Metabolic Flexibility: Why You’re Not Burning Fat and How to Change it

Jerry F. Scarlato
7 min readDec 3, 2019

What if I told you that the bowl of oats that you had this morning was keeping you from burning fat? Or that healthy, whole wheat bagel that you had for lunch? Or even that whole grain, gluten free pasta that you’re making from dinner? It’s all keeping you from burning fat.

Which may not make sense at the moment. After all, aren’t these things “healthy” carbohydrates that allow the body to burn them slowly? And doesn’t that mean that you can still burn fat while eating these slow-burning carbs? Well, not exactly.

You see, to some extent, a carb is a carb. While some forms of carbohydrate or certainly healthier than others, the end product for all of them is the same: glucose in the body. And even though the body utilizes carbs to produce energy (which is why your oatmeal is touted for its energy-producing capabilities), teaching your body to ONLY use carbs for energy production is a recipe for disaster.

Why You Don’t Want to Rely on Carbs as Your Only Fuel Source

The issue is not the type of carbs, per se. The issue is that the body is relying on that carbohydrate intake to produce energy. Which means that, once those carbs are used up, the body has a hard time turning to other sources to produce energy.

As I mentioned, this can be disastrous in terms of keeping you focused throughout the day, perform during your workouts, or simply enjoying time with friends and family. When your main energy source is gone, that’s the time when you get lethargic, unfocused and less productive.

This is also important for fat loss. If you notice, I’m using the term “fat loss” instead of “weight loss”. These are 2 totally different ideas. In short, “weight loss” assumes that you simply want to see the numbers on the scale go down. You don’t care how, you don’t care if you lose muscle, you don’t care if you have to cut off a limb. All you care about is seeing a smaller number the next time you get on the scale.

For “fat loss”, on the other hand, you are intentional about what TYPE of weight you are losing. In “fat loss” you are focused on losing, you guessed it, FAT! And when you lose fat and KEEP the muscle that you have, the body becomes more metabolically sound. Which means that it becomes better at using different sources in order to produce energy, instead of simply utilizing carbohydrates.

This process by which the body can switch the sources of energy production, be that glucose, glycogen stores, dietary fat or STORED fat, has a name: metabolic flexibility.

The Factors That Decrease Your Metabolic Flexibility

As you can imagine, being able to switch to any energy source you want at any given time is advantageous. Not only so you can be more productive in your work, keep pushing yourself during your exercise, or enjoy higher quality time with your kids, but also because it increases your longevity.

That’s partly because when you eliminate the 2 main factors that hinder your metabolic flexibility, the Standard American Diet and Insulin Resistance, your health increases exponentially. Take the Standard American Diet, for instance. As you well know, our diets have developed into a, intake of high-carb, highly processed food-like substances. Because of this tendency for high carb and highly processed foods, when these types of foods go missing, the body craves them (literally, as you well know). Which keeps you down the path of relying on carb-laden foods for energy.

With insulin resistance, the body has a hard time listening insulin, the hormone secreted when you ingest carbohydrates, correctly. Essentially, when you ingest carbs and other foods, insulin is released. And insulin’s job is to “signal” to the body’s cells to “grab” the glucose out of the blood stream. When this signal is broken, glucose levels rise, sending the body into a constant loop of trying to shuttle glucose out of the blood and not being able to.

So, you see, increasing your metabolic flexibility is not only good for your external performance, it’s also necessary for your overall health and longevity. The next question, naturally, is: how can you improve metabolic flexibility? Which is exactly what we’re going to tackle now.

3 Ways to Improve Your Metabolic Flexibility

To begin our search for how to improve metabolic flexibility, it makes sense to start with the 2 main hinderances that keep it at bay. While you certainly won’t fix the Standard American Diet or Insulin Resistance in one big swoop, there are a few important steps you can take to begin to turn them around. So, let’s jump in and take a look at 3 ways to overcome these 2 factors so that you can increase your longevity and improve your metabolic flexibility:

#1) Intermittent Fasting (or IF for short)

I’m positive that you’ve heard of IF at this point. If you haven’t, you must be living under a rock. The main idea behind IF is simple: restrict your eating to 8 hours a day. How does that look on paper? If you’re a person that loves breakfast and can’t pass it up, maybe you eat at 8am which means you’ll have your final meal at 4pm. On the flip side, if you’re not a breakfast eater, maybe you don’t until noon, which means your last meal would be at 8pm. The idea, obviously, is to ONLY eat within your 8 hour window.

Another strategy you can utilize here is a weekly fast. This is one of my favorites because it allows the body to have a single “reset” day each week instead of focusing on eating in that 8 hour window every day. With a weekly fast, you pick one day per week where you go AT LEAST 20 hours without eating, with the goal being a full 24 hours of fasting. This timeframe allows the body to reset itself and find other sources of energy instead of relying on the food you’re taking in.

#2) Carb-backloading

The idea of carb-backloading was popularized by John Kiefer about 10 years ago. In essence, carb-backloading is eating all of your carbs after around 4pm. This is contrary to what most people have been told, which is to eat your carbs in the morning for “high energy” throughout the day.

However, the reason that Kiefer suggests backloading your carbs to later in the day is simple. As you may know, the body has a natural cycle called the circadian rhythm. This is the body’s natural cycle of waking, sleeping and producing and secreting hormones. Part of this natural cycle has to do with insulin sensitivity.

Insulin sensitivity, or the body’s “reaction” to carbs, is highest in the morning for most of us. Which means that the body will more naturally store carbs as either fat or glycogen more easily during the morning hours. As the day goes on, insulin sensitivity decreases. And as it decreases, the body will be less likely to store fat and more likely to burn those carbs up as fuel.

During those day-time hours, of course, the body is relying on all the other sources energy to keep it going. Which is where carb-backloading can be useful. Just be sure to keep your healthy fat intake high during the day to balance out the calorie deficit from pushing your carbs back.

Oh, and as an added benefit, carb-backloading can also help improve your sleep! That’s because, if you ingest proper carbs at night, the body will produce more tryptophan. This amino acid helps in the conversion of serotonin to melatonin, which is the body’s natural sleepy hormone.

#3) Resistance Training

Your muscles are a vast system of untapped potential when it comes to improving the body’s metabolic efficiency. That’s partly because the body stores much of the carbs you ingest as glycogen in the muscles. When you have insulin sensitivity, as discussed above, the cells of the body have a hard time listening to the signal from insulin to scoop glucose out of the blood for storage.

When you partake in resistance training, however, this signal becomes significantly increased. That’s because, when you lift weights, the muscles will want more energy. And it will take the glucose out of your blood stream (I.E. improve insulin sensitivity) and store it as glycogen in order to prepare for the next bout of exercise.

One of the most effective ways to incorporate resistance training is through Metabolic Resistance Training, or MRT. MRT is simply a combination of weight training and high intensity interval training, or HIIT. With this potent combination, not only do the muscles get worked effectively, but the cardiovascular system gets a significant boost as well.

While this isn’t an overnight process, you should certainly take time to consider which one of these strategies you want to implement today in order to improve your metabolic flexibility. In a perfect world, you would incorporate all 3 of these ideas to overcome both the Standard American Diet and insulin resistance. However, be real with yourself and decide which one fits best with your schedule to get started now.



Jerry F. Scarlato

Entrepreneur, Fitness Coach, Performance Specialist, Speaker, Author, cook, endless learner. Check more out: