One of the most powerful motivators we have is hunger. Seeking food when we are hungry is what allowed our ancestors to survive. For most of human history, finding the next meal could be arduous or even dangerous, so a strong physiological drive was necessary to make it happen. Now, though, the problem isn’t usually finding food, it’s having access to too much food. Unfortunately, the regulation of hunger in our brains hasn’t changed.
The physiology behind why and when we eat is the topic of my Health & Fitness column in the Aiken Standard this week.
Hunger is an internal physiological drive to seek and eat food and is usually experienced as a negative sensation. When you are hungry you may be distracted when your stomach growls. Since most of us have a supply of food that is readily accessible, severe hunger is uncommon. But when people diet to lose weight, especially a restrictive diet, hunger can be a powerful signal to eat.
Often when we think we are hungry, it isn’t hunger at all—it’s our appetite. Appetite is a psychological, as opposed to physiological, sensation that drives us to eat. Hunger and appetite can work together, but not always. The sight or smell of food can trigger can increase our appetite even if we aren’t hungry. Appetite tends to be more specific, too. While hunger will drive you to eat pretty much any food, appetite usually pushes you to eat a certain food.
One of the reasons we overeat is because we confuse appetite with hunger. We may think we need to eat when we see a food advertisement on television or smell someone cooking, but we really don’t have a physiological need for nourishment. Think about eating dessert after dinner. You just ate a full meal, so you can’t possibly be hungry. But when you see the dessert tray you develop an appetite for something sweet, even though you don’t need it.
Satiation and satiety are two other factors that influence what you eat. Satiation is the feeling of satisfaction or fullness that signals the end of a meal. Satiety is the effect of one meal, including the amount and type of food you eat, on how much you eat later. You can use these biological factors to your advantage to help you eat less.
For example, if you eat quickly you will eat more food (and calories) before satiation occurs. If you eat more slowly, you may actually eat less before that same feeling of fullness occurs. Additionally, what you eat for breakfast will impact when you feel ready for lunch and how much you eat when you do. It turns out that protein has a greater effect on satiety that either carbohydrates or fat. If your breakfast is juice and a donut you are likely to feel hungry sooner compared to having something with protein, like yogurt or eggs.
Genetics also play an important role in what we eat. Research suggests that how much we eat and even our food preferences are controlled, at least to some extent, by genes. Of course, some of this has to do with learned behavior, too. Maybe you prefer certain foods because you have a strong positive association with them developed throughout childhood.
One important point to remember is that no matter how strong the effect of genetics on food preferences, eating is a behavior that you can control. Your genes give you a predisposition, not a predetermination, meaning that even though you can’t change your genes, you can make an extra effort to not let them define you.