Enhanced Autophagy

Diving Deep into the Phases of Fasting

Intermittent fasting has become a popular way of eating, especially over the last 5 years. It’s simple, convenient, and effective for losing and maintaining weight. The human body is built for fasting. It efficiently stores fat and can last day or weeks without any calories at all. If you haven’t already, read my previous article on the Intermittent Fasting diet:

The Least Important Meal of the Day

This article won’t be rehashing the same talking points. Instead, it will go into greater detail on the benefits of fasting. The benefits go beyond the ease of restricting calories. Let’s begin.

Fasting occurs in 4 major physiologic phases:

• Fed State - When you eat, the body absorbs the nutrients. This causes insulin to be released which transports glucose into the cells. Extra sugar is stored as glycogen. Ghrelin (hunger hormone) is decreased and leptin (satiety hormone) is decreased. This phase lasts for a few hours after eating.

• Early Fasting - This phase begins after the fed state ends and lasts about 12-18 hours. Insulin declines and he body converts the stored glycogen into glucose to be used for energy. Glycogen is stored in the liver and muscles and carries a lot of water so you may lose water weight in this phase. During this phase lipolysis also begins where the body breaks down triglycerides for energy. Amino acids are also converted to energy.

• Fasting - The next phase begins after the early fasting phase (usually 12-18 hours) and lasts for 2 days. The body is completely out of glycogen stores at this point. The body has to go looking for energy sources. It breaks down proteins and fat stores, creating ketones which are used for energy. Once this occurs you are officially in ketosis.

• Long-term Fasting - This is sometimes called the “starvation state” as it is the phase your body enters during an extended fast. There is very little glucose left in the body so insulin continues to fall. A small amount of glucose is made via gluconeogenesis which nourishes the brain. The body continues to make ketones and use them as the primary source of energy.