[cies]

Humans are bad at lipogenesis: we can only convert tiny fraction of the carbs into fat. Thus: the fat your eat is largely the fat you wear.

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.

[mpreda]

> Humans are bad at lipogenesis: we can only convert tiny fraction of the carbs into fat.

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."

[cies]

Nope. If humans eat both carbs and fat (most of us do), the excess calories of fat goes mainly into the storage (or plaques to your arteries), while the carbs are used in the sort term (converted into glucose).

> 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.

[Attummm]

The human body doesn't need to store excess calories. It could store the excess calories or it can excrete energy through urine(glucose, ketones) Or it can ramp up metabolism, there are many scenarios. Not all lead to adipose tissue growth. Why not muscle growth, which is somehow always overlooked in these discussions.

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...

[Attummm]

Why would a mammal's body evