Leptin, the Obesity Hormone

Leptin, the obesity hormone: Regarding weight loss and human trials, phosphatidylcholine is shown to help women loose weigh (25) with no side effects, while improving fat metabolism. It helps to lower the production of a hormone called leptin. For those of us who are aging this may be important as age usually brings about weight gain and increased adipose fat deposits (34).

Leptin effects several areas of the brain besides appetite. It can impact neuroprotection, memory, motivation, learning, and general cognitive functions, as well as growth, reproduction, metabolism, and energy expenditure (54).  If leptin production becomes disrupted, either by being overweight/obese or underweight/lacking proper nutrition, it effects how neurons function and cognition or thought processes (54).  So, bringing leptin back into balance by making the brain more sensitive to it may help improve cognitive, and other, functions.

Leptin dysregulation is associated with insulin resistance, type two diabetes, hypertension (high blood pressure), problems with blood clotting (atherothrombotic), and inflammation. It is connected with metabolic effects, oxidative stress, and shortens the life cycle of cells, called endoplasmic reticulum stress (55), increases apoptosis or cell death, and unhealthy changes in cells and body tissue (56) called remodeling (associated with type 2 diabetes).   Regarding the last, increased leptin levels may lead to inflammation in organs and tissues, and increase the likelihood of inflammatory diseases like: heart disease, rheumatoid arthritis, and inflammatory bowel disease (38).  It also contributes to injury of the liver, pancreas, blood vessels, and heart muscle (myocardium); and problems with the immune system, and blood platelets needed for clotting (38) and heart/vascular disease, diabetes, and insulin resistance (37).

Leptin is the hormone that fat cells produce to help bring on a feeling of fullness or satiety, to signal the brain that the body has the ability to produce the energy it needs (36). You would think that the more leptin produced the better, the less a person would eat.  But, the opposite is true. People who are overweight or obese tend to be leptin resistance or insensitive, which is associated with reward eating, or eating beyond caloric energy requirements.  Conversely, emotional eating may lead to leptin insensitivity as people stop recognising a feeling of fullness (35).

Leptin production goes up with body fat or adiposity. As people gain body fat, that fat produces more leptin and as more leptin is produced, the brain fails to respond to it, creating a vicious circle.  So, the reduction in leptin production indicates a renewed sensitivity to leptin, which means the individual will feel fuller sooner, and be less inclined to over eat (34).

High fructose sugar consumption is associated with leptin resistance in animal studies (34).   High fructose intake can lead to high levels of fats in the blood (triglycerides).  This is very bad, high triglycerides can lead to diabetes, heart disease, and fatty liver disease (47).  These fats in the blood seem to block the leptin in the blood from getting into the brain to signal the brain that the body should stop eating (34).  Further, high fat diets are associated with weight gain in test subjects who had high leptin levels (leptin resistance or insensitivity) but were not terrible overweight until they switched to a high fat diet (34).

Leptin insensitivity is associated with metabolic syndrome (45) and increased risk of type two diabetes, and cognitive problems (54). Leptin can modulate insulin action, or change the way it acts in the body, and can participate in the development of insulin resistance.

A bit about why this is important: insulin makes it possible for cells to absorb the blood glucose, or sugar, the body makes from food. This happens mostly in the small intestine.  Insulin helps the liver and muscles to store excess glucose, and it lowers blood glucose levels by slowing the production of glucose in the liver (48).  If a person is healthy, both insulin levels and blood glucose sit in a healthy range.  But, if the person experiences the following insulin resistance may occur: overweight or sedentary, has problems with hormones, uses steroids, is older, experiences sleep disruptions or apnea, smokes, takes certain medications or is of an ethnicity prone to this problem (48).

Insulin resistance is the inability of the body (muscle, fat, liver cells) to properly respond to insulin, making it hard for blood sugar (glucose) to be absorbed by cells. The pancreas, via beta cells, tries to produce more insulin to keep up with the greater demand.  This keeps blood sugar in normal ranges.  But, if the pancreas can’t keep up, excess blood sugar occurs and leads to the development of prediabetes, and eventually type two diabetes (48).  Prediabetes means blood glucose and the rating of it, A1C levels, are higher than normal, but not so high that diabetes will be diagnosed.   But, it is a risk factor for type two diabetes and cardio vascular disease (48).  Keep in mind that untreated insulin resistance usually results in type two diabetes within ten years.  Lifestyle changes are the best treatment.  Losing body weight, five to seven percent, exercise and dietary changes as well as smoking cessation. Type two diabetes, if untreated, results in damage to nerves and blood vessels (heart disease, stroke, kidney failure, blindness, and amputation of lower limbs).

The leptin/insulin relationship is complicated as (46) insulin stimulates the secretion of leptin in both animal and human studies.  Insulin resistance may trigger leptin resistance by disrupting the brains ability to fully be affected by leptin signals.  Eating a diet high in simple carbohydrates, sugar, and high fructose corn syrup, and not getting enough fiber and lean protein, may be part of the problem.  Sleep depravation may also play a part, as people eat more when tired or stressed (44).

