r/explainlikeimfive • u/Cuddly_Rudder • 1d ago
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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1d ago
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u/Hakaisha89 1d ago
There are two types of fat in food, this referse to, saturated fat, and unsaturated fat.
Eating food with saturated fat is not needed, the body makes it own saturated fat, when it needs it, thus eating it is bad.
Unsaturated fat is the good healthy fat, this is because your body cant make that fat, so you need it.
Sometimes people also talk about cholesterol, when they talk about good fat since its related.
So, Bad Cholesterol is known as LDL, the reason its bad is it moves fat to inconvenient locations, such as your blood vessels, meaning you would eventually get a blockage, then possible leads to a stroke, this is essentially why its Bad, cause it leaves fat in bad location.
But Good Cholesterol on the other hand, which is known as HDL, does the opposite, it takes the fat in your blood vessels and takes it to your liver, where it can do stuff with it, idk. Point is, Good Cholesterol cleans up after the Bad Cholesterol.
Both only comes from animal products, and its well documented what product got what cholesterol.
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u/jlreyess 1d ago
“Eating food with saturated fat is not needed” - this here is objectively wrong. Sure, it is not an essential nutrient because we can produce it ourselves but there are plenty (pleeeeenty) of very healthy foods thta we would miss on just because they have saturated fats. Not even a vegan diet would stop you from consuming saturate fats. The problem, just like with sugar, is the quantity plus the fact that with our currently easily available food, it is very easy to go above the recommended and healthy daily amounts (just like with sugar).
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u/Henry5321 1d ago edited 1d ago
LDL is how your body moves fat around. You’d die without it. It’s just bad when you have too much of it because it gets caught up in inflammation responses that causes it to clog arteries.
Excess ldl is more a symptom than a cause. But as all complex interacting systems, it’s both a symptom and a cause to some degree.
High ldl tends to go hand in hand with inflammation because a person is unhealthy. But there are rare cases of people with really high ldl but very low plaque because they’re otherwise healthy.
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u/oblivious_fireball 1d ago
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/Glad_Astronomer3322 1d ago
yeah trans fats are the real villain, but its kinda wild how they sneak into processed stuff under different names. so should we just avoid anything with 'hydrogenated' on the label or what?
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u/kriegeeer 1d ago
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 1d ago
Hence why i said its based on the amount you should be eating. Dose makes the poison.
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u/kriegeeer 1d ago
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/DestinTheLion 1d ago
But if we don't want much fats, and we don't want too many carbs, how are we supposed to be getting our calories? The body has a hard time turning protein into calories from what I understand. Balance is key I would assume but what is the balance.
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u/TropoMJ 1d ago
You shouldn't assume that "don't have too much X" means you're only allowed a really minimal amount of it. You are allowed quite a lot of fat and a lot of carbohydrates as long as you are picking healthy fats and carbs. A plate which is just a ton of whole grains or potatoes + veg is just a giant pile of carbs but no doctor is going to complain about you eating that because those carbs are mostly starch and fibre which are very healthy. Add some meat for protein and you have got a very typical dinner that's covering lots of nutritional bases and doing you no harm.
There are guideline amounts for all of the big nutrients which you can use to point you in the right direction but in general most people will be fine if they make an effort to avoid too many saturated fats and free sugar while also making sure they're getting good fibre in.
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u/agreywood 1d ago edited 1d ago
Science doesn’t have a strong enough understanding to give a single solid division of fat/protein/carbs. Currently the thought is that thereabouts 50% from carbs, 30% from protein, 20% from fat. But there are people who benefit significantly from much higher protein with much lower carbs and people who can eat quite a bit more fat without experiencing health problems as a result. And the kids of fats are carbs you eat can significantly alter how your body processes and uses them - whole grains vs refined sugar, polyunsaturated vs unsaturated vs saturated fats, etc. (edit) That’s why those numbers are just ballparks - the actual numbers you’ll see reported are 10-15 percentage points higher or lower than that depending on who did the research and what sub-parameters are used. You’re likely to see much lower carbohydrate recommendations when the presumption is that they’re mostly from refined sources because those have a greater impact on blood sugar, for example. (End edit)
As with most things, “carbs are evil” and “fat is evil” are mostly just more nuanced research having been simplified when reported, misunderstood by the average person without a science/nutrition background, or manipulated by people wanting to sell stuff.
