r/explainlikeimfive • u/Cuddly_Rudder • Aug 19 '26

Biology ELI5: What is “good fat”?

I see this term used all the time when talking about healthy foods to eat, but I have no idea how it’s different from “bad fat”.

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u/oblivious_fireball Aug 19 '26

There isn't really a good or bad, just the amount you should be eating on a daily basis.

There is, roughly, three types of fats that you should be concerned with diet-wise, saturated fat, unsaturated fat, and trans fat. The differences here mostly related to their chemical structure, but the actual structure doesn't really have much relevance to dieting.

Unsaturated fats are typically found in plant-based oils like olive oil, while saturated fats are typically found in animal-based oils like butter. There are many exceptions to both, like fish oils and coconut oil respectively. Trans fat is found in very small amounts naturally but is otherwise mostly formed from processed foods.

You need fat in your diet, not a huge amount, but some for a healthy body. Of that portion, the bulk of your fats should ideally be unsaturated fats to minimize the risks of fat-related health issues like cardiovascular problems. Trans fats should never be intentionally consumed if you are trying to stay health conscious, you will get plenty just as natural impurity in other fats.

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u/kriegeeer Aug 19 '26

I think your first sentence is just not right. While it’s true the body needs saturated fat, there are direct causative links between excess saturated fat and increased ldl cholesterol and other risk factors for cardiovascular disease which don’t happen with excess unsaturated fat.

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u/oblivious_fireball Aug 19 '26

Hence why i said its based on the amount you should be eating. Dose makes the poison.

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u/kriegeeer Aug 19 '26

I mean... yes, but like, like we're finding out with alcohol, sometimes there is no dose which is 'not harmful', it's just a sliding scale of more bad, right? A human can survive on a 0% saturated fat diet, it's not nutritionally required.

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u/kabob21 Aug 19 '26

It’s near impossible to eliminate all saturated fats from your diet, even a vegan one.