Obesity: hormones and weight gain

Obesity is an incredibly complex disorder, however, it is well established that hormones have a lot to do with it.

Hormones are chemical messengers that regulate various processes in our bodies and, over the last decade, scientists have made truly amazing discoveries related to fat.

Fat is now actually recognised as endocrine tissue that constantly sends and receives hormonal signals to regulate body weight, control inflammation, manage the appetite, direct blood clotting and determine how our cells respond to insulin.

With all hormonal signals being sent and received from our fat, our fat actually controls how much fat we store, leading to obesity. As a result, we need to take charge of our fat cells to successfully initiate our fat loss.

Among these hormones is leptin, which controls appetite, adiponectin, which makes the body more sensitive to insulin and controls blood sugar levels, estrogen that can cause more fat gain and resistin that increases insulin resistance and, as a consequence, we put on weight.


(hormone that controls appetite)
Leptin is a key player. One’s appetite is controlled by this hormone. Leptin sends a message to the brain that we have enough energy stored (after eating) and that we don’t need to eat anymore.

Obese people have a lot of body fat and proportionally a lot of leptin in their bloodstream, so why are they unable to control their appetite? The problem occurs because leptin isn’t getting to the brain and subsequently the brain doesn’t receive the message sent by leptin that there is enough fat stored and therefore thinks that the body is starving. This is known as leptin resistance and is believed to be the main cause for obesity.

When people are leptin resistant, the hormones cause an increase in the quantity of food intake. People that are resistant to leptin overeat as the brain “doesn’t see” the leptin and thinks they are starving. It is a vicious cycle that leads to weight gain and obesity.


(also present in males)
Another hormone responsible is estrogen – sexual hormone.

Fat tissue is a huge source of estrogen production, in both men and women as it contains the aromatase enzyme, which converts testosterone to estrogen (men accumulate around the waist area). The link between estrogen dominance and obesity is undeniable.


(fat-burning hormone)
Researchers have found that this hormone increases fat burning and aids our insulin sensitivity. This hormone can be one’s secret weight-loss weapon. It boosts the metabolism, enhances the ability of the muscles in using carbohydrates for energy and increases the rate in which the body breaks down fat.

Like leptin, adinopectin is definitely a fat-loss helper.

Adinopectin and leptin work in opposition to resistin, which is a hormone that contributes to fat gain by directly causing insulin resistance in the liver and cells of the muscles. While adinopectin leads to fat burning, resistin actually fuels more fat from fat.

When it comes to weight loss, willpower on its own will not solve the problem. The body sets up a hormonal cascade which stimulates the accumulation of fat in people that are overweight and obese.

Since fat cells create more fat cells, modulating the size of the body’s fat deposits thereby contributing to the “ignition” that influences the distribution of body fat is of major importance.

Hormones are powerful chemical messengers. They control everything from the reproductive system, mood alterations and sleep, including one’s ability to lose weight.

If you are struggling to lose weight, you need to seek help by consulting a specialist in endocrinology as well as a functional dietitian.

In order to successfully lose weight, you must remember the first rule: put out the “fire” that “ignites” your hormones – and lose weight!

By Ana Rita Horta
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Ana Rita Horta is a Dietitian at the Hospital Particular do Algarve