Intermittent Fasting Cycles

Intermittent fasting (IF) involves cycling between periods of eating and fasting. During fasting, the body goes through different stages based on the duration of the fast. Here are the general stages:

 

1. Fed State (0-4 Hours After Eating)

 

• Process: Right after you eat, your body is in the fed state. Blood sugar and insulin levels are elevated.

• Main Activity: The body uses carbohydrates for energy, prioritizing glucose from food. Fat storage is more likely during this time.

 

2. Postabsorptive Stage (4-16 Hours After Eating)

 

• Process: The body starts shifting from using glucose (sugar) for energy to stored glycogen (sugar stored in the liver and muscles).

• Main Activity: Blood sugar levels start to drop, and insulin levels decrease. The body begins using glycogen for energy but hasn’t started burning fat yet.

 

3. Early Fasting State (16-24 Hours)

 

• Process: After glycogen stores are depleted, the body begins to switch from glucose to fat for energy. This marks the transition to fat burning (lipolysis).

• Main Activity: Fat cells start releasing fatty acids, which are converted to ketones for energy. Insulin levels remain low, promoting fat breakdown.

 

4. Fat-Burning State (24-48 Hours)

 

• Process: The body is primarily using fat as its energy source. Ketone levels increase significantly, and fat loss begins.

• Main Activity: Ketogenesis (the process of producing ketones from fat) becomes more pronounced. The body starts using stored fat more efficiently for fuel. Muscle preservation is supported through the production of human growth hormone (HGH).

 

5. Deep Fasting State (48+ Hours)

 

• Process: Autophagy, the process where the body cleans out damaged cells and regenerates new ones, is maximized. Cellular repair is heightened.

• Main Activity: Ketones become the primary source of energy. Cellular maintenance, repair, and recycling (through autophagy) are at peak levels. The body efficiently removes damaged proteins and toxins.

 

6. Starvation State (5+ Days)

 

• Process: After prolonged fasting, the body enters a starvation state, where muscle breakdown (catabolism) may begin as the body tries to preserve energy for vital functions.

• Main Activity: The body seeks alternative energy sources, leading to muscle protein breakdown. Long-term fasting can be dangerous without medical supervision.

 

Common Intermittent Fasting Protocols:

 

• 16:8 (Leangains): 16 hours of fasting, 8 hours of eating (usually daily).

• 20:4 (Warrior Diet): 20 hours fasting, 4-hour eating window.

• 5:2 Diet: Eat normally 5 days a week, and restrict calories (around 500-600) for 2 non-consecutive days.

• 24-Hour Fasts: A full 24 hours of fasting once or twice a week (Eat-Stop-Eat method).