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Leptin and insulin resistance

Leptin and insulin resistance hormone is also known as the “obesity hormone” or “fat hormone” is directly produced by the fat cells of the body. The levels of circulating leptin promptly increase in response to an increase in calorie intake. However, leptin is insufficient for preventing weight gain and restraining feeding behavior.

Likewise, in addition to leptin’s role in obesity, it has also been associated with type 2 diabetes mellitus1. What’s more, obesity is a major risk factor for the development of leptin and insulin resistance, leading to a spectrum of metabolic alterations.

Relationship between serum leptin and insulin resistance

A study led by Gerald I. Shulma, professor of physiological chemistry, cellular and molecular physiology and medicine at Yale University found that when there is a drop in the levels of leptin and insulin, the body moves from using glucose to burning fat for fulfilling the energy requirements of the body. The research builds a basis of understanding of how to lose weight if you have diabetes.

Earlier it was known that mammals can switch from burning carbohydrates, such as glucose to instead burning fat. This allows for mammals to get energy without the process of breaking down muscle mass. Therefore, it was assumed that a decrease in the levels of insulin is what is needed to help burn fat.

However, new studies have found that a decrease in the levels of leptin is also needed. Insulin and leptin are both hormones. While leptin is responsible for curbing appetite, insulin works to decrease the levels of blood sugar by moving glucose out of the body and into the neighboring cells where it is directed stored as fat in the body or used as fuel.

Leptin and insulin resistance and weight loss

If the level of insulin is high, it also prevents fat from being broken down for energy. Whereas, leptin is linked with appetite and plays an important role in the regulation of energy. In the study, researchers studied the rate of fat and carbohydrate metabolism in a fed and fasted state.

It was observed that as the rats fasted, the levels of leptin decreased, activating a pathway that led to fat burning instead of carbohydrate burning. As a result, the rats use of stored glucose and sugar levels decreased during fasting. The bodies of the rats then broke down the body fat for it to be converted to ketones for energy2.

The study further concluded that while the levels of insulin needed to decrease for the process of fat burning to start, a decrease in the levels of leptin was also needed for the fat burning process. The findings helped researchers understand how different changes in lifestyle have an impact on the success in weight loss.

Leptin and insulin resistance
Leptin and insulin resistance


References
Wang, T. N., Chang, W. T., Chiu, Y. W., Lee, C. Y., Lin, K. D., Cheng, Y. Y., … & Huang, M. C. (2013). Relationships between changes in leptin and insulin resistance levels in obese individuals following weight loss. The Kaohsiung journal of medical sciences, 29(8), 436-443.
Perry, R. J., & Shulman, G. I. (2018). The role of leptin in maintaining plasma glucose during starvation. Postdoc journal: a journal of postdoctoral research and postdoctoral affairs, 6(3), 3.