In the human body, two major organ systems participate in relatively “long distance” communication: the nervous system and the endocrine system. Together, these two systems are primarily responsible for maintaining homeostasis in the body . Briefly, the endocrine system uses hormones rather than neurotransmitters to communicate and manage metabolism. It is slower to respond than our nervous and immune systems but it longer acting  . The pancreas, kidneys, heart, adrenal glands, gonads, thyroid, parathyroid, thymus, and even fat, are sources of hormones .
The endocrine system works in large part by acting on neurons in the brain, which control the pituitary gland (Brian). Brian is always monitoring and testing our blood so when he senses increases stress the pituitary gland is activated. This activation secretes factors into the blood that act on the endocrine glands to either increase or decrease hormone production. If we’re stressed the signals the liver to release sugar so we can react instantaneously to imminent danger. This is what’s known as a feedback loop, as it involves communication from the brain to the pituitary gland to an endocrine gland and back to the brain . The endocrine system is very important for the activation and control of basic behavioral activities, such as sex; emotion; responses to stress; and eating, drinking, and the regulation of body functions, including growth, reproduction, energy use, and metabolism .Endocrine cells that line the gut produce hormones that communicate directly with the brain and play a significant role in weight management .
When we’re suffering mitochondrial dysfunction as well as the effects of natural aging, decreases in estrogen, progesterone, and testosterone (all linked to the dopaminergic and serotonergic pathways) can result in weight gain, mood changes, and decreased interest in sex [33. 34]. This is also a factor with synthetic hormones such as those used for birth control. These medications can interfere with the absorption of nutrients in the gut microbiome, deplete serotonin levels (which contributes to depression), and increase cortisol levels which negatively affects appetite, sleep, sex drive, and food preferences [33, 34].
Don’t hesitate to discuss any concerns you may have with your primary care provider or endocrinologist who may consider thyroid tests to screen for imbalances. Endocrinologists are experts in treating diseases associated with hormonal systems, ranging from thyroid disease to diabetes mellitus .