Obesity Resource Center

Obesity Causes



What is it? Leptin is a hormone produced by the body’s fat cells (or adipose tissue) and is responsible for maintaining energy balance.

Where is it produced? Fat cells produce leptin which is then secreted into the bloodstream, signaling to the hypothalamus to eat more or less.

How is it regulated? Since leptin communicates to the brain that enough fat is stored, energy is regulated by the hormone including calories expended and consumed. Without leptin, humans may be prone to overeating or starvation.

Symptoms of Leptin resistance: Weight gain is the main symptom of leptin resistance, followed by incessant food cravings, fatigue, and histamine intolerance.

How does it impact obesity? Since the amount of leptin is proportional to the amount of fat in the body, leptin resistance can drive obesity by not indicating to the brain that enough food has been consumed. Having more fat cells can create more leptin, however this does not necessarily result in greater eating control. Leptin signaling to the brain may not be working properly, causing you to eat more and store more fat.

Correcting imbalance – A diet low in sugar can increase leptin sensitivity along with the addition of probiotics and high fiber foods.



What is it? Insulin is a hormone that regulates blood glucose, preventing levels from getting too high or low. Decreased insulin production deregulates this process causing diabetic conditions.[1]

Where is it produced? Insulin is produced by the pancreas, allowing the body to use glucose from the sugars and carbohydrates consumed, storing this glucose as energy for later use.

How is it regulated? Insulin is regulated by the pancreas. Sugar, which is needed for fuel cannot be stored into your cells directly, therefore the pancreas releases insulin into the bloodstream so that your body’s cells may properly absorb sugar and infuse this energy into your muscles, liver, and fat cells.

Symptoms of Insulin Resistance: Insulin resistance occurs when your body’s organs do not properly respond to insulin by not absorbing glucose from the blood. At this point, the pancreas either produces too much insulin, or not enough. This can result in chronic high blood sugar levels which can lead to health complications such as diabetes and heart disease. High blood sugar (hyperglycemia) symptoms include persistent thirst, headaches, blurred vision, frequent urination, weakness, dizziness, fatigue, weight loss, high blood sugar readings.[2]

How does it impact obesity? Obese patients, due to diet, lifestyle and genetic factors are likely to have developed type 2 diabetes as a cause or effect of their condition.[3]With type 2 diabetes, the body either doesn’t produce enough insulin or is resistant to insulin production. If the body does not respond properly to insulin, the liver can produce an excessive amount of glucose. This contributes to high blood sugar levels and excess fat storage. Therefore, insulin resistance and type 2 diabetes have a strong causal relationship to obesity.[4]

Testing – Blood tests are used to diagnose diabetic conditions, however testing for insulin resistance specifically is rare and complex. Since insulin resistance is linked to prediabetes, however, the following tests can give you insight on your susceptibility to insulin resistance:

A1C—5.7 to 6.4 percent

FPG—100 to 125 mg/dL (milligrams per deciliter)

OGTT—140 to 199 mg/dL[5]

Overweight or obese patients should be tested for pre-diabetes since their risk factor is high.

Correcting Imbalances – Increasing your physical activity level, and losing weight are primary steps towards regulating your insulin levels. While lowering sugar and carb intake is a great idea for those with high blood sugar, those who have been diagnosed with a diabetic condition should consult with a doctor before embarking on any new diet strategies to avoid too low blood sugar levels which can potentially become life-threatening.[6]



What is it? CCK or Cholecystokinin is a hormone that is released after a meal to aid in digestion and reduce appetite. CCK stimulates the production of bile in the liver in order to reduce the size of fat droplets thus, easing digestion. CCK also increases fluid production and enzymes from the pancreas so that fats, proteins and carbohydrates are sufficiently broken down.

Where is it produced? CCK is produced by cells in the stomach lining as well as by neurons in the brain.

How is it regulated? Proteins and fats in the stomach stimulate the release of CCK in the bloodstream which occurs approximately 15 minutes after eating, and lasts for up to three hours.

Symptoms of CCK imbalance: Persistent hunger during and after meals may be a sign of low CCK.

How does it impact obesity? Low levels of CCK has been found in obese patients, which may contribute to a decreased ability to feel full and satisfied along with much difficulty losing weight. Genetic variations might be responsible for one’s lack of CCK, rather than diet or lifestyle.[7]
Testing – A genetic variant called cholecystokinin H3 which is associated with a 60% increased risk of obesity can be tested using a cholecystokinin assessment.

