Which Hormone Tells Us We Are Full?

Leptin is the primary hormone that signals fullness to the brain. It's produced by fat cells and informs the hypothalamus, the brain region controlling appetite, that sufficient energy is stored. This signals a feeling of satiety, or fullness.

• Fat Storage Indicator: Leptin levels reflect the amount of body fat. Higher fat stores lead to higher leptin levels, signaling fullness.
• Hypothalamus Communication: Leptin crosses the blood-brain barrier to communicate directly with the hypothalamus.
• Appetite Regulation: This communication suppresses appetite, leading to reduced food intake.

While other hormones, such as ghrelin (which stimulates hunger) and cholecystokinin (which aids in satiety), play roles in appetite regulation, leptin is the key hormone responsible for long-term fullness signals based on energy reserves. Ghrelin's effect is more short-term, decreasing dramatically after eating. As stated in the provided reference, "[Leptin] lets your brain know when you have enough energy stored and feel “full.” Ghrelin plays a role in the short-term control of appetite while leptin controls long-term weight control."

Other Factors Affecting Fullness

It's crucial to note that feeling full is not solely determined by hormones. Other factors such as:

• Stomach distension: The physical stretching of your stomach as it fills with food.
• Nutrient absorption: The rate at which your body absorbs nutrients from the food.
• Eating speed: Eating slowly allows for better hormonal signaling.

These factors, combined with leptin levels, contribute to overall satiety.