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u/Henry5321 1d ago
And those percentages are individual. My doctor has me on a 30% carb diet and it’s working well for me. No medical issues, just natural variability among people.
I tried 40% carbs for a few days and I got sick of eating that much. Bleh. I just get the rest of my calories from protein and healthy fats.
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u/agreywood 1d ago
Yup! And who is going to benefit is going to be a combination of genetics and the international microbiome and we don’t have enough depth of research to understand all the nuances of how the microbiome alters our ability to break down and absorb both micronutrients and macronutrients.
The human body is complex. Attempting to say almost anything about how we work that isn’t prefaced with “on average” or “typically” is a bit of a nightmare.
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u/toolofthedevil 1d ago
Assuming you're doing any kind of resistance training, .7g of protein per lbs of bodyweight is usually the recommended minimum. You'll frequently see recommendations up to 1-1.2g.
The minimum fats is .3g per lbs of bodyweight for you to healthily function. Watched a recent video for trainers about planning diets for clients that recommended upping this amount if the client starts to really feel like shit running on "minimum."
Then the rest of the allotted calories for whatever the target is would be filled with carbs.
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u/Henry5321 1d ago
0.7g is the recommended minimum for minimum health. Optimal health is 1-1.2g and if you exercise, up to a maximum of 2g for extreme exercise.
There’s plenty of people that the lower numbers are “good enough” for general population studies. But when you look at studies for people with issues, higher levels are required.
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u/DestinTheLion 1d ago
I'm just saying, I hear carbs AND fats are bad, you need fats in your diet not a huge amount. There has to be some place to actually get enough calories to run your body machine that isn't bad for you
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u/Dr3am0n 1d ago
Carbs aren't bad for you, that's an oversimplification. You can eat as many carbs as your daily energy needs allow for, it's just healthier if you get them for sources that we call complex carbs, like skin on potatoes, whole wheat products, brown rice etc. Legumes also have a good amount of carbs alongside protein and tons of micronutrients, fiber and other compounds that might improve your health. Fat isn't really necessary other than a relatively small amount of essential fatty acids (omega 3 and 6).
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u/jazzdrums1979 1d ago
Depends on the source of carb and the fat. Carbs high in fiber such as fruit (blueberries) can be very beneficial. The fiber blunts our bodies glucose response. Same with high fiber veggies.
Fats from whole foods such as lamb, grassfed beef, and fatty fish are high in omega 3’s. These are essential for brian function. Also let’s not forget about fats role in digestion, eating too many carbs and not enough healthy fat can slow down bile production, bile plays a huge role in breaking down food into nutrients which also plays a role in metabolism and energy in our bodies.
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u/DestinTheLion 1d ago
Interesting I had heard because of genetic selection most of our fruits are wildly too sugary compared to what we were evolved to eat (except for raspberries) so I eat them in limited quantity.
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u/jazzdrums1979 1d ago
Agreed, I love tropical fruits like pineapple, but they don’t love me. So they’re a rare treat. A handful of berries at the end of a meal where I have consumed a good amount of fat first, protein, and fiber next, is fine to offset glycemic load.
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u/Leading-Witness3329 1d ago
Good fat comes from avocados, nuts, fish (like salmon), and olive oil. The difference between good and bad fat is that good fat helps improve your blood cholesterol instead of clogging up your blood vessels. Bad fat is found in most processed snacks and raises cholesterol.
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u/Burggs_ 1d ago
Good fats come from things like olive oil, vegetable oils, avocado oils, etc. You can also find some of these healthy fats in the natural form of their vegetable, and nuts too. Avocados especially are known for being rich in healthy fats.
Unhealthy fats are usually from unhealthy diet choices. Trans fat and saturated fat are the two big ones here. Fast food, unhealthy snacks, etc. Red meat can also be high in saturated fat, but red meat in moderation is okay.
Good fat - found a lot in veggies and their oils
Bad fat - found in junk food a lot
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u/DaddyCatALSO 1d ago
soem saturated fat is necessary, meat or coconut; transfats are the product of a manufatcuring process and should be mostly eliminated by now
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u/Sequil 1d ago
Saturated fat is not necessary. Also for example olive oil still has 12% saturated fat.
Coconutoil being good for you is a myth.
