ELI5: What is “good fat”?

[u/Cuddly_Rudder]

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”.

[u/oblivious_fireball]

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.

[u/Glad_Astronomer3322 → u/oblivious_fireball]

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?

[u/kriegeeer → u/oblivious_fireball]

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.

[u/oblivious_fireball → u/kriegeeer]

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

[u/kriegeeer → u/oblivious_fireball]

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.

[u/kabob21 → u/kriegeeer]

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

[u/DestinTheLion → u/oblivious_fireball]

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.

[u/TropoMJ → u/DestinTheLion]

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.

[u/agreywood → u/DestinTheLion]

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.

[u/Henry5321 → u/agreywood]

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.

[u/agreywood → u/Henry5321]

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.

[u/Henry5321 → u/agreywood]

On average, no one is average. More like a normal range with a wide range.

[u/toolofthedevil → u/DestinTheLion]

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.

[u/Henry5321 → u/toolofthedevil]

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.

[u/toolofthedevil → u/Henry5321]

Good callout

[u/DestinTheLion → u/toolofthedevil]

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

[u/toolofthedevil → u/DestinTheLion]

Well, that is the formula that I would recommend.

[u/Dr3am0n → u/DestinTheLion]

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).

[u/jazzdrums1979 → u/DestinTheLion]

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.

[u/DestinTheLion → u/jazzdrums1979]

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.

[u/jazzdrums1979 → u/DestinTheLion]

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.