrates, your body can store them as glycogen in your liver and wait for your body to use them as fuel. When performing an aerobic activity, like walking or running lightly on a treadmill, your body has the option of using glycogen stores or fat stores. The problem is that your body won’t normally use any fat stores until your glycogen stores are used up. In contrast, during anaerobic exercise, like weight lifting, your body can only use glycogen as fuel. So here’s how it plays out. Studies have shown that it can easily take 29 minutes of cardio to burn your glycogen stores. So if you start your workout with 30 minutes of cardio, not only did you burn fat for a whopping one minute, but you also depleted your body of the fuel it needs (glycogen) to do your resistance training. Now, in order to manufacture glucose (glycogen) during your weight training session, your body may actually break down muscle tissue to use as your fuel. You could end up losing muscle instead of gaining. To make things simple, if you do your weight training first, you can use your glycogen stores as fuel. Then, when you move over to your cardio, you’re right where you want to be… with depleted glycogen stores, giving your body the opportunity to burn stored fat as a fuel source.
I like to see clients do their resistance training for 45-55 minutes and then walk at an easy, steady pace for 20-30 minutes. This way, that easy walking is prime fat burning time. A five to ten minute cardio warm-up before your resistance training is great. But if you want to be one of the cool kids, do your fat burning cardio work after your resistance training.
By T.C. Hale