How Hormones Affect Weight Loss

How Hormones Affect Weight Loss

Is it poor food choices and sedentary lifestyles that lead to weight gain and hormone imbalances? Or is it hormone imbalances that lead to food cravings, fatigue, and weight changes? In truth, both can be true, so it depends on the person.

Hormone imbalances and weight gain often have a chicken or the egg dynamic and at times it can be hard to know which came first. One thing is for sure, we can start right now, right where you are, and balance your hormones and achieve weight loss.

Effective weight loss is becoming a growing issue in the developed parts of the world where obesity is on the rise due to easy access to affordable and tempting foods, in combination with decreased physical activity. Yet, thanks to growing research in the field, we are now able to better understand our bodies and win the fight against the bulge. This article will focus on the effect of hormones on weight loss.

Why do hormones matter?

The potential of hormone imbalances to cause weight changes have been known for a long time. However, it was not until recently that hormones have been getting the attention they deserve.

It is not uncommon for someone to set out on a diet and exercise plan, only to be fraught with failure. Unfortunately, often times it is not until after they have failed and been told they “did not try hard enough” that hormones are finally considered. Needless to say, this approach is completely wrong. Hormones should be checked at the beginning of any weight loss program.

Since hormones are essential for the proper functioning of our body, their role should never be ignored. Hormones impact our metabolism, energy levels, the foods we crave, how much food we crave, and play a vital role in the growth and development of bones, muscles, and other tissues.

So what are hormones?

To say that hormones are the messengers of the body would be an oversimplified, but true statement. Hormones, which are chemical signaling molecules, are produced by various glands in the body which, together, form the endocrine and exocrine systems.

Hormones transfer information between organs and stimulate various actions of these organs. In this manner, hormones help the regulation of various processes that take place in the body. The examples of such processes are:

  • Metabolism
  • Digestion
  • Sleep
  • Growth
  • Respiration
  • Tissue development and function
  • Mood
  • Reproduction
  • Excretion
  • Sleep
  • Stress
  • Lactation
  • Sensory perception

Hormones can have effects on both nearby and distant cells and are able to change the function of the cell. The maintenance of hormonal balance is very important because long-term changes in hormone levels are certain to lead to health complications.

Hormones that affect weight

While other hormones can affect weight as well, there are seven hormones that are most often associated with unwanted weight gain and unsuccessful weight-loss attempts. These are ghrelin, leptin, thyroid, cortisol, insulin, estrogen, and testosterone.


Ghrelin is a hormone produced in the gastrointestinal tract. It is secreted by specific ghrelinergic cells located in the lining of the stomach. The most important role of ghrelin is to signal hunger to the brain when the stomach is empty. For this reason, ghrelin is also known as the “hunger hormone.”

Ghrelin causes the brain cells to stimulate increased production of gastric acid and amplify the feeling of hunger. Both of these actions result in an increased appetite, which often leads to overeating.

Scientists have found that lack of sleep, poor balance of gut microbes, and being overweight can cause an increase of ghrelin levels. This explains why when we get less sleep we often have more food cravings. Ghrelin levels tend to increase with age. This might explain the age-related weight gain that most people experience.

Luckily, there are ways to keep ghrelin levels under control. These include:

  • Sleeping at least 8 hours per night
  • Keeping the blood sugar levels stable with a balanced diet
  • Maintaining an active lifestyle
  • Fasting
  • Balancing gut microbes

Gastric bypass surgery and bariatric surgery are very efficient in significantly lowering ghrelin levels. However, the duration of this effect and its long term results are still not clearly known.


Leptin is another hormone with an important role in appetite control. A major task of leptin is to inhibit hunger by delivering information to the brain that there is adequate intake of food (fullness). It is quite normal to think that higher levels of this hormone would result in an appetite decrease, however, this is not the case.

Leptin is produced by the adipose cells also known as fat cells. The greater the quantity of stored fat the bigger the production of leptin is. High levels of leptin result in leptin resistance or a decreased sensitivity to this hormone. Based on all this, we can see that obesity causes high leptin levels and consequently an increased appetite.

Many obese people report that they have difficulties detecting satiety which allows them to over-eat easily. There are blood tests available that can help to diagnose leptin resistance and once diagnosed, this condition can be treated. The treatment involves dieting and exercise with the purpose of melting down the excess stored fat. As the fat deposits decrease, the production of leptin decreases as well and this hormone again takes up its role in regulating energy balance and appetite.


Cortisol, which is produced in the adrenal gland, is known as the fight or flight hormone because it is released in response to stress. In addition to stressful situations cortisol is also released based on our sleep-wake cycle. In the average person, cortisol is released 5-7 am, letting our body know its time to wake up, then starts to lower midday, which is often why people have a slump around 3pm, then it fully bottoms out by night letting the body know its time for bed. In terms of diet, cortisol is released when we are running low on glucose supplies in the body.

