Chapter 1: Understanding the Fasted State

Engaging in workouts while in a fasted state can significantly enhance fat burning. After a period of fasting, particularly between 12 to 24 hours, the glycogen reserves in your liver are nearly depleted. But what does it mean for glycogen to be "depleted"? Glycogen consists of multiple glucose units linked together, stored primarily in the liver—a crucial organ for metabolism. Upon consuming food, especially carbohydrates, blood glucose levels rise. Persistently elevated blood glucose can pose health risks, adversely affecting vital organs. In a healthy individual, the pancreas responds to food intake by releasing insulin, a hormone that helps lower blood glucose.

You might be curious how blood glucose returns to normal levels. Insulin facilitates the entry of excess glucose into the body's cells, which is essential for cellular function. For instance, liver cells, fat cells, and muscle tissues absorb glucose and nutrients after a meal, leading to reduced blood glucose levels post-consumption. The liver then converts glucose monomers into glycogen through glycogenesis, a process that stores energy for later use.

During fasting, glycogen can be broken down via glycogenolysis, releasing glucose monomers into the bloodstream to maintain blood glucose levels. This regulation is crucial, as low blood glucose can also be dangerous.

What happens after 12 to 24 hours of fasting when liver glycogen is almost gone? In a healthy person without conditions like diabetes, the body resorts to breaking down fat stores to supply energy and glucose to cells. This process, known as lipolysis, is essential during fasting periods.

For example, if you finish dinner at 6 PM, go to bed at 10 PM, and wake up at 5 AM, you've been fasting for 11 hours. As previously mentioned, glycogen stores typically deplete within 12 to 24 hours, depending on your carbohydrate intake the previous night. A low to moderate carb intake would lead to near depletion at around 12 hours, while a high intake could extend this to 20-24 hours. Thus, the common fasting duration is between 12 and 24 hours.

Continuing with the example, if you start your workout at 7 AM, you're 13 hours into your fast. Assuming a low to moderate carb intake the night before, your glycogen reserves are likely low. If you engage in an intense weightlifting session followed by cardio, what energy source will your body rely on?

The answer is your fat stores. Fat is stored for energy during prolonged fasting or when glycogen stores are low. If glycogen levels are low from fasting, the body must use fat stores to maintain blood glucose levels. Additionally, during intense workouts with depleted glycogen, hormones like glucagon, epinephrine, and growth hormone become more active. All three hormones promote fat breakdown. Intermittent fasting combined with rigorous exercise stimulates growth hormone production, which aids in preserving and building muscle mass, particularly when amino acids are available in the bloodstream.

Video: Do Fasted Workouts Make You Lose Weight Fast?

This video explores whether exercising while fasting accelerates weight loss and discusses the metabolic benefits associated with this practice.

Intermittent fasting serves as an effective strategy for reducing body fat. During fasting periods, the absence of food intake prevents insulin production, which inhibits fat storage. Insulin, being an anabolic hormone, promotes fat accumulation. Therefore, during an intermittent fasting regimen, the lack of insulin secretion allows the body to predominantly utilize fat tissue and glycogen for energy, helping to maintain healthy blood glucose levels.

Furthermore, incorporating exercise into fasting can amplify metabolism and increase lipolysis to meet the demands of physical activity.

However, it's important to note that individuals with certain medical conditions, such as diabetes, may experience disrupted blood glucose regulation. If you have such a condition, it's crucial to consult your healthcare provider regarding the safety of intermittent fasting or any other lifestyle modifications.

Note: I am not a healthcare professional. Always discuss any dietary changes or new regimens with your doctor.

Chapter 2: Benefits of Fasted Workouts

Video: 5 Reasons You Should ALWAYS Workout During a Fast [Burn more fat]

This video outlines five compelling reasons to incorporate exercise into your fasting routine to enhance fat loss and improve metabolic health.