Metabolic Flexibility: How Shifting Carbs Improves Metabolism, Energy, and Health

Metabolic flexibility refers to the body’s capacity to switch between utilizing various sources of energy as fuel in an effective manner. This is frequently viewed as a sign of wellness and vitality. A higher degree of metabolic flexibility exists when the body can utilize alternative energy sources to glucose. Shifting carbs can boost energy and improve your metabolism.

The capacity to utilize alternative energy sources besides glucose, such as fat and ketones, is a crucial component of metabolic flexibility. The body can enter a state known as ketosis when it can successfully use fat as an energy source. This is a natural process that can lead to an increase in energy and improve overall health.

Metabolic Flexibility: Why it is important

Imagine your friend Rhonda flexing for having superior keto numbers, saying she’s metabolically flexible. Why does it matter? Well, metabolically flexible people, or we could say fat-adapted people can use fats to fuel their bodies. This is important for metabolic health, affecting factors like glycemic control and insulin sensitivity.

Being fat-adapted means you won’t experience a quick energy drop after a few hours of fasting. The body can take and use your fat to keep your energy at medium. Your brain can work on cleaner energy, thus resulting in increased mental capacity. Your ability to lose fat is enhanced, and hunger cravings are incomparably lower now.

Benefits of Using Fat as Fuel

The term “metabolic flexibility” describes an organism’s capacity to modify its metabolism in response to shifts in the availability of nutrients.

Your body needs to be able to access the energy stored in your muscles and fat cells when you are running a marathon. To utilize the nutrients from your lunch to fuel your brain and other organs. When you’re sleeping, your body needs to be able to tap into stored energy to keep all of your vital systems running smoothly.

Having a flexible metabolism is like having a multi-functional machine. It implies that your body can utilize any accessible fuel source, be it fat from the avocado you munched on as a snack or glucose from a sweet snack. It powers your challenging workout, but also your cognitive tasks at the desk.

Overall, metabolic flexibility is important for maintaining good health because it allows the body to efficiently use a variety of nutrients as energy sources, giving you the energy you need to live your life to the fullest.

Fun Fact

Being fat-adapted gives you a leg-up on energy, fundamentally. Anytime sugars are not available, not around – you can still feel energetic. It’s these windows of fasting or skipped meals, or travel that we can use fat to fuel our bodies.

How Shifting Carbs Affects Metabolism


Shifting to a low-carb diet can result in a lower metabolic rate, at least on paper as it seems it can reduce thyroid hormone levels. Isn’t that bad for your weight loss, isn’t accelerating metabolism what we seek, to burn more calories? Hmm, sure, it’s just that keto makes you more efficient at producing energy, hence why you need lower amounts of it. In most cases, BMR drops on keto, but the ability to burn fat increases, which is kinda what we want.

But other research shows low-carb diets actually increased energy expenditure in people in the range of around 200 calories daily. (1)

The ketogenic diet has proven effective in improving metabolic parameters like weight, glycemic control, and lipids in overweight or obese people, potentially reducing the mortality rate associated with metabolic dysfunction. (2)

Burning Fat

Lowering your carbohydrate intake can help your body utilize fat more efficiently as an energy source. When you eat carbs, they are converted into simple sugar (glucose), which is then stored as glycogen in the muscles and liver. Any extra glucose is converted to fat and stored in fat cells after your glycogen stores are full.

When you reduce your carbohydrate intake, your glycogen stores become depleted, which means that your body needs to use fat as an energy source. This process, known as lipolysis, releases fatty acids into the bloodstream, which can be used by muscles as an energy source. (3)

Since low carb-diets are loaded with fat, it’s crucial to take into account what type of fat is eaten. You can’ fuel on bacon, margarine, and salami expecting to improve your cholesterol.

LCHF diets generally lead to a slight increase in LDL, but the net gain is positive as HDL increases and triglycerides are reduced. (4)

lchf benefits

Insulin Sensitivity

Lowering the amount of carbohydrates you consume can increase your insulin sensitivity, which is crucial for keeping your metabolism in good shape. A hormone called insulin helps to regulate blood sugar levels and stores extra glucose as fat or glycogen.

When you consume a lot of carbohydrates, your body makes more insulin to maintain stable blood sugar levels. But, over time, this may result in insulin resistance, as insulin struggles to detect and transport glucose to muscle or there isn’t enough insulin secreted.

This can lead to health issues like type 2 diabetes. Reducing carb intake can help improve insulin sensitivity, allowing the body to use glucose more efficiently for energy and improve metabolism.

Studies show that low-carb or ketogenic diets can reduce fasting glucose levels, improve glycemic control and improve insulin response (sensitivity). (5) (6)

Boost Energy – How Keto Improves Mitochondria Function

The ketogenic diet can significantly impact the function and energy-producing capacity of mitochondria through a metabolic state called ketosis. During ketosis, the body transitions from primarily using glucose as an energy source to utilizing fat stores, specifically in the form of ketone bodies, as an energy substrate.

The mitochondria, the cell’s primary site of energy production, can utilize ketone bodies through the process of oxidative phosphorylation, which is more efficient than the process of glycolysis that occurs during glucose metabolism.

Furthermore, the ketogenic diet has been shown to stimulate an increase in the number of mitochondria within cells through a process called mitochondrial biogenesis. This further enhances the body’s energy-producing capacity. (7) (8)

The mitochondria play a huge role in vitality, energy, and longevity. Ketosis relies on fat oxidation, which is powered by mitochondrial respiration. This creates small amounts of ROS (radical oxygen species) stimulating something called mithormesis. It’s the small ROS amounts that trigger positive changes and improves resilience in humans. (9)


The ketogenic diet can enhance energy production by providing an alternative, more efficient energy substrate in the form of ketone bodies and increasing the number of mitochondria through mitochondrial biogenesis.

