What is the likely outcome of prolonged fasting on blood sugar levels?

During prolonged fasting, blood sugar levels typically decrease due to a combination of metabolic adaptations aimed at preserving energy and maintaining homeostasis. Initially, after fasting begins, the body relies on stored glucose (glycogen) for energy. However, glycogen stores are limited and can be depleted within about 24 hours of fasting for most individuals.

As fasting continues, the body transitions from using glycogen as a primary energy source to utilizing fat stores. This process involves gluconeogenesis, where the liver produces glucose from non-carbohydrate sources such as amino acids and glycerol. Although the body works to regulate blood sugar levels during fasting, the overall trend is a decrease in blood sugar levels as glycogen stores diminish and insulin secretion decreases.

Additionally, insulin levels drop during fasting, reducing glucose utilization and prompting glucose production to meet the body's energy demands. While glucagon levels rise to facilitate this production, the end result still tends towards a decline in overall blood sugar levels during prolonged fasting periods.

Therefore, the correct outcome of prolonged fasting is a decrease in blood sugar levels.