Correcting imbalance – High levels of CCK have not been shown to have any effects, while too little CCK can lead to increased appetite.[8] Researchers suggest consulting your doctor for testing and individualized approaches to hormone rebalancing.



What is it? Ghrelin is considered a hunger hormone that stimulates appetite, increased food intake, and promotes the storing of fat. Moreover, ghrelin stimulates the release of growth hormones and breaks down fat tissue.

Where is it produced? Ghrelin is primarily produced by the stomach but also the intestine, pancreas, and the hypothalamus.

How is it regulated? Food intake regulates ghrelin, which causes its blood levels to rise prior to eating. Associated with hunger pangs, ghrelin is responsible for that nudge we get to eat, particularly while fasting or in-between meals.

Symptoms of Ghrelin imbalance: Ghrelin tends to increase while dieting and fasting since its mechanism is to prompt eating.

How does it impact obesity? Interestingly, obese patients tend to have lower levels of ghrelin than lean people. However, obese patients may be more sensitive to ghrelin as a whole, causing them to consume more.[9] Additional research is needed in this area.

Correcting imbalance – Ghrelin can most easily be impacted by diet. A high protein, high-fiber diet can help to prevent persistent hunger pangs.



What is it? Cortisol, often referred to as the stress hormone, regulates various processes within the body including metabolism, memory formation, inflammation, blood pressure and immune responsiveness.

Where is it produced? Cortisol is produced in the cortex of the adrenal glands where it is released into the bloodstream. Nearly all cells contain cortisol receptors which function in different ways.

How is it regulated? Cortisol is regulated by the hypothalamus, pituitary glands, and adrenal glands. Cortisol levels change throughout the day and can fluctuate based upon a person’s sleep schedule.

Symptoms of Cortisol imbalance: High cortisol levels which are mainly induced by stress, can cause a variety of symptoms such as high blood pressure, rapid weight gain, osteoporosis, mood swings, low libido, anxiety, depression, and chronic fatigue. While low cortisol may produce dizziness, muscle weakness, mood changes, and can potentially become life-threatening.[10]

How does it impact obesity? Both low and high cortisol levels have been linked to obesity. On the high side, consistently high levels of stress produce excess cortisol and are linked to stress eating. This combination adds to a person’s visceral fat. Studies show that those with chronic high cortisol levels have a higher body mass and larger waists than those with low levels.[11]

Testing – Cortisol levels can be measured using hair samples.

Correcting imbalance – Mitigating stress and managing emotions can decrease the amount of cortisol and adrenaline released into the bloodstream. Adhering to a healthy diet with plenty of magnesium, exercise, restful sleep, and relaxation practices can help return cortisol levels back to normal.


Progesterone & Estrogen

What is it? Progesterone is a hormone released during the second half of a woman’s menstrual cycle and also aids in sustaining fetal development in early pregnancy. Estrogen promotes the growth of the physical features and cycles that support reproduction and pregnancy.

Where is it produced? Progesterone is released by the corpus luteum in the ovary in order to prepare the body for pregnancy. Estrogen is produced in the ovaries and adrenal glands.[12]

How is it regulated? The corpus luteum produces progesterone approximately 14 days into the menstrual cycle. If pregnancy occurs, progesterone levels rise in order to establish the placenta, support lactation, and strengthen the pelvic wall. If pregnancy does not occur, progesterone production ends its cycle.[13]

Symptoms of Estrogen & Progesterone imbalance: Changes in these hormone levels occur frequently due to the stage of a woman’s menstrual cycle, diet, environment, lifestyle, and age. Low progesterone levels or estrogen dominance can result in weight gain, miscarriages, uterine fibroids, and ovarian cysts.[14]

How does it impact obesity? Low progesterone causes estrogen dominance, which can turn more calories into fat. Body fat also causes higher levels of estrogen, as the two go hand in hand. Long periods of low progesterone can inhibit weight loss and contribute to obesity if not corrected.

Testing – Lab testing for estrogen levels can be administered by a gynecologist via blood, urine, or saliva testing.

Correcting imbalance – Progesterone cream or hormone therapy is available for restoring balance, as well as stimulating weight loss. Those with elevated body fat tend to have more estrogen than progesterone so maintaining a healthy weight to balance hormones is key. Also, be sure to consume organic meat without added hormones and incorporate more cruciferous vegetables that contain hormone balancing compounds.[15]



What is it? Testosterone is the hormone that causes the development of male features and characteristics including reproductive organs, sperm creation, libido, and specific changes during puberty. Women do carry low levels of testosterone in the bloodstream however, males tend to carry much higher levels.

