Good question. We probably did most of our evolving when there wasn’t much food around. In those days we would eat whatever was available and store it in our bodies as fat for when there wasn’t enough food.
Now there’s lots of cheap food around and our bodies aren’t very good at telling us when we’ve eaten enough.
Fatty food has lots of energy in it so it’s easy to eat too much.
For decades scientists agreed on four basic food tastes: sweet, salty, sour and bitter. In recent years, scientists also have agreed on a fifth sense, umami, which is evoked by monosodium glutamate (MSG) in foods – this is found in Chinese takeaways amongst other things which may explain why that tastes so good!
Nutritionists and other scientists have said for years that fat only provides texture to foods, and that pure fat itself doesn’t have any taste. Fat has been thought to be a flavour carrier that could deliver taste and odour compounds derived from different parts of food, and as a component that provided texture and what food scientists call “mouth feel” in foods – such as when chocolate melts in your mouth.
But new research indicates that humans can indeed taste fat, which would mean that ability is a sixth basic taste. This could explain why fat-free foods don’t taste as nice as full-fat versions.
Jonathan and Samantha’s answers are really good. I also find that some foods are a bit too dry without a bit of fat, and difficult to chew and swallow. Also, if you fry food in fat it can turn nice and crispy, which is a texture I really like!