<em>In addition, both plant and animal cells store energy by shunting glucose into fat synthesis pathways. One gram of fat contains nearly six times the energy of the same amount of glycogen, but the energy from fat is less readily available than that from glycogen.</em>
Fats typically provide more than half of the body's energy needs. Fat from food is broken down into fatty acids, which can travel in the blood and be captured by hungry cells. Fatty acids that aren't needed right away are packaged in bundles called triglycerides and stored in fat cells, which have unlimited capacity. The brain uses glucose and ketone bodies for energy. Adipose tissue uses fatty acids and glucose for energy. The liver primarily uses fatty acid oxidation for energy. Muscle cells use fatty acids, glucose, and amino acids as energy sources.
