Why fat makes us feel full

The science behind the taste of fat is quite amazing. Ready?

What does fat taste like? In the 16th century, the answer was “pinguis.” The term translates to “dense, heavy, rich.” But these are characteristics of fat, rather than the taste itself.

Recently, scientists at Purdue University coined the term “oleogustus” to reference the oily taste of fat itself. The 21st century characteristics of this term are “rancid,” “unpalatable,” and “irritable.” If this is true, why do we “all scream for ice cream?” And why do the paleo-enthusiasts swear that everything tastes better with bacon?

The answer: people confuse the un-pleasant taste of fat with the feeling in their mouth, often described as creamy, rich, or full-bodied.

Here’s the science behind the taste of fat

Fats are made of triglycerides. A triglyceride is a molecule made up of three fatty acids that can be short, medium, or long.

Triglycerides deliver fat-soluble flavour compounds (including emulsifiers, thickeners, and additives) to the brain, but your tongue doesn’t have any receptors for them. Your tongue does have receptors for fatty acids—taste buds. When you eat a fatty food, the triglycerides get broken down in your mouth and the fatty acids land on your taste buds.

To qualify as a basic taste: 

1. A flavour must have a unique chemical structure,

2. Our bodies must have specific receptors for the taste that perform a specific function, and 

3. People have to be able to distinguish it from other tastes.

Until recently, science could demonstrate only that the human palate detects five tastes: sweet, salty, bitter,  sour, and umami (savoury). Fat never qualified, because when study participants were given a variety of flavours they were unable to distinguish it.

However, when people were given only tastes that are unpleasant on their own—sour, bitter, umami—they could detect the fat. So, why does it matter if fat qualifies as a taste or not? Because you have over 100 taste receptors on your tongue. The more receptors you have for fat, the more you will feel satisfied by eating less of it.

Fat has nine calories per gram, while carbohydrates and proteins have about four calories per gram. Thus, if you have fewer receptors for fat, you will eat more calories in order to feel satisfied. On the other hand, if you have lots of fat receptors, you will feel satisfied on a lot less fat, and eat less food.

Then why do fatty foods, including avocadoes and olive oil, taste so good? The answer: fat concentrates smells and flavours in food. It emulsifies ingredients in food products to give foods a smooth creamy texture, and it makes us feel full faster. This makes our brains release hormones that make us feel content. In low concentrations, the taste of fat can pair with the other senses to make food more appealing, just as bitterness has appeal in wine, and sweetness has appeal in a piece of cake.

Evolution made fatty acids essential nutrients, but their gag-worthy taste is protective. We typically reject food that has high concentrations of fatty acids, as when a food is rancid. Here, fat is a warning sign to stop you from eating. It’s the expired milk in the refrigerator, the chicken dinner that’s been “left over” too long, extra virgin olive oil used to cook in your frying pan, or the acidic, fishy burp you get after eating, well, bad fish.

The food industry has known about this for a long time, and goes to great lengths to keep fatty acids below detection, because if you can taste them, you won’t eat them. When triglycerides are exposed to light, heat, or oxygen, they break down into fatty acids, their lifespan shortens, and they go bad.

The food industry knows this. So cooking oil suppliers mix their oils to increase profits, restaurants add a rich sauce so they can use older meat, and fish mongers dye the gills, or behead their catch, to mask the parts of their product that could offend, or even harm, the consumer. Overall, if researchers have it right, oleogustus—the offensive taste of fat—is nature’s way of keeping you from eating spoiled food, or over-eating.

More Inspiration: You might also find this article on understanding fats very empowering!

Author: Jennifer Graham is an OptiMYz writer. She enjoys exploring the relationship between people and the body. She is a regular contributor to both our print and digital issues.