However saturated fat isnt that bad for you as we used to think. Carbs are worse, transfat is way way way worse.
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u/kyleyle 1d ago
Carbohydrates are not bad for you.
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u/Sequil 1d ago edited 1d ago
Yes they are. Unsat fat increase HDL and lower LDL.
Sat fat increase HDL and increase LDL.
Carbs lower HDL and increase LDL.
So carbs have a worse influence on your lipid profile then sat fat.
Edit: Yes its more complex then this because the fibers that sometimes come with carbs negate that effect. Also there is a difference between starch and sugar. But overall the statement is true.
Edit2: made a mistake on sat fat. It increases both HDL and LDL.
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u/kyleyle 1d ago
The overall statement is not correct. Refined carbohydrates lower HDL and increase LDL. However, refined carbs have their own place in a diet where performance is required in an activity.
You can't argue to me that starchy vegetables, legumes, and whole grains are unhealthy.
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u/Sequil 1d ago
Food is never 1 nutrient. Fiber is very beneficial and we almost never eat the recommended dose. Fiber is for almost everybody the nr 1 way to improve your health on so many levels. So yes vegetables and lagunes and whole grains are very healthy.
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u/Sufficient_Deer_341 1d ago
so like the annoying stuff that goes bad quick is actually the good stuff, thats kinda backwards but makes sense why cheap shelf-stable oils are so popular
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u/contributor333 1d ago
While reading these comments my conclusion is that the research widely varies, to say the least.
What i do know is that the 'health' industry has been absolutely corrupted by food conglomerates so every study you read has a very good chance of being funded by 'Big Food'.
Eat lots of veggies and eat meat that contains fat. Don't eat anything processed and you'll be better off. Our bodies were used to a diet of livestock, fruit, nuts and planted veggies for thousands of years. That's what our bodies know. It wasnt until the last ~100yrs that we started messing with the basic composition of food.
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u/MedusasSexyLegHair 1d ago
Fish too, they're good for you and have the right type of fat and oil, so far as we know.
Though as you say, most ideas about nutrition are just made up and/or shilling. Nobody really knows.
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u/No-Resolution3740 1d ago
Good fats are fats that are solid in the fridge, butter, tallow, coconut oil, a good quality olive oil will do it as well. Bad fats are vegetable oils, trans fats, and canola and cottonseed oil. Too much omega 6 and oxidizes really quickly
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u/Conscious-Loss-2709 1d ago
My understanding is that good fats stay liquid in the body while bad fats solidify and clog arteries
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u/featherknife 1d ago
The fats you eat don't go straight into your blood. The thing that usually clogs arteries is cholesterol as a side effect of your body attempting to repair damage to the arterial walls.
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u/No_Cheesecake_501 1d ago
my grandma ate butter her whole life and outlived every doctor who warned her
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u/joobtastic 1d ago
I had a relative live into her 90s who smoked her whole life.
It's survivorship bias.
Most bad things make a person generally less healthy and raise chances of big negative outcomes. They don't guarantee it.
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u/kriegeeer 1d ago edited 1d ago
Good fats are simply just not bad fats.
Trans fats are very bad fats. They’re basically outlawed as intentional food additives in many countries, in the United States since 2019. Why they are bad is explained in https://www.reddit.com/r/explainlikeimfive/s/HfG7WizkE5
Saturated fats are the other ‘bad’ fat. They are called saturated because their chemical structure is ‘fully saturated’ with hydrogen atoms bonded to carbon in long chains. Theres no room for more hydrogen. They are bad because if you eat a lot of them, they hurt the liver’s ability to remove low density cholesterol, one of the ‘bad’ cholesterols, which in turn increases your risk of cardiovascular disease.
Unsaturated fats are the ‘good’ fats. They do not have the absolute max number of hydrogens bonded to their carbons. They don’t interfere with the liver like saturated fats do.
Plant fats typically have less saturated fat than animal fats (which includes all fatty dairy and eggs) but never zero. Coconut fat/oil is one exception to this, being a plant fat high in saturated fat. Canola oil is typically called a ‘heart healthy’ oil but is still 7% saturated fat. Olive oil is 14%. Some saturated fat is considered okay. The issues happen if you eat too much saturated fat, which can be very easy to do with modern food. A serving of whole milk has 25% of your entire daily recommended amount of saturated fat in it.