The idea that eating fat leads to higher body fat is the most dangerously-wrong health misconception in history.
Modern equivalent of medieval leeches and enemas for "fever" (almost anything was called a 'fever' back then) and eating goat testicles for potency. Eating them raw obviously :)
While the inverse occasionally has been true, generally people who I consider in good shape appear to eat less, and less greasy food.
So while there might be exceptions it seems to be a damn good rule of thumb to me.
But I suppose that plenty of fats are healthy and part of a balanced diet. And someone who eats nothing but refined sugar is more likely to be over weight that someone with a high % of fat in their diet.
The danger is two fold
1. People don't eat fatty foods which have solid evidence for their benefits (e.g. Virgin olive oil)
2. People substitute the lack of fats with sugar, which I believe (not an expert) has a lot literature linking it with obesity
Your question isn't refuting OPs claim: the people you are observing to be fat are fat because of their carb/sugar intake, not fat.
i.e. if you just fed someone large amounts of protein and fat they would be lean; it is the sugar and carbs that make them fat.
You are right that different foods (macronutrients, more specifically) have different thermic effects and therefore require different amounts of energy to metabolise. Protein takes more energy to process than fat. This does not change my overall point.
The inventor of diet famously lost a contest for being too lean.
You cannot explain it otherwise (without showing a undiscoverd way humans can convert carbs into fat).
> i.e. if you just fed someone large amounts of protein and fat they would be lean; it is the sugar and carbs that make them fat.
This is dangerous. It may work on the short term, but it is very dangerous on the long run.
We should not eat for ketosis. But we can eat (restricted to fat and protein) and still stay in ketosis, which is marketed as the keto diet and is not well tested in long term studies. You are a guinea pig when you do this long term.
As opposed to being reliably obese? What's your baseline? I recently checked the average weight of men and women and I am honestly shocked.
The risks of obesity are well known. Also, you do not get obese by lack of a keto diet. One usually gets there with a rubbish diet.
Keto not only simplified my diet but massively improved my digestion, and helped me form more awareness of risks of sugar.
Regarding no long term studies.. its hard to believe much these days I rely on body feedback. Years ago the American diet was supposed to be healthy, look how that science turned out.
> Years ago the American diet was supposed to be healthy
The result of lobbying. True nutrition experts knew all along.
Because historically food is scarce or difficult to obtain, in general organisms develop mechanisms to make good use of it: when excess food ("energy") is available, it is stored rather than wasted.
This is also true in particular for mammals, and for humans. It's quite obvious that humans are very effective at storing excess energy.
It is said that sumo fighters maintain their body mass (muscle + lots of fat) by eating rice (i.e. carbohydrates) and protein.
Lipogenesis (fat generation from carbohydrates) takes place mostly in the liver. "Excess acetyl CoA generated from excess glucose or carbohydrate ingestion can be used for fatty acid synthesis or lipogenesis."
https://courses.lumenlearning.com/suny-ap2/chapter/lipid-met...
The conclusion being: "Humans are great at lipogenesis. That's how we store excess energy."
> Lipogenesis is mostly derived from carbohydrates and is a relatively minor contributor to whole-body lipid stores, contributing 1–3% of the total fat balance in humans consuming a typical diet.
From:
https://www.sciencedirect.com/topics/agricultural-and-biolog...
Believe what you will. "It is said" wrt sumo fighters does not sound very scientific.
Funny enough adipose tissue and muscle growth are both through hormones. If testorone and hgh are high then muscles growth will prioritised over adipose tissue.
People with type 1 diabetes have figured out how to stay thin after eating copious amounts[0]. They won't inject themselves with insulin. Unhealthy, sure, but they won't store calories, as adipose tissue (fat cells) remain inactive, even though blood glucose is dangerously high.
Just looking at calories is simplification, and is just for general guidance.
[0]https://my.clevelandclinic.org/health/diseases/22658-diabuli...
Plants have carbs in starch. Mammals evolved away from starch to store and use triglycerides.
During fasting, the human body is able to survive for months without food.
Thus months of lipid metabolism
Hibernation?
For short term glucose storage is preferred by mammals bodies that i know of.
A large amount of protein would make them fat - experiments have shown that about 8% of ingested protein gets converted to glucose in the liver:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3636610/
The authors calculated that ∼18 g (79%) of the 23 g of ingested protein could be accounted for by deamination; thus those carbon skeletons were available for gluconeogenesis and release of new glucose into the circulation. The remainder, presumably, was used for new protein synthesis.
The total amount of glucose entering the circulation from all sources was calculated to be 50 g over the 8-h period. However, only 4 g (8%) could be attributed to the ingested protein.Cholesterol levels don't track intake directly. Lowering cholesterol and fat in diet needs to be done in consultation with somebody who understands your metabolism. Some vitamins are fat soluble. Some fat is beneficial.
Homeostasis is amazing.
The lymphatic system is also involved.
So it's not entirely "eat as much fat as you like" by any stretch. It's more that over time, the body tends back to a baseline model. Continual high levels of fat which cause surplus in the bloodstream are heading to arterial blockage and isn't good, but the relationship of fat ingested to fats in the blood is a more complex path. "it depends"
I'm not a bio scientist or a med. Happy to be corrected.
Are they eating fat _or sugar?_ The body will aggressively squirrel away any unused sugar as fat. As one example, a Big Mac contains 7g of _added_ sugar. Fries? Coated in dextrose. Sugar is added to damn-near everything.
I believe most people gain excess body fat through eating a little bit more than they need each day and then two or three weeks a year they eat and drink much more (holiday, Xmas, birthday etc), rather than consuming vast amounts of food day in day out of the wrong macro nutrient make up.
A calorie is measured by burning food a specific distance away from a specific amount of water and measuring how much the water temperature rises. It's based on an assumption that the body uses all energy in the food the same, and that fire is analogous to the complex process from digestion to energy use in the cell. The calorie as a measure effectively equates the body to a coal power plant.
Anyone who tracks their calories daily for a long period of time will see that when they eat more they gain weight, when they eat less they loose weight.
Like I said above, there are other aspects that can factor but “calories in calories out” accounts for 80% of weight loss and weight gain (applying the broad brush of the 80:20 rule)
That is simply not true for people that are already obese.
We can't simply burn food and deem that an accurate analog to how the body processes and utilizes different food. Ask anyone that live(d) primarily on rabbit meat.
And to be clear, the 80:20 rule is am extremely broad and inaccurate rule of thumb that isn't useful when applied to something specific. You can't claim that calories in equals 80% of calories out because Paredo.
perhaps not coincidentally, this variant also comes with a higher risk of Alzheimer's disease
At the high level, my basic claim is that the idea that dietary saturated fat directly leads to heart attack is incorrect. The history of this claim dates back to President Eisenhower. After having a heart attack while in office he wanted to tell the public how he could avoid the same fate. Researchers cut corners to meet political targets, ignoring data that disproved their hypothesis and claimed that plaque found in cadaver arteries was made of saturated fats and that it got there due to the person's diet.
The claims weren't backed up by the studies used and we were told that this was now a known fact when it wasn't. We've spent many decades since avoiding saturated fats in favor of unsaturated fats, which are highly oxidative and have concerning side effects when run through the Krebs Cycle.
Dr Eades also has a few interesting talks on the subject when he walks through the Krebs Cycle and the difference of saturated and unsaturated fats in case that's helpful. I think [2] is one I watch years ago, though he has other similar talks on YouTube as well.
[1] https://proteinpower.com/ [2] https://www.youtube.com/watch?v=7MTNJNAZPiw