Thyroid problems: are connected to elevated leptin levels. The leptin/thyroid axis has a multifaceted and twofold relationship. Leptin regulates the production of something called thyroid releasing hormone or TRH.  If there is a resistance to leptin, and your brain thinks you are not getting enough energy or calories, your brain (hypothalamus) slows production of thyroid release hormone (TRH) to force your body to slow its metabolism and store fat.  It does this as it thinks the body is starving. In reaction to this situation, the thyroid gland produces more TSH (thyroid stimulating hormone) to tell the brain to produce more active thyroid hormone.  The TSH may also be signalling the fat tissue to produce more leptin, to tell the brain that there is enough energy for it to produce more thyroid hormone (41;42). TSH is a measure of how well the thyroid is functioning.  In short, it becomes a vicious circle.  Some data indicate that treatment hypothyroidism with thyroxin lowers leptin levels, and TSH levels, in individuals with hypothyroidism (43).

The thyroid and insulin. These two things influence one another.  Poorly regulated blood sugar, called dysglycemia, lessons or slows thyroid function, but poor thyroid functioning can cause dysglycemia and insulin resistance, and even metabolic syndrome (52).

Hyperthyroidism, when it works too fast, can cause poor blood sugar control and an increase in the body’s demand for insulin. Too much thyroid hormone leads to glucose being produced by the liver, a quicker absorption of glucose, or sugar, in the intestines, and insulin resistance, or the body’s inability to use insulin efficiently (51;53).

Hypothyroidism, when the thyroid is too slow, is associated with a slower rate of glucose uptake by cells, and a slower rate of glucose absorption in the gut.   Also, there is a slower clearance of insulin from the blood, and insulin is slower to react to elevated blood sugar (52).  Hypothyroidism can result in abnormal blood lipid or fat levels. As well as having too much fat in the blood (triglyceride level) overall, there is too much total cholesterol, and too high a rating of low-density-lipoprotein (LDL) or bad cholesterol.  These factors are associated in diabetics with a higher risk of cardiovascular disease.  Hypothyroidism can slow the elimination of insulin from the bloodstream, so insulin doses may be reduced (51).

Thyroid problems and sugar. Eating sugar and simple carbohydrates (which turn to sugar in the body) drive blood sugar up too high, too fast.  The body releases insulin to try to drive it down, which can result in low blood sugar or reactive hypoglycemia (also an adrenal stressor).  This then causes anxiety, fatigue, nervousness and feelings of light-headedness (49).

When a diet is too rich in sugar or simple carbs, the pancreas produces insulin to move the extra sugar out of the blood into cells, to be used to make energy. Over time, these cells, perhaps overworked, lose the ability to deal with the insulin.  The pancreas then makes extra insulin to try to get the cells to respond.  This become insulin resistance.  Surges in insulin negatively effect the thyroid gland, destroying it, and lessoning thyroid hormone production (52).

Ironically, when a diet is too low in sugar, or the supply is inconsistent, blood sugar levels can also negatively affect the thyroid. Here, the adrenal glands produce cortisol to tell the liver to make more glucose or sugar, to bring blood sugar levels back to normal.  But if cortisol is released to often, the result is a suppression of the pituitary gland, the gland in the brain which tells your thyroid to function (52).

Fructose, from high fructose corn syrup, is a problem for the thyroid as mercury may be used in the manufacturing process. This mercury can then be found in trace amounts in the foods the fructose is used to make. The mercury may be stored for a short time in the thyroid gland.  This can damage it, mercury can break down the enzymes needed for the thyroid to properly function (496).

Regarding sugar substitutes, aspartame has phenylalanine in it. In a more natural form this is helpful to the thyroid.  It helps make thyroid hormones, but too much can disrupt tyrosine, an amino acid, from accessing the thyroid, disrupting thyroid functioning (496).

To keep blood sugar in a healthy range. Healthy blood sugar ranges are determined two ways, fasting glucose and post-prandial blood glucose.  Fasting glucose is the reading taken first thing in the morning, before eating or drinking and it should be between 75 and 95 mg/dL.  Post-prandial blood glucose is taken 1 to 2 hours after eating.  A normal reading is 120 mg/dL or lower (52).

Buy a blood glucose meter. In cases of hypoglycemia, keep blood sugar levels above 75 all day long.  Consume a diet consisting of low-to-medium amounts of carbohydrate. Eat small meals every 2-3 hours.  This will lesson fluctuations in blood sugar (52).  Alternately, if you are hyperglycemic you need to keep your blood sugar below 120 two hours after eating, so lower your intake of carbohydrates and sugar (52).

As both lecithin and choline assist in many areas of brain health, and there are several areas in the brain associated with regulating calorie intake, it may be that choline helps the brain become more leptin sensitive. This is possible in the face of the belief that even a slight injury to the leptin receptor pathway could cause obesity over time (34). Lecithin helps in cholesterol metabolism, by inhibiting its absorption and flushing it out of the system.  As lowering cholesterol is associated with lower leptin levels, this may be one of, or, the reason/s lecithin helps control and reset leptin levels.

To read about lecithin in greater detail, or access the sources for this post, go to the lecithin page.

Please not, this information is for educational purposes only.  Please contact a qualified healthcare provider if you have any health, or other, issues.

The information on this site is for educational and informational purposes only.  It is not to take the place of medical advice or treatment.   Seek out a qualified health care provider if you have questions or need help.  Dr. Grant is not responsible for any possible health consequences of anyone who follows or reads the information in this content.  Everyone, but especially those taking medication (over the counter or prescription) should talk with a physician before undertaking any changes to their lifestyle or diet (including taking supplements).