Are you metabolically flexible?
You know that there’re are many types of flexibility that can help you in life, but here’s one you may not know about – metabolic flexibility. We all know someone who can eat and eat and never seems to gain weight. It seems unfair, doesn’t it? It’s like this person has retained the ability to eat carbs and fats like an ever-hungry teenager without gaining weight. The ability to do this depends on something called metabolic flexibility. Why is it that most of us must worry about how carbs and fats will affect our weight – not to mention waistlines? The answer is simple. We can no longer use our stored body fat for fuel, which means we’re metabolically inflexible. When we’re metabolically inflexible, we’re more likely to feel tired, extremely hungry, irritable and brain-fogged. What then is metabolic flexibility? “Metabolic flexibility is the ability to respond or adapt to conditional changes in metabolic demand,” according to the Journal of Cell Metabolism. It’s the body’s ability to adapt and use whatever fuel is available to it, i.e., to switch from using carbs or fats as fuel sources when fasting, fed, exercising or resting.
If we’re metabolically flexible, our insulin levels rise when we fast and then decline after we’ve eaten. The longer we fast, the more our insulin levels decrease. And when our insulin levels are low, our bodies burn fat to get energy. So, what happens when we exercise? The crossover concept comes into play. If we exercise at low-to-moderate-intensity, we enhance fat burning, while high-intensity exercising promotes carb burning. Each of us has a different crossover point at which we shift from mainly burning fat to burning carbs. Metabolically inflexible people start burning mostly carbs instead of fat early on, which makes it difficult to lose weight because your body rarely burns stored fat. So, how can you become metabolically flexible?
Increasing metabolic flexibility
Exercising will increase your metabolic flexibility more than anything else because it increases the body’s demand for energy and glucose to replenish what our muscles lose. According to The American Diabetes Association, “a single bout of moderate-intensity exercise can boost glucose uptake in your cells by 40%.” You can also vary the intensity of your exercise to burn more fat. Just make sure you don’t exercise so hard that you pass the crossover point and shift from burning primarily fat to carbs. Another way to force your body to burn more fat is to fast. Most of us only go a few hours a day without eating except when sleeping. When you reduce your calorie intake, you lower your insulin level. And when your insulin is low, you burn more fat to get energy. This increases your metabolic flexibility and helps you become fat adapted. Fat adaptation is a long-term metabolic adjustment to ketosis, a state in which your body burns fat for fuel instead of carbs and is said to decrease cravings, increase energy levels and improve sleep. People who are highly metabolically flexible and are fat-adapted find it easier to recover from high-calory meals. Their weight might go up for a day or two after, but it will drop when their bodies process and digest the food. Remember the people I mentioned at the beginning? The ones who seem to eat whatever they want without gaining weight? It’s because they’re metabolically flexible and fat adapted. While several other factors are involved in this process, one, in particular, plays a crucial role – Leptin resistance.
Leptin is a hormone we produce in our fat cells. One of its primary jobs is to signal our brains to use our fat stores for energy, which is key to metabolic flexibility. Leptin resistance occurs when cells in the hypothalamus no longer recognize leptin signals. When that happens, the brain thinks there’s a shortage of food coming in and believes we’re starving. Then, your brain will do all it can to compensate for what it perceives as a food deficit. It will take everything you eat and store it as fat instead of using it for energy, which compounds the problem. Your brain is preparing for the “perceived” coming famine, even though there isn’t any famine, which can make it nearly impossible to quell cravings and eat correctly. Leptin resistance is one of the most common reasons we gain weight and can’t shed it. To become metabolically flexible and start burning fat for fuel, you must correct leptin resistance. And incorporating intermittent fasting into your lifestyle is a great way to do this.
Intermittent fasting restricts food for a period each day – usually 12-16 hours – and allows you to burn enough fat to use for energy while releasing a level of toxins that your body can handle. In fact, intermittent fasting along with cyclical ketosis (going in and out of ketosis weekly) is one of the fastest ways to increase metabolic flexibility. It allows your body to get used to using whatever fuel is available and prevents your system from panicking whenever one source of fuel (glucose, glycogen or fat) isn’t available. The takeaway is that there’re benefits to shifting between different eating styles to achieve overall health and metabolic flexibility. But don’t forget to incorporate other aspects of a healthy lifestyle, such as exercise, quality sleep, eating nutrient-rich whole foods, drinking water and managing stress.