During short-term starvation, most available fuel molecules are catabolized to provide energy for metabolism rather than being used as building blocks for growth and repair, a trade-off that is hormonally regulated by

The endocrine system, or hormonal system, is made up of glands that produce hormones. Hormones are chemical messengers that travel through the bloodstream to organs, skin, muscles, and other tissues. They tell the body what to do and when to do it.