What is the role of adipose tissue during prolonged fasting regarding energy?

Adipose tissue plays a crucial role during prolonged fasting by mobilizing fatty acids for other tissues. When the body is in a fasting state, it needs an alternative source of energy because glucose levels are low, and glycogen stores are depleted. In this scenario, adipose tissue becomes a key player by breaking down stored triglycerides into free fatty acids and glycerol. These free fatty acids are then released into the bloodstream, where they can be utilized by various tissues, particularly muscle, for energy production through β-oxidation.

While other metabolic processes, such as ketogenesis, also occur during prolonged fasting—where fatty acids are converted into ketone bodies for use by the brain and other organs—the primary response of adipose tissue itself is to mobilize these fatty acids. This mobilization ensures that energy is available for critical functions and helps maintain blood glucose levels by conserving available glucose for tissues that primarily depend on it, such as the brain.

In contrast, other options, such as the production of glucose or primarily storing fats without release, do not accurately reflect the active state of adipose tissue during fasting. The emphasis of adipose tissue during this period is its role in releasing stored energy rather than strictly focusing on storage or glucose production.