Where is it produced? Testosterone is produced by the testicles or gonads, as well as by the adrenal glands.

How is it regulated? The hypothalamus and pituitary gland control the amount of testosterone produced by the testicles. Testosterone levels are traditionally higher in the morning and resort back to normal levels throughout the day.

Symptoms of Testosterone imbalance: Higher levels of testosterone may have a bigger effect on the body based on age. Pubescents with too much testosterone may exhibit early puberty, while adult males may show no symptoms. Low testosterone is considered a more damaging issue, as fertility, a loss of muscle mass, erectile dysfunction, osteoporosis, and other symptoms may arise. Sex hormone levels like testosterone and estrogen do tend to decline naturally as we age.[16]

How does it impact obesity? Obesity and low testosterone do have a cause and effect relationship, since low testosterone can interfere with muscle growth thus, impairing the ability to properly burn fat. Additionally, fat cells metabolize testosterone to estrogen which lessens the amount of available testosterone. A male with excess body fat may also be contributing to low levels of testosterone.[17]

Testing – Blood tests are available to detect low testosterone (low T) levels.

Correcting imbalance – Returning to a healthy weight which can include cardio exercise, weight training, and a proper diet (estrogen free) can improve male testosterone levels.



What is it? DHEA (dehydroepiandrosterone) is a hormone that aids in the production of sex hormones, namely testosterone and estrogen.

Where is it produced? DHEA is produced by the adrenal gland and is circulated throughout the body.[18]

Symptoms of DHEA imbalance: Since DHEA levels decline later in adulthood, a DHEA imbalance may be responsible for many age-related issues in men and women such as mood changes, sleep disturbances, poor sexual function, aging skin, and osteoporosis.[19]

How does it impact obesity? Low DHEA might impact how well the body metabolizes fat. DHEA supplements have been used for weight loss due to the hormone’s impact on fat metabolism. Studies show that DHEA reduces fat accumulation in both genetic and diet-related obesity cases by activating a receptor (PPAR-alpha receptor) that helps the body metabolize fat more efficiently.[20]

Testing – A DHEA-S test can be administered to check levels of the hormone and whether your adrenal glands are fully functioning.

Correcting imbalance – DHEA supplements are widely available for purchase but seeking advice from a medical professional first is recommended.




What is it? Melatonin is a hormone that induces sleep and can also help regulate sleep patterns (circadian rhythms).[21]

Where is it produced? Melatonin is a hormone and neurotransmitter secreted by the pineal gland and is directly affected by light exposure to the eyes. Melatonin levels peak at night, while remaining relatively low during the day.[22]

How is it regulated? Pineal melatonin production is regulated by an area of the brain called the suprachiasmatic nuclei which halts melatonin production during the day, becoming less active at night so melatonin can be secreted for sleep. Darkness is a key factor in regulating melatonin and exposure to light can greatly reduce its production.[23]

Symptoms of Melatonin imbalance: Melatonin deficiency is linked to sleep disorders such as insomnia and sleepwalking, though a variety of contributing hormonal factors might be just as responsible. Irregularities in sleep schedules, exposure to light, and consumption of caffeine or alcohol can impact melatonin levels.[24]

How does it impact obesity? Several studies have linked melatonin to the burning of calories and curbing of weight gain.[25] Given that decreased sleep duration and poor sleep habits have been associated with metabolic disorders and an increased risk of obesity, melatonin may improve sleep quality, thus lowering these risks.[26]

Testing – Melatonin testing can be performed by a non-invasion saliva test.

Correcting imbalance – Though melatonin is available over the counter at many pharmacies, research has yet to determine the effects of chronic melatonin supplementation. Melatonin supplements haven’t been formally lined to any adverse side effects however, the best approach is to stimulate your body’s natural production of melatonin by dramatically reducing your exposure to light 30-60 minutes before you go to sleep (this includes turning off cellphones, televisions, and computer screens).



