The mysterious “fat burning zone” continues to confuse many gym-goers. The theory goes something like this: working out in a “zone” of intensity that is less intense for at least 20 minutes will burn more fat calories than calories from carbohydrate. Is this true? Yes and no, but mostly no. You actually burn more calories from fat right now, sitting still, reading this post, than you do on the treadmill. That is because in the resting state, the body burns a higher percentage of fat calories. As you crank up the exercise intensity, you burn a little less fat per calorie. However, it really comes down to the total number of calories you burn per exercise session — if you want to lose weight.

Here is an example:

Let’s pretend for a moment that you decide power walk for 40 mins on the treadmill. This would burn approx. 5 to 6 calories per minute. After 40 mins, you will have burned 200 to 240 calories. Not bad. Percentage-wise, about 50% of these calories will come from fat, so about 100 to 120 calories.

Now, let’s say you decide to add running intervals to your power walk at a 1:1 ratio, meaning that for every bout of less intense cardio, you do an equal-length interval that is more intense. After 40 mins of this type of intense activity, you will likely have burned between 400 to 450 calories. A bit less fat is burned during intense activity, BUT, you burned more total calories. So, if 40% of those calories come from fat, you will have burned 160 to 180 fat calories!

This was a simple example of how interval training can turn up the calorie-burn. Try adding intervals to your current cardio routine if you want to 1) burn more total calories and 2) burn more fat!

Back in the 90’s, I recall reading the advice that skipping food before an early morning workout forces the body to utilize fat stores for fuel right away. At the time (and not knowing better), this sounded reasonable. I was never able to stick to that “rule,” mainly because I was so dog-on hungry in the morning and would also return from my workout with the jitters from low blood sugar if I didn’t eat beforehand. I ignored that advice, and when I returned to school some years later to complete my BS in Exercise Science, I learned that the body always uses carbohydrate for fuel, and also requires carbohydrates to burn fat. So much for the aforementioned myth.

Here’s the deal: The body uses carbohydrates first. No exception. The chemical reactions that support this energy-making process occur rather rapidly. This is what enables you to run up the stairs in response to hearing a child cry for help. Think of carbs as “fast fuel.”

The process of turning carbohydrate into fuel is called glycolysis. Now, one of the by-products of glycolysis can be sent through another series of much slower chemical reactions called the Kreb’s Cycle. This particular cycle produces fuel for sustained events. Think distance running. Fat doesn’t enter the equation until it is first broken down through a process called beta-oxidation. So it’s not like if you skip breakfast, your body will use fat for fuel instead. It just doesn’t work that way. (Fitness Faux Pas)

My advice: eat a quality carbohydrate, or small snack that has a ratio of 3:1 or 4:1 carbohydrate to protein, and you’ll fuel your workout, as well as enable the fat-burning process to continue (I’d say “begin,” but we’re always burning fat, as long as we’re consuming sufficient calories, of course.)

So let’s recap:

Do we burn fat exclusively if we skip breakfast and then work out? No.

Do we burn MORE fat if we skip breakfast and then work out
No

Do we NEED breakfast (or some form of food) before a morning workout? YES! Emphatically, YES!! (Food is your friend)

The dedicated souls who exercise because they love it are a rare lot. The rest, well, exercise because it is an important step on the road to weight loss. And we all know that weight loss really means, “fat loss.” Am I right? Unfortunately, there is a lot of misinformation about the “fat burning zone,” which leads us to believe that exercising at a particular intensity, above a minimum amount of time, is the optimal “fat burning” place. Not so (and that isn’t necessarily a bad thing). And here’s why…

Like it or not, we all burn a higher percentage of fat calories for energy when we’re sitting on our duffs, than cycling like a feign. That is simply they way our metabolisms are designed. We do burn fat when exercising, but you don’t burn a higher percentage of fat exercising for more than 20 minutes, or at a higher intensity, or at a lower intensity really. The difference is pretty insignificant. But (and this is a big one) – if you burn MORE calories (either at rest, or during exercise), the more total fat you’ll burn.  To burn more fat, burn more calories.

The 3 best fat-burning moves

1.  Exercises that involve the largest muscle groups (glutes and quads), burn more calories. The more muscle mass you have, the more calories you’ll burn at rest, and since you burn a higher percentage of fat in a resting state than during exercise, it makes sense to focus on the large muscle groups first.  Squats, leg presses, leg extensions, lunges, Romanian dead lifts are examples of weight training exercises that target these large muscles.

2.  Interval training burns more calories  than traditional, steady-state endurance training (if duration is the same for both). During exercise, you burn both carbohydrates and fat, but you burn more carbs than fat for fuel. However, the more total calories you burn, the more fat calories you’ll burn.  Here’s a simple example of interval training:  add intervals of 3-5 minutes that are at a higher intensity, then spend roughly equal that time recovering, then repeat. Thirty- to forty minutes is sufficient. Shorter intervals of even higher intensity are fine too – just check with your doctor if you have any pre-existing health conditions.

3. Running and cross-country skiing: these activities burn more calories than most other cardiovascular workouts. Again, the more calories you burn, the more fat calories you’ll burn. The ratio is roughly 60% carbohydrates to 40% fat utilized as fuel during cardiovascular exercise. For example, if you cycled for 30 minutes and burned 200 calories doing so, only 80 of those calories would come from fat. However, if you ran at a 7 mph pace instead, you’d burn roughly 400 calories (depending on your height/weight), and 160 of those would be fat calories!

The exact number you will burn depends on many factors, but you get the idea. To burn more “fat” calories, burn more total calories!