The instant rise of cortisol levels due to stress can be felt like a sudden and short-term energy boost. Some common situations in which increased amounts of cortisol is released includes:

  • During a fight
  • While exercising
  • In life-threatening circumstances
  • When chasing deadlines at work
  • When the body is low on glucose

When cortisol levels are high people will experience a suppression of other processes such as sexual desire, hunger, digestion, and immune response.

This is done to help the body focus better on the leading cause of stress. However, these cortisol spikes are only useful if they happen less frequently and last for a short period of time. When people are living in chronic states of stress, such as having high demands from a work project, their cortisol levels will remain elevated and lead to a whole slew of issues from weight gain to fatigue.

Certain types of diet such as fasting and ketogentic also affect cortisol levels. During the initial stage of food or carbs deprivation, cortisol rises and has an important role in the breakdown of glycogen stored by the liver and muscles. This speeds up the weight loss process and significantly increases the amount of lost weight during the first week or so.

Later, if the diet regimen is continued the role of cortisol changes and it helps with the creation of glucose from non-carbohydrate sources such as fat or protein (gluconeogenesis). However, if the food intake remains inadequate for a long period of time and the body enters the stage of starvation. In starvation mode cortisol will alter its function again and begin the breakdown of proteins from the muscle tissue (muscle wasting).

Higher levels of cortisol over time are related to the following issues

  • Depression
  • Weight gain
  • Sleep deprivation
  • Anxiety
  • Headaches
  • Sugar cravings
  • Digestive problems

The best way to control cortisol levels is to get rid of stress and implement relaxation with a massage, yoga, and meditation.


Insulin plays one of the largest roles in how the body uses fuel for energy, or more specifically, on cellular metabolism. 

Glucose, or sugar, is the body’s favorite source of energy and insulin is the hormone that enables sugar to enter the cells. Once sugar is inside the cells, glucose-to-energy transformation is able to occur.

Whenever we eat, the pancreas releases insulin which allows glucose to be turned into energy and used by the muscles, brain, and other tissues.

By enabling the transformation of glucose to energy, insulin helps to decrease sugar levels in the blood. This is a very positive thing. However, a long-lasting high-calorie diet rich in carbs will cause insulin levels to remain elevated over a longer period of time than is healthy. Often, this results in insulin resistance.

The decreased sensitivity to insulin (insulin resistance) inhibits the glucose-to-energy transformation and, instead of glucose being spent by the muscles, the excess glucose gets stored as fat. Insulin resistance is therefore characterized by weight gain, decreased physical activity, and food cravings. The combination of all these factors is the main cause of type II diabetes.

Low carb diets, such as ketogenic, Atkins, and fasting diets, are a good way of lowering insulin levels. Low levels of insulin have a catabolic (destructive) effect on stored fat and are highly beneficial for weight loss. These diets also reduce the risk of diabetes and help the control of symptoms in people already affected by the condition.

There are blood tests designed to determine insulin levels and help diagnose insulin resistance. Physical activity, balanced diet, medications, and weight loss can increase insulin sensitivity and help your body to manage blood sugar levels more efficiently.

Thyroid hormones

The thyroid is a gland that is located in the lower part of the neck and plays a large role in metabolism. The thyroid gland produces two hormones, T3 (triiodothyronine) and T4 (Thyroxin). Any kind of disruption in the production of thyroid hormones will have a negative health effect. Two common problems with the function of the thyroid gland are hypothyroidism and hyperthyroidism. 

  • Hypothyroidism is a condition characterized by low production of thyroid hormones
  • Hyperthyroidism is excessive production of thyroid hormones

Low levels of thyroid hormones, over a longer period of time, will slow down the metabolism and inevitably result in weight gain.

Higher than normal levels of thyroid hormone will boost metabolism and cause unexpected weight loss. While this may sound great, this elevated state will stress the body and lead to unwanted consequences like heart arrhythmias.

T3 and T4 also affect other hormones such as the TSH (Thyroid Stimulating Hormone). The role of  TSH is to stimulate the thyroid gland and dictate its work rate. The levels of TSH will rise and drop opposite of the T3 and T4 levels, bringing the thyroid gland in an imbalance. This type of seesaw effect can be a cause of many health problems.

Symptoms of hypothyroidism (underactive thyroid)

  • Weight gain
  • Depression
  • Constipation
  • Cold sensitivity
  • Muscle cramps
  • Loss of libido
  • Irregular periods (women)
  • Slower growth (children)
  • Memory issues (elderly people)

Symptoms of hyperthyroidism (overactive thyroid)

  • Mood swings
  • Heat sensitivity
  • Tiredness
  • Nervousness
  • Irritability
  • Anxiety
  • Chronic thirst
  • Muscle weakness
  • Diarrhea
  • Decreased libido
  • Weight loss

Stress is a big contributor to changes in thyroid function. Standard blood tests use TSH, T3, and T4 levels to detect any thyroid-related issues. 

