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Fats Burn in A Carbohydrate Flame.

 

I just used everyone’s two “enemies” in one sentence: fats and *whispers under his breath* carbohydrates. I know, I said it. Awful.

 

It’s the biggest misconception in the fad diet industry currently, seconded only by intermittent fasting, that carbs are your mortal enemy. I’ve explained why this isn’t true adnauseam, and I’m tired of repeating myself on that. So what I’m here to explain today is how the body actually burns fat. We’ve all heard of the fat burning zone, seen it on equipment, and probably want to burn some body fats- myself included (I’ve not been great about my nutrition lately.) What does this mean though? Is there a zone that I will burn my tum tum away and all will be righted in the kingdom of summer season? Nope.

 

First up, if you need a refresher on the fuel systems in the body there are essentially 4- phosphocreatine, anaerobic glycolysis, aerobic glycolysis, and aerobic lipolysis. All four are consistently working in your body to give you energy- that is, if you’re feeding them. When properly nourished, all systems are a go and are all working to make you go. During the first bit of exercise we use mostly phosphocreatine. Then it transfers after a short amount of time to the carbohydrates stored in the muscles for the anaerobic (without oxygen) glycolysis. Then we go into largely utilizing aerobic systems after a while, and that requires both carbs and fats. If you want a better explanation of that then go find my blog about the fuel systems.

 

Ok, your brush up on the energy pathways is complete. Back to the matter at hand: when and how do we burn fat stores. First and foremost, the way we burn ANY stored energy is to create a need for it. That requires using the energy that’s already floating around, ready to be used. I already mentioned we have some glucose, or carbs, that’s ready to flippin GO waiting in the muscle for it’s moment to burn. After we burn through that, then we get to aerobics, longer systems to produce energy, and fat metabolism for energy. That’s what you see on the treadmill, right? This is our “fat burning zone” so we are burning through our fats like Sherman (I’m from the south) going through Atlanta. Again, nope. Sorry my friends, that is totally not the case. At the beginning of exercise (remember how I said we are using all the systems simultaneously, just relying on one more than others) we are utilizing free fatty acids that are already bee-bopping in the blood stream. Once we go long enough to get into aerobic zones, we have already used those guys up and are ready for our next quick source of energy which is glucose. Now, if we stay in a lower intensity of exercise then we will use more fats than glucose, but this is not your best bet for a few reasons.

 

The reason is simply what I started out with- fats burn in a carb flame. We HAVE to be utilizing some sort of carbohydrates to burn fats- period. Fats burn in what’s called the krebs cycle, but so do carbs. So the intensity has to be enough to require breakdown of carbs and long enough to need fats as an energy source. Basically, remember how I said you have to create a need for it? Well, if you’re just going low intensity the whole time, yeah, you’re using mostly fats but the total amount of calories burned in general is also less. To quote my textbook “expressing energy derived from fat as a percentage without consideration of total energy expenditure is often misleading.” (Exercise Physiology, 8^th edition, Powers et al.)  Also, again we have to create the need for fat stores to be broken down- so it has to be long enough and intense enough to release those stores to create free fatty acids to burn in that carb flame. Your tummy isn’t just digesting what’s on top of it, it’s a whole thing. Also, it is important to note that a person with a diet higher in fat will burn more fat and a person with a diet higher in carbs will burn more carbs, yeah, but again your total expenditure will be lower and unless you’re a marathoner then higher utilization of fats isn’t necessarily a great thing.

 

So toss your low carb diet its causing your body to work at a lower rate, slowing down the amount of energy you could be burning. You’re 20 minutes on the elliptical at a “fat burning” zone is better than nothing, but right next to it. It requires an intensity and duration to be able to utilize fats in general, and you have to create a deficit for the body to release that good ol’ stored energy we know as adipose tissues (or body fat). In short- yeah, you’re burning a higher percentage of fats at lower intensity, but as you are burning much less calories overall you’re not burning as much body fat as you could be. Sorry to ruin something else for you in my blogs.

 

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