Obesity is one of the most serious conditions that affects children and adults all over the world. More often than not, poor dietary habits and a sedentary lifestyle are the most common contributory factors for weight gain. However, people may even be genetically predisposed to weight gain. Obesity can make one vulnerable to various serious ailments which is why one must follow a healthy diet and stay physically active to keep one's body weight under limits. However, there are times when a person may gain weight despite following a low-fat diet and exercise regimen. Well, a hormonal imbalance could be the reason behind such an unexplained weight gain. In this article, we would be looking into the connection between imbalance in the levels of hormones and weight gain. Connection Between Hormones and Weight Gain Can hormones cause weight gain? Research has established a clear link between fluctuations in the levels of certain hormones and weight gain. Hormones are the chemical messengers of our body, and are secreted by endocrine glands such as the pituitary gland, adrenal glands, thyroid gland and pancreas. The secreted hormone travels through the blood stream, and induces a special effect on the target tissue or organ. Hormones carry messages from the gland to the cells within the targeted tissues or organs and accelerate chemical reactions at the cellular level. Various vital processes are dependent on the secretion of these hormones, and their concentration. If the hormones are not secreted in the right amounts, one may become susceptible to various health problems. One may be at an increased risk of developing hypertension, diabetes, osteoporosis or infertility due to hormonal imbalance. Weight loss and weight gain could also be attributed to an imbalance in the levels of certain hormones. Here's some information on the hormones that have a direct impact on body weight. Estrogens: Estrogens are a group of steroid hormones synthesized in the ovaries in females, and in the testes in males. Although estrogens are female sex hormones, they are present in males in smaller amounts. In females they play an important role in ovulation, menstrual cycles and development of secondary sexual characters; whereas in males they are essential for sperm maturation and viability. In addition, these hormones influence lipid metabolism in both males and females. A decline in their concentration leads to an increase in the fat reserves of the body, more specifically in the abdominal region, thus resulting in weight gain. Estrogen deficiency causes metabolic dysfunction which may increase the risk of obesity. The level of estrogens decreases in post menopausal women and age-matched men, and is one of the reasons for weight gain in middle-aged people. Progesterone: Progesterone is another type of female sex hormone, and is also known as the pregnancy hormone. It is synthesized in the ovaries and by the placenta during pregnancy. It is synthesized in small amounts in males by the adrenal gland, and plays an important role in reproductive health as well as several other physiological processes. In both the sexes, progesterone influences appetite and weight gain. A decrease in serum progesterone levels leads to an increase in adiposity and thus weight gain. Such a reduction can be the result of hormonal imbalance and endocrine disorders like polycystic ovary syndrome (PCOS) in females and reduced adrenal gland function in males. Testosterone: This male sex hormone is synthesized in the testes and ovaries as well as in the adrenal cortex. It influences bone and muscle density and hence influences weight in both males and females. Muscle cells burn calories in the body and keep the rate of metabolism high. A fall in the levels of testosterone results in the loss of the body's muscle mass. This further leads to reduction of the metabolic rate, and ultimately leads to an increase in body weight. Other androgens: Apart from testosterone, other androgens like androstenedione, androstenediol and dihydrotestosterone also play a vital role in fat metabolism. They are produced by the testes in males and the ovaries and the adrenal cortex in females. These androgens inhibit lipid storage by fat cells. This function gets impaired in case of significantly low serum androgens, which may eventually lead to weight gain. In females, this specifically leads to an increase in abdominal fat. Insulin: This peptide hormone is synthesized by the pancreas, and plays the most important role in carbohydrate and fat metabolism. Disruption in this function due to reduced insulin production or due to insulin resistance leads to increased lipid stores in fat cells and weight gain. Insulin resistance may be the result of endocrine disorders like PCOS, genetic predisposition, unhealthy diet and lifestyle etc. Currently, it is one of the leading reasons for obesity. Cortisol: Cortisol is secreted by the adrenal glands in a diurnal pattern. The cortisol concentration is at its peak in the early morning and is at its lowest at night. Cortisol plays many vital roles in the body. The most important are blood pressure maintenance, fat metabolism and fast metabolism of carbohydrates to ensure energy availability to the body and stimulation of insulin release to maintain blood sugar. Under physiological-stress conditions, secretion of cortisol increases. This often alters the diurnal pattern of its production. This leads to weight gain. Excess fat accumulates around the abdomen, and is strongly correlated with cardiovascular diseases like heart attack and strokes. Because of the above explained reasons, cortisol is often referred to as the stress hormone and explicates the relation between the stress hormones and weight gain. Thyroid hormones: Another set of hormones that play a vital role in metabolism and body weight are the thyroid hormones, namely thyroid stimulating hormone, T3 (triiodothyronine) and T4 (thyroxine). Lowered thyroid function (hypothyroidism) is associated with low TSH levels and leads to decreased levels of T3 and T4. This leads to lethargy, fatigue, weakness, hypertension and weight gain. Our body needs hormones to carry out a variety of cellular and physiological processes. Any rise or decline in hormonal levels has serious repercussions on one's health. An unexplained weight gain or weight loss may be the result of a hormonal imbalance, and must be investigated by consulting an endocrinologist or an appropriate medical expert. Disclaimer: This Buzzle article is for informative purposes only, and should not be used as a substitute for professional medical advice.