What is it? Often referred to as the ‘feel good’ or ‘reward’ neurotransmitter that signals pleasure to the brain. It also regulates certain body movements, memory, emotions, attention, and other aspects of mental processing.[27]

Where is it produced? Dopamine is released by neurons or brain cells.[28]

How is it regulated? Dopamine is regulated by the central nervous system however, levels of dopamine can be directly impacted by our lifestyle and habits. Dopamine plays a large role in addictive behaviors such as overeating or the use of drugs or alcohol which can disrupt proper signaling to the brain.[29]

Symptoms of Dopamine imbalance: Dopamine deficiency is linked to various mental disorders such as depression, anxiety, and even schizophrenia. There are also several physical symptoms related to a deficiency which include muscle pain, dizziness, constipation, weight gain, lack of energy, poor concentration, and fatigue. Substance abuse can deplete a person’s dopamine levels and further heighten the risks for mental disorders.[30]

How does it impact obesity? Dopamine deficiency has been linked to obesity and weight gain, primarily due to its impact on the brain’s reward circuit. Food addiction (as well as other addictions) causes an increase in dopamine levels which leads to the reinforcement of these behaviors. Being driven by temporary pleasure, overeating is shown to be directly affected by dopamine reward levels.[31]

Correcting imbalance – Correcting a dopamine imbalance is largely based on lifestyle. Improving one’s diet, reducing stress, stopping addictive behaviors, and increasing physical activity can drastically normalize dopamine levels. Dopamine supplementation is also available but be sure to consult with a medical professional first.[32]



What is it? Serotonin is the key hormone responsible for stabilizing mood and emotional wellbeing.

Where is it produced? Serotonin is produced in the brain and communicates with the central nervous system, aiding in the regulation of sleep, libido, eating, and digestion.

Symptoms of Serotonin imbalance: Both low and high levels of serotonin are linked to various emotional disorders such as depression and suicidal tendencies, anxiety, and obsessive compulsive disorder. Serotonin syndrome, is a condition where high levels of serotonin are produced (typically due to certain medications). Sweating, headaches, hypertension, irregular heartbeat and GI symptoms are a few of its effects.[33]

How does it impact obesity? Studies suggest that serotonin may play a role in eating behaviors, with food intake increasing when serotonin levels are low.[34] Given that serotonin directly impacts mood, overeating might be considered a need to create ‘reward’ feelings, in order to compensate for low serotonin.

Correcting imbalance – Serotonin imbalance can be corrected with a healthy diet including amino acids and a balanced nutritional profile. Serotonin supplements are also available but anyone considering taking them should consult with a medical professional, as too much serotonin can cause health problems.

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[1] https://www.endocrineweb.com/conditions/type-1-diabetes/what-insulin
[2] https://www.webmd.com/diabetes/guide/diabetes-hyperglycemia
[3] https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
[4] https://www.diabetes.co.uk/news/2018/jan/genetic-study-shows-evidence-that-insulin-causes-obesity-90446176.html
[5] https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
[6] https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
[7] http://www.yourhormones.info/hormones/cholecystokinin/
[8] https://www.hormone.org/hormones-and-health/hormones/cholecystokinin
[9] http://www.yourhormones.info/hormones/ghrelin/
[10] http://www.yourhormones.info/hormones/cortisol/
[11] https://www.medicalnewstoday.com/articles/316074.php
[12] https://www.livescience.com/38324-what-is-estrogen.html
[13] https://www.hormone.org/hormones-and-health/hormones/estrogen
[14] http://www.yourhormones.info/hormones/progesterone/
[15] https://www.healthcentral.com/article/progesterone-helps-weight-loss
[16] http://www.yourhormones.info/hormones/testosterone/
[17] https://www.webmd.com/men/what-low-testosterone-can-mean-your-health#1-4
[18] https://www.uofmhealth.org/health-library/hn-2837008
[19] https://www.mayoclinic.org/drugs-supplements-dhea/art-20364199
[20] https://www.health.harvard.edu/newsletter_article/DHEA_makes_the_fat_go_away
[21] https://nccih.nih.gov/health/melatonin
[22] http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/pineal.html
[23] http://www.yourhormones.info/hormones/melatonin/
[24] https://instituteofhealthsciences.com/maximising-your-melatonin/
[25] https://medicalxpress.com/news/2018-05-melatonin-calories-curbs-weight-gain.html
[26] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3632337/
[27] https://www.healthline.com/nutrition/how-to-increase-dopamine
[28] https://universityhealthnews.com/daily/depression/what-is-dopamine-understanding-the-feel-good-hormone/
[29] https://www.drugabuse.gov/publications/drugs-brains-behavior-science-addiction/drugs-brain
[30] https://www.medicalnewstoday.com/articles/320637.php
[31] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368677/
[32] https://universityhealthnews.com/daily/depression/8-natural-dopamine-boosters-to-overcome-depression/
[33] https://www.medicalnewstoday.com/kc/serotonin-facts-232248
[34] https://conscienhealth.org/2018/03/serotonin-and-obesity-not-just-in-your-head/