Common causes of hypothyroidism

  • Autoimmune reaction known as Hashimoto’s disease
  • Previous surgical or radiation treatment
  • Lack of iodine in the diet
  • Congenital causes

Common causes of hyperthyroidism

  • Graves’ disease
  • Benign thyroid nodules
  • Increased levels of iodine in the body (usually caused by the use of medications)
  • Thyroiditis
  • Pituitary adenoma (a type of benign tumor)
  • Thyroid cancer (rare)

Symptoms of underactive thyroid are usually treated with synthetically produced thyroid hormones (e.g. levothyroxine). The correct dose of the medication is determined with a series of blood tests. An overactive thyroid, however, is treated with thyroid hormone blockers, radioactive iodine therapy, or surgery.


Estrogen is the most important female sex hormone. It performs many significant actions in the female body, such as:

  • Acceleration of metabolism
  • Formation of sex characteristics during puberty
  • Maintenance of fluid balance
  • Fat storage increase
  • Cortisol increase
  • An increase in sexual desire
  • Regulation of HDL and LDL cholesterol levels

These are only a few major estrogen functions. There are many more important processes in which estrogen has a part, however, these are less important when talking about weight loss.

The changes in estrogen levels are best observed during a woman’s menstrual cycle. Even those regular changes can cause a temporary change in body weight, mostly a consequence of water retention (bloating).

In menopause, women commonly experience a decrease of estrogen levels. Very often this decrease is followed by an increase in weight. The interesting fact is that most of the newly gained weight is usually located in the hips, thighs, and belly area.

Estrogen replacement therapy and exercise can help women to maintain, or increase, the muscle mass and boost the metabolism during menopause. Estrogen replacement therapy also works well in suppressing the episodes of uncontrollable eating (binge eating). Estrogen is able to replace certain serotonin “happiness hormone” neurons, which are responsible for the feeling of joy during binge eating.

Men also produce estrogen, from testosterone, although in lower quantities than women. The production of testosterone decreases in middle-aged men and so do the levels of estrogen. This is one of the main reasons why older men tend to accumulate fat deposits around the waistline.


Testosterone is the male sex hormone that is produced by the testicles of males. Female ovaries also produce some testosterone, but the quantity is around twenty times smaller than in males.

Testosterone is an anabolic steroid. This means it has the ability to increase the amount of protein in cells. The effect of this hormone can best be observed in the buildup of muscle mass, hence the difference between the percentage of muscle tissue in males and females.

To help the body increase muscle mass and form the male secondary sex characteristics, testosterone increases appetite. More food means more nutrients to be used as energy. However, the quality of these nutrients is also important. That is why a balanced diet will lead to lean mass gains, while bad dietary habits will cause an increase in fat deposits.

Other major processes in which testosterone has a role are:

  • Muscle and bone tissue increase
  • Body hair growth
  • Prevention of osteoporosis
  • Formation of testes and prostate

Because of this, a decrease in testosterone levels inevitably leads to a loss of muscle mass and decreased bone density. Fewer muscles mean fewer calories burned and if dietary habits do not follow these changes, weight gain is inevitable.

Stress and lack of sleep can cause a drop in testosterone levels. The use of synthetic anabolic steroids to increase athletic ability can seriously lower the production of testosterone in the body. However, the leading cause of a decrease in testosterone production is aging.

Both women and men produce less testosterone later in life. The consequences of this are better visible on men. Low testosterone levels in men are associated with:

  • Weight gain
  • Loss of muscle mass
  • Fatigue
  • Erectile dysfunction
  • Low sex drive
  • Sleeping difficulties
  • Hair loss
  • Mood swings

Testosterone Replacement Therapy (TRT) is a standard treatment for low testosterone levels. Therapy can be administered in a number of ways, including tablets, pills, injections, gels, and skin patches.

The Final Word

Hormone levels affect our health in numerous ways and when it comes to maintaining a healthy weight, their importance cannot be overlooked. If you are, despite your best efforts, struggling to lose weight you should seek professional help and check your hormonal health. It might prove to be the missing part of the puzzle.

Written By
Jessica Chrisman
Certified Family Nurse Practitioner

Jessica Graduated magna cum lade from the University of Miami with a Masters of Science and is a board certified FNP. While in school she worked at a cardiac clinic where she served as the head research liaison on a pacemaker and coronary artery study. As a medical provider Jessica has worked in a wide range of specialties including primary care, epidemiology, cardiac surgery, ENT, occupational health, and longevity. She has also held management positions as the clinical director of an epidemiology practice that focused on global health and collaborated with UCLA on their Monkey pox study. Most recently she works as a medical director at one of the top entertainment companies where she treats employees, oversees operations, and creates educational content. Jessica has a passion for education and bridging the gap between health and modern day living. She consults for several health startup companies, some of which have included WebMD and Care Message. Creating and implementing educational programs for students and employees, Jessica has guest lectured at various campuses and places of employment.

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