Metabolism and body weight regulation are balanced by a combination of genetics, environment and hormonal regulation. Fat cells were originally thought to be fairly neutral, but it is how known fat cells release hormones that can influence weight and health. There are many hormones that influence hunger, satiety, metabolic rate and fat storage. Researchers are still studying the full effects of their relationship with the body.
Insulin, leptin, adiponectin and cortisol are some of the hormones that influence the gain of fat mass. There are other hormones that influence weight loss and other hormones that can also influence metabolism.
Researchers are still putting the pieces together of how these, and other hormones, impact weight regulation and other markers of health.
Here is a synopsis of the roles these 4 hormones have in weight regulation and fat accumulation.
Insulin is a vital hormone; it basically brings energy into body cells they can use for energy or storage. Without insulin being released into the blood stream, body cells can starve.
If someone’s pancreas does not make insulin like in type 1 diabetes, it is imperative they take exogenous insulin because insulin is needed for cells to live.
After eating, blood sugar levels go up. This signals the pancreas to release insulin. Insulin can bring blood sugar, glucose, into body cells for energy or storage after a meal.
The higher the level of blood glucose, the higher the insulin release.
Insulin is considered an anabolic hormone; it encourages storage. Not only does it promote storage for glucose, but it also promotes fat storage which is one reason it can be considered a hormone that plays a role in obesity.
Insulin and fat mass
Insulin is secreted in direct proportion to fat mass (1). Insulin also influences how the body handles fat. Insulin is thought to interfere with lipid metabolism which could cause other negative health effects like high triglycerides, size of blood cholesterol particles and low levels of HDL cholesterol (good cholesterol).
What can happen with obesity is insulin resistance. Because insulin levels are elevated with higher fat mass levels, insulin levels in the blood can remain elevated even during fasted states.
Because insulin is constantly in the blood, the body cells can grow “deaf” to insulin.
Leptin’s role in weight regulation can be complex. Leptin is released from fat cells, and like insulin, the higher the fat mass the higher the leptin levels. Leptin is supposed to work like this.
As fat levels increase in the body, leptin sends signals to the brain that send the message to lower food intake because there is plenty of energy available in the body.
When losing fat mass, leptin levels go down which could also signal the brain to increase food intake.
Leptin stimulates fatty acid break down, glucose accumulation of cells and prevents non-fat cells from taking in fat. The fact that leptin stimulates fatty acid breakdown may sound like a good thing, but what ends up happening is the fatty acids can just hang around in the blood and other negatively interact with metabolic functions.
It is also thought that leptin can further stimulate insulin secretion and promote hyperinsulinemia (2).
As with insulin, an increased secretion of leptin can make the brain desensitized to leptin.
Therefore, while obese people can have higher leptin levels, the signal being sent to the brain to lower food intake is not being registered.
Therefore, researchers are working on how obese individuals who are leptin resistant can be sensitized to leptin’s effects.
With an increased fat mass, insulin and leptin levels are elevated. However, with adiponectin, as fat mass increases, adiponectin levels decrease. High amount of adiponectin levels are also associated with increased insulin sensitivity.
A 2004 review article suggests adiponectin may have a direct impact on insulin’s function and on lipid metabolism. Some research has shown when mice with high levels of insulin were given adiponectin, insulin levels went down (3).
Adiponectin may also be sensitive to fat mass depending on where it is in the body. For example, if more fat is accumulated in the abdominal region, adiponectin levels may be lowered more than if fat mass is gained on the lower body.
Questions how adiponectin affect the body and insulin levels are still being asked by researchers, and it may be that defects in adiponectin genes could be linked to obesity and insulin resistance.
Cortisol is one of the stress related hormones released from the adrenal glands located on top of the kidneys. Cortisol has been the focus of many weight loss supplements or weight loss programs.
Cortisol is released during periods of fasting, eating, exercising, when we first wake up and during psychological stress (4).
Cortisol has a role in energy metabolism and helps the body break down nutrients it needs for fuel.
For example, if you need to run away from a dangerous situation, cortisol can help your body use carbohydrates for quick energy. Cortisol could also move fat into storage in the abdominal area.
If cortisol levels are chronically high, it could promote fat storage in the abdomen, influence appetite as well as other metabolic processes.
Cortisol is a necessary hormone for daily life, but if levels are high it can influence fat accumulation.
Healthy stress relieving habits are recommended to counter high stress levels as well as a balanced diet and exercise.
Conclusion: Hormones that make you fat
Insulin, leptin, adiponectin and cortisol are some of the hormones that can have a direct impact on weight gain and fat mass.
If you are concerned about your hormone levels, speak with your healthcare team about your individual health.
Fortunately, even if you don’t know which hormones are or aren’t out of balance, weight loss can still be beneficial.
Implementing healthy weight loss practices can help your body lower fat mass and can also affect hormone levels.