Why are the brain, heart, and kidneys less affected by starvation than many other tissues?

During periods of starvation, the body prioritizes the maintenance of its most essential organs to ensure survival. When nutritional intake is insufficient, the body breaks down its own protein stores into amino acids to provide energy and preserve the structural integrity of vital tissues.1

The brain, heart, and kidneys are less affected by starvation than other tissues because they are prioritized by the body's metabolic processes. These organs are characterized by an abundant blood supply, which helps protect them from the wasting effects that more severely impact other areas, such as fatty stores, the liver, and spleen. Furthermore, the body employs complex mechanisms to spare essential tissues; for instance, during prolonged fasting, the brain adapts to utilize ketone bodies as an alternative energy source to glucose, which reduces the necessity for muscle protein breakdown and helps preserve vital functions.12