Protein and its role in appetite
Protein is often touted as the macronutrient of choice when trying to lose weight or control appetite, and for good reason. Protein plays a vital role in maintaining our muscle mass during weight loss. This is important but one of the other major factors is its ability to control our appetite.
You may have already heard that this was the case, but have you ever wondered why?
There are 3 major reasons why protein helps control our appetite, these are: increased satiety, ghrelin suppression, and slowing of digestion.
You may have noticed that when you eat a meal high in carbohydrates or fat and low in protein you are able to eat much more than if you had a larger serving of protein.
This is because protein keeps us feeling full and satisfied for longer periods of time. When we consume foods, our stomach releases satiety hormones called peptide YY (PYY) and cholecystokinin (CKK). These are responsible for communicating with the brain that we are full and can curb our need to eat when released in higher amounts.
Protein rich foods release greater amounts of PYY and CKK compared to other macronutrients. Because of this, we are able to stay fuller for longer.
This is great when having main meals, but an often overlooked part is the role it plays in snacks during the day. Having a protein rich snack in the morning or afternoon is going to help you tick over to your next meal and avoid unnecessary hunger pangs.
Our body’s main way to control hunger is through two hormones: Ghrelin and Leptin.
Ghrelin, often referred to as the ‘hunger hormone’ is produced in the stomach and signals to the brain that it is time to eat. When our stomach is empty, ghrelin levels will increase. When your stomach is full, ghrelin levels will decrease.
Leptin can be seen as the opposite of Ghrelin and can be seen as the ‘satiety hormone’. Leptin is produced by fat cells and is responsible for informing the brain that we do not need more food. If we have enough energy stores in the body or have recently been increasing our energy intake, leptin will increase and signal to us to eat less in order to rebalance our energy levels. As we consume more food, leptin levels will also increase.
Protein seems to have a greater effect on Ghrelin suppression compared to other macronutrients. Because of this, having protein will keep ghrelin low and therefore help control our appetite.
Protein takes a lot of energy to digest and process. Because of this, it is a long process compared to other macronutrients.
If we consider what we have just learnt about Ghrelin, it becomes clear that proteins ability to take longer to digest means that Ghrelin levels will stay lower for longer. This is because our stomach will have food in it for longer, which therefore suppresses the release of Ghrelin.
If we avoided protein and had a high GI carb instead that was the same amount of energy, we would not be full for as long since the food would be digested quickly and the lack of food in stomach would lead to increased Ghrelin production.