Shifting Carbs for Metabolic Health

Low carbohydrate diets are often used to help manage weight and improve health. There are several potential benefits to following a low-carb diet, including:

Disclaimer: It’s important to note that the potential benefits of a low-carb diet will depend on an individual’s unique needs and medical history. It is always a good idea to speak with a healthcare professional before starting any new diet.

Glycemic Control

Low-carb diets can help to improve glycemic control in people with type 2 diabetes. This is because reducing carbohydrate intake can help to lower blood sugar levels and reduce the need for medications that lower blood sugar. (6)

By doing so, we give our insulin time to recharge and reset. It’s often the case that after the keto diet, when people get back to a regular diet, they’re able to use glucose more efficiently. Keto resets this machinery that utilizes sugars and improves the process of energy creation.

Insulin Sensitivity

Low carbohydrate diets may also increase insulin sensitivity, making the body better able to use insulin to control blood sugar. For those who have insulin resistance or prediabetes, this may be advantageous as it may assist to delay the onset of type 2 diabetes.

But it’s not just insulin sensitivity. Although insulin can recognize and transport glucose better, keto works its way on other factors that relate to better metabolic health. These include an improved cholesterol profile, as it increases HDL and lowers glycated hemoglobin levels (HbA1c). (10)

Weight Management

Low-carb diets can aid in weight loss by decreasing hunger and boosting feelings of fullness. This can lead to a reduction in calorie intake and can contribute to weight loss. Low-carb diets may also have other beneficial effects on weight-related health markers, such as reducing levels of triglycerides and LDL cholesterol.

1 molecule of fat generates 100+ ATP molecules
1 molecule of glucose generates 36-38 ATPs

Fun Fact

Fat is more satiating and longer-lasting than carbs. Partially, that’s explained by the superiority in calorie count, as each gram of fat has 9 kcal, while carbs stay at 4 kcal per gram. But it’s also the fact that 1 gram of fat takes way longer to be metabolized and burned for energy, and will produce way more ATP compared to carbs.

low carb high fat

Carb Cycling for Metabolic Flexibility

Carb cycling respects eating a regular carb-heavier diet at certain periods, then taking some time off of carbs where you enjoy a low-carb or ketogenic diet. While the latter is trendier, the point is really to make your body use fat for fuel. Keeping that in mind, there are other ways this can be achieved, such as fasting, keto breakfast, less frequent meal, and so on.

Keto can be a bit too restrictive and may come with some negative side effects. For those that don’t plan their life around their diet, or want an easier ride but similar benefits, low-carb high-fat will do it. Keto is not a long-term, standard diet – at least not for the average population. It’s more of an intermittent diet, a cycle diet. We call it a reset diet because it’s exactly what it is. It’s resetting the machinery that utilizes glucose, so we can use it more efficiently later.

The benefit? The main one is energy maintenance, or energy stability – not experiencing those sugar crashes or energy drops as frequently. Brain health and improved cognitive function are there, as ketone-fueled brains have higher mental clarity and capacity, but not speed. Also, long-term health and vitality heavily rely on healthy metabolic functions.

Fun Fact

Keto is not a performance diet, It’s an adaptative one. Whether you seek higher energy or better athletic performance, keto can help. But not during the competition (life), but before it. It’s the adaptation to not having sugar that makes us use sugar better. It’s just like taking time off of caffeine to improve your focus.

Tips for Improving Metabolic Flexibility

To maximize your body’s metabolic flexibility and improve your overall health, incorporating these six tips into your routine can do the trick:

  • Keto Breakfast
  • Carb Cycling
  • Black Coffee
  • 16:8 Fasting
  • HIIT exercise
  • Monitoring

Ketogenic breakfast: A breakfast high in healthy fats can and no sugar can prolong the time of your sugar-fasting window. This improves metabolic flexibility by allowing the body to shift into fat-burning mode. The best keto breakfast foods to include are eggs, avocados, and nuts in your breakfast.

Carb cycling: Switching between periods of high and low carbs intake, also known as carb cycling, can help improve metabolic flexibility. It allows the body to alternate between burning glucose and burning fat for energy.

Black coffee: Drinking clean black coffee is kind of the perfect drink for this. Compounds like caffeine and cholinergic acid found in it additionally stimulate fasting, while giving you a good punch of energy.

Intermittent fasting: Fasting helps you reduce the frequency of glucose ingestion, prolonging the time you’re in a fat-burning mode. It’s very similar to keto on the metabolism in that regard. Fasting can improve glycemic control, insulin sensitivity, and increase fat oxidation.

HIIT exercise: High-intensity interval training (HIIT) like short sprints, heavy intensity on the bike, pushing sled, or skipping rope are all great ways to use up glycogen and improve cardiovascular health. HIIT has been shown to improve insulin sensitivity and increase fat oxidation.

Glucose monitoring: Regularly monitoring blood glucose levels can help to identify patterns and trends in glucose metabolism, which can inform strategies for improving metabolic flexibility. This can be done using a glucose monitor or by having regular blood tests.


Metabolic flexibility is the ability to switch to an alternative source of fuel, so from glucose to fat. Fasting, ketogenic or low-carb diets, HIIT on black coffee, and less frequent meals are some ways to achieve it. It improves metabolic health by affecting glycemic control, weight loss, insulin sensitivity, and cholesterol profile. Also, it can improve brain health, cognition, and mental capacity when the brain uses fats for fuel. Energy boost and energy stability are one of the main benefits, preventing sugar drops and energy crashes.

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