Role of insulin in weight gain?

Insulin plays a significant role in weight gain through its effect on hunger and fat storage. As discussed by Andrew Huberman and Robert Lustig on the Huberman Lab, insulin is released in response to sugar intake, but also in response to non-caloric sweeteners like those found in diet sodas.

When sweeteners touch the tongue, they signal the brain, which then signals the pancreas to release insulin, even if actual sugar isn't present. This insulin release can drive energy into fat stores and increase hunger, leading to weight gain. Additionally, combining diet sodas with food can condition the body to create a stronger insulin response to the diet soda alone in the future, further compounding the issue 1.

In essence, insulin's role in weight gain is twofold: increasing fat storage and stimulating hunger, both of which can lead to increased body weight.