Fats have low freezing points and high freezing points. Lard (mostly saturated) has a high freezing point because it's solid at room temperature. Fish oil has a low freezing point. If fish oil (mostly unsaturated) had a high freezing point the fish couldn't move in water.

This depends on the shape. Saturated fats are long and stack on top of each other, making them solid easily. Monounsaturated/polyunsaturated just talks about the amount of double carbon-carbon bonds. So a carbon would attach twice to another carbon rather than having a hydrogen. These fats are crinkly shaped and have bends in them because of the double bonds. Trans fats change the orientation of hydrogen so that they're straight rather than crinkly and subsequently solid at room temperature rather than liquid.

I don't know the exact mechanism of why trans fats are bad, but it probably has something to do with them not normally being found in nature and them being straight, possibly making the body think it is a saturated fat. Just small structural changes have a big change in effect. Thalidomide, for example, was dangerous because its isomer inhibited blood vessel growth.

Now consider the diet of modern seed oils, where the majority of it is monounsaturated and polyunsaturated fat. The industrialization that allows for humans to collect a bunch of tiny seeds and squeeze all the oil out of them has existed for only a few hundred years at most. Crisco was made out of cottonseed oil, which (1) has a ton of trans fats from the hydrogenation process, (2) naturally has gossypol, a compound in that causes male infertility. Plants have a lot of compounds for natural defense. Nobody eats raw cassava because it has cyanide compounds. Only through methods such as fermentation (think cow + lumen), sun bleaching, heating, boiling, grinding, selective breeding etc. can many plant components be converted into nutrition. Egg white also has a lot of natural defense compounds/proteins, which is why egg yolk is less reactive than egg white for those with autoimmune issues.

Since unsaturated fats have double carbon-carbon bonds, it's easier for them to react with things at high temperatures. Since trans fats are now banned, vegetable oil is fully hydrogenated and interesterified. It's possible that fully hydrogenated vegetable oil isn't bad for people, but it's a comparatively new process and I wouldn't want to be the one testing it out. It's possible these processes also introduce unknown toxic substances.

In the past, people used lard, butter, tallow, or in tropical regions coconut/palm. I highly doubt something so historically used is as dangerous as something that's been created in the past hundred years, but the diet of pigs and cows are now also changed to a primarily grain fed diet, which may change their fat composition.

If you look at a lot of nutrition science, the original studies are bullshit. Not untrue, but just that they're wildly distorted. I don't consider a rat eating a processed diet and subsequently isolating a compound, then calling it a vitamin or an essential fatty acid, is in any way generalizable to humans. Now people tend to propagate things like "this has a lot of omegas," etc. without understanding the historical basis of it.

Note that there are nutritional deficiencies such as beri-beri, mangelwurzel, pellagra, B12 deficiency, that are true and real. I'm not denying the existence of vitamins. But they should not be a concern to anyone eating a diverse diet. People should avoid vitamin supplements and (1) eat enough, (2) eat with diversity, and these nutritional deficiency diseases should only be a second thought.

My current thoughts on good health practices are as follows:

- eat enough

- don't eat raw food or plants

- avoid seed oils

- avoid overly processed salted or smoked meats/vegetables

- exercise

- get enough sunlight

- don't eat liver (Tends to be the biggest accumulator of toxins in the body. Why would you eat something meant to filter out toxins? Risk of hypervitaminosis A over a long period too. Limit preformed vitamin A, such as skim milk in the USA. I don't think it's a good additive based on my research. I'm not particularly concerned about water soluble B vitamin additions, water, iodized salt, etc. but may do some more research into it later)

- don't take drugs whether they be statins, birth control, painkillers, anti-allergy, etc.

- cooking in safe pots/pans (not sure what yet, still doing research) (copper + acid = copper leaches out, non-stick degrades at high temperatures, aluminum I've heard is dangerous)

- avoid breathing in car exhaust (it's hard, but I've suspected the air quality in cities even in developed countries is much lower than people believe it is)

I might've forgotten a few here or there. A lot of pesticides accumulate in things such as eggs and milk (noted from Silent Spring). But they're probably fine in limited quantity.

The crux is that seed oils are not dangerous in small amounts, evidenced by people eating it just fine. Rather, they may be cumulative and its effects show up much later in life, so it's hard to pinpoint cause and effect.

I strongly believe that cancer, autoimmune diseases, metabolic syndrome, and other modern diseases have a definite cause and are not just "genetic" as some say, which is a hand-wavey way of minimizing culpability and lets people do nothing about it.

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