Hormones, Appetite, & Weight Gain
Hormones are chemical substances produced by organs of the endocrine system and secreted into the body to influence metabolic activity. In response to external or internal stimulation, hormones enter the bloodstream, identify and attach themselves to target cells, and increase or decrease the rate of normal metabolic processes. Hormone secretion is regulated through inherent negative feedback mechanisms, which act by inhibiting further hormone release when the desired effect has been produced. The primary organs of the endocrine system include the pineal gland, hypothalamus, pituitary gland, thyroid and parathyroid, thymus, adrenal glands, pancreas, ovaries, and testis. Secondary organs of the endocrine system include the heart, kidneys, stomach, and adipose (fat) tissue. Cellular metabolism, reproduction, sexual development, sugar and mineral homeostasis, heart rate, and digestion are a few of the many processes regulated by the endocrine system.
Although there are many endocrine organs and hormones with seemingly unrelated effects upon the body, they entire system functions as one and each organ/hormone will influence the production and efficacy of the other endocrine organs/hormones. In other words, endocrine dysfunction or hormone imbalance at any point in the entire system has the power to cause widespread damage that can have a catastrophic effect upon health.
There are a few specific hormones with which we must become familiar if we are trying to live a happier, healthier, and more active life – insulin, cortisol, leptin, and ghrelin.
Insulin and Blood Sugar Management
In the context of diet, performance and health, the hormone of primary importance is insulin and it’s role in blood sugar management. Insulin – a hormone produced by the pancreas that regulates the metabolism of carbohydrates and fats – promotes the absorption of glucose into skeletal muscle where it is used for the short-term production of energy or fat tissue where it can be accessed later in the absence of “fresh” energy.
In a healthy body, carbohydrates are broken down into glucose causing the concentration of sugar in the blood stream to rise. As blood sugar rises, the pancreas spits out a proportionate amount of insulin to help move that glucose out of our blood and into our muscles and fat. As insulin moves sugar out of the blood, blood glucose return to normal and the body goes on about its business. However, problems arise when the body is unable to properly move glucose out of the blood stream, which may contribute to the development of glucose metabolism disorders such as hypoglycemia, or low blood sugar, and hyperglycemia, or high blood sugar, also known as diabetes.
Hypoglycemia is often the first stop in developing a full-blown glucose metabolism disorder and is characterized by dramatic drops in blood sugar that occur in response to the consumption of sugar and other highly refined carbohydrates. Such substances generate large spikes in blood sugar that encourage an equally large release of insulin by the pancreas. Insulin moves the sugar out of the blood and glucose levels return to normal. However, when the body is frequently exposed to large doses of refined carbs and sugar, the pancreas may start pushing out disproportionately large amounts of insulin, which move too much glucose out of the blood and force blood sugar levels well below base line. Low blood sugar levels can produce a family of physically and psychologically uncomfortable symptoms such as anxiety, confusion, irritability, hunger, shakiness, weakness, and fatigue.
If hypoglycemia is left untreated it often progresses into hyperglycemia, chronic disorder of carbohydrate and fat metabolism develop as the body becomes insensitive to the effects of insulin. In response to the consumption of highly refined carbohydrates such as sugar and flour, wild fluctuations in blood sugar and insulin may lead to insulin resistance, a condition in which the body becomes “numb” to insulin preventing sugar from moving into muscles or fat and contributing to chronically elevated blood sugar. Insulin resistance increases the risk of muscle loss, fat gain, inflammation, and biological degradation, all of which exacerbate blood sugar mismanagement and contribute to the development of full-blown diabetes. Untreated or poorly treated diabetes increases the risk of heart disease, stroke, kidney disease, and neuropathy.
HERE are my favorite snack recommendations, all of which promote blood sugar balance.
Stress, Cortisol, and Adrenal Fatigue
Stress, or a stressor, is anything that disrupts biological homeostasis. Stress can by physical or psychological, acute or chronic, and the product of internal or external stimulation. Exercise, sleep deprivation, and poor diet are a few examples of physical stressors while work deadlines, poor relationships, and traumatic events are a few common psychological stressors. The human body manages stress, also known as a stress response, through sympathetic nervous system activation – the rapid mobilization of energy, heightened cognitive and sensory skills, and a reduction in parasympathetic nervous system function – that is also known as the “fight-or-flight” response. Within the context of human evolution, the “fight-or-flight” response has been a positive adaptation in that it helped our ancestors evade physical threats presented by hungry predators and a hostile environment. However, in the context of our relatively safe, sedentary and pre-fabricated lifestyles, the “fight-or-flight” response activated primarily by psychological stressors can unleash a physiological cascade of events that can be of tremendous detriment to our health and happiness.
Cortisol, often referred to as the “stress hormone”, is produced by the adrenal gland in response to stress to stimulate the release of stored energy from the liver, fat cells and muscle tissues, which, historically, helped us outthink or evade hazardous environments or animals. However, the abundance of psychological stressors characteristic of our modern culture from which few of us are able to efficiently and effectively escape may manifest as tissue breakdown, reactive blood sugar, and the erosion of vital organs to increase the risk of weight gain, immunosuppression, depression, anxiety, lack of energy, and an inability to concentrate.
If stress is allowed to persist, adrenal fatigue may develop, which may interfere with the production of vital adrenocortical hormones producing a laundry list of unsavory symptoms, including: difficulty getting up in the morning, continuing fatigue not relieved by sleep, craving for salt or salty foods, lethargy, increased effort to do everyday tasks, decreased libido, mild depression, less enjoyment or happiness in life, increased premenstrual symptoms, impaired memory, and decreased productivity.
Leptin and Leptin Resistance
Leptin, an anorexigenic (appetite suppressing) hormone produced in our adipose tissue, is a mediator of long-term energy balance, weight, and, by extension, disease. After we eat, leptin is released by our fat cells and travels through the blood stream and into the brain, where it influences the activity of various hypothalamic neurons and neuropeptides that work in concert to manage appetite and energy intake. As energy intake increases, fat cells grow and multiply, releasing more leptin into the blood and signaling the brain that the body’s energy needs have been met. Without human interference, energy intake matches expenditure, or homeostasis, and we maintain a healthy weight to better support our biology and activity.
Homeostasis is lost and obesity develops when hyper-palatable, nutrient deficient foods are regularly consumed or detrimental eating behaviors persist for long periods of time, both of which stimulate the overproduction of leptin and contribute to hypothalamic overexposure and the development of leptin resistance. Hyper-palatable, nutrient deficient foods are highly processed and laden with fat, sugar, and chemical additives, all of which stimulate reward pathways in the brain and motivate “seeking” behavior. Detrimental eating behaviors include periods of overeating and binge behavior, which disrupt the endocrine system and promote the overproduction of leptin.
Leptin deficiency is a condition in which fat cells do not produce an adequate amount of leptin, which can also contribute to the development of obesity and disease. However, this is a rare condition and most with leptin associated weight disorder are leptin resistant not deficient.
Ghrelin, Leptin’s Counterpart
Ghrelin, an orexigenic (appetite inducing) hormone secreted by the stomach, is fast-acting in its effect upon energy intake and homeostasis. Opposing leptin, ghrelin levels increase as the stomach empties to stimulate the hypothalamic release of neuropeptides that promote hunger and meal initiation. Ghrelin has also been found to promote greater metabolic efficiency and energy conservation so that the body’s metabolic rate drops as levels rise. As energy is brought into the system, the stomach fills and expands, ghrelin levels decrease, leptin’s effect upon appetite takes control, consumption decreases, and the body’s natural homeostatic mechanisms promote a healthy and stable weight.
Unfortunately, weight gain and obesity have been found to produce oversensitivity to ghrelin whereby marginal increases in ghrelin levels result in disproportionately greater expression of hunger. Further, ghrelin levels are inversely correlated with fluctuations in weight, which, as we previously mentioned, promotes weight stabilization. For the obese individual who is dieting, ghrelin levels increase to resist further weight loss and motivate weight gain.
Obviously, the body is a very complicated mechanism where health is “managed” by millions of infinitely finite processes taking place all at the same time. And, although it may be overwhelming to truly comprehend how these hormones function, all we really need to understand in order to help optimize endocrine function is that…FOOD MATTERS. More simply, avoid highly refined, chemical laden foods that dysregulate the endocrine system and embrace healthy amounts of fats, proteins, and vegetables to promote hormone balance.
Patience and perseverance are key when attempting to correct the hormone imbalance. There is no magic pill, food, or exercise that will allow you to skate through life eating cheeseburgers and KitKat’s. Stick with it, friends, and the results will speak for themselves.
Knowledge is power!