[getpost]

Brad Marshall[0] makes a case for the benefits of stearic acid (C18:0), which is predominant in beef tallow and cocoa butter. It acts as a beneficial metabolic signal that promotes mitochondrial fat oxidation, higher energy expenditure, and leanness—counteracting the obesogenic effects of polyunsaturated fats (PUFAs), especially linoleic acid.

[0] https://fireinabottle.net/every-fire-in-a-bottle-post-from-t...

EDIT: I'm sympathetic to Brad's argument and I'm concerned that RFK Jr's incompetence will interfere with ongoing research in this area of metabolism.

[bloaf]

We all know there has been a replication crisis across many different disciplines of science. I think that the set of things we actually know about nutrition and health is a lot smaller than the experts think.

However, the problem is that the public has also come to that conclusion. The public has gone on to decide "that means my incredibly weakly-evidenced idea is just as good as the expert opinions" which does not follow and is often disastrously wrong.

So I'm also sympathetic to the idea that the saturated fat picture is more complex than a blanket ban suggests. But I know better than to treat things like Brad's arguments as anything other than "interesting hypothesis" as opposed to "something we actually know about nutrition."

[graemep]

I think the experts and the media are to blame.

The public are presented with things that are weakly evidenced as scientifically proven. After all, the one study that says something is good or bad for you was published in a peer-reviewed journal and the university PR people blogged about it and the newspapers reported it uncritically.

A lot of experts are very bad at differing between different levels of evidence and probability: "my personal (if expert) opinion", "a consensus in the field" and "backed by reasonable evidence" and "proven" are very different but all often get presented the same way.

[wat10000]

Experts are usually very good at differentiating between levels of evidence. The process of becoming an expert tends to thoroughly educate a person in just how little they actually know.

The problem is that a bunch of talk about weak studies and probabilities and personal thoughts is not what grabs attention. The few overconfident loudmouths end up being the ones everybody hears from. And you don't even need to be an expert, you just need to sound like one.

If you're a nutrition scientist who really knows their stuff and knows how to talk to people so that they understand just what is really known and how well it's known, how in the world do you compete with someone like RFK Jr.?

[graemep]

> Experts are usually very good at differentiating between levels of evidence. The process of becoming an expert tends to thoroughly educate a person in just how little they actually know.

They know, and are clear about it with their peers but many are very bad at communicating it to the public. There are also experts who are overly attached to their pet theories, or biased, and communicate those things to the public as fact.There are experts who are patronising enough patronising enough to think its not even worth trying to explain things properly to the public.

> The problem is that a bunch of talk about weak studies and probabilities and personal thoughts is not what grabs attention. The few overconfident loudmouths end up being the ones everybody hears from. And you don't even need to be an expert, you just need to sound like one.

All true, Which is why I blame the media as well.

> If you're a nutrition scientist who really knows their stuff and knows how to talk to people so that they understand just what is really known and how well it's known, how in the world do you compete with someone like RFK Jr.?

Good question! The only real solution is better science education, and to keep on plugging away.The most harmful thing is the common perception that experts hand down the truth, rather than understanding the nature of scientific evidence.

[franktankbank]

Lived experience is not really weak evidence though. Personally I use tallow minimally but it seems like a really good high flash point oil.

[technothrasher]

> Lived experience is not really weak evidence though.

Lived experience is definitely weak evidence because it is riddled with bias. This is why we have blinded studies.

[gruez]

>but it seems like a really good high flash point oil.

On what basis? Using the list of smoke point table someone else linked[1], tallow does indeed have a high smoke point, but it's unclear how it's better than many other oils in that list (peanut, sunflower, soybean) which are far easier to procure.

[1] https://en.wikipedia.org/wiki/Template:Smoke_point_of_cookin...

[franktankbank]

Anyone who lives near beef operations can get unprocessed tallow for free.

[gruez]

Most people do not live near "beef operations". Moreover processing tallow is part of procurement. If you value your time at the prevailing minimum wage, it's pretty hard to beat a gallon of vegetable oil for $10.

[Workaccount2]

>Most people do not live near "beef operations".

Yeah, but lived experience shows that a lot of people do.

[pc86]

The entire concept of "lived experience" is, bluntly - absolute bullshit. You take all the worst aspects of both conscious and unconscious biases as well as anecdotal 'evidence', and wrap it up in the fact that the average person is simply not capable of objectively analyzing themselves[0], and you end up with people saying that demonstrably false things are true simply because that's how they [incorrectly] interpreted their "lived experience," or how their "lived experience" supports their decisions. This last part is particularly true with politics and nutrition, where people make decisions not based on objective data but based mostly on how they were raised and what they like.

I can spend decades eating junk food and lose weight as long as I work out long enough and hard enough. My "lived experience" tells me that junk food is fine simply because it hasn't killed me yet.

[0] 80-90% of people describe themselves as an "above-average" driver.

[tbrownaw]

> [0] 80-90% of people describe themselves as an "above-average" driver.

What shape is the distribution of driving ability? It seems entirely plausible that most drivers are decent and a smaller population are bad enough to pull the mean down well below the median.

[Noaidi]

Taking one fatty acid out of a complex fat like tallow and therefore extrapolating that "tallow is good for you and everyone" is a huge mistake.

Does Brad Marshall mention that Palmitic acid is the dominant fatty acid in tallow? And since Palmitic acid is the most abundant SFA in the U.S. diet, can we draw a conclusion that it may partially play a role in poor health outcomes?

PUFA suppress lipogenic gene expression so I do not know where anyone is getting that polyunsaturated fats have and obesogenic effect. [1]

[1] https://www.nature.com/articles/s41467-025-65613-2

[pc86]

Fallacy of composition. It does not logically follow that given Palmitic acid is the most abundant SFA in the US diet (objectively true), and given the US diet directly leads to poor health outcomes (very likely but not proven at least not to the level of the prior claim), that Palmitic acid contributes to poor health outcomes. It's entirely possible Palmitic acid is great for you and if we had less we'd be doing even worse. The statements are simply not connected at all.

[Noaidi]

I was replying to someone who was suing the fallacy of composition.

But if you really want to talk about fallacies, why is no one talking about how genetics can determine who these fatty acids are good and bad for? making blanket recommendation for a specific food without knowing someones genetics and heritage is foolish. But do a search for nutritional genetics on HN....nothing.

[pc86]

> > Does Brad Marshall mention that Palmitic acid is the dominant fatty acid in tallow? And since Palmitic acid is the most abundant SFA in the U.S. diet, can we draw a conclusion that it may partially play a role in poor health outcomes?

I don't know the answer to question #1 but the answer to question #2 is "no, we cannot draw that conclusion" because of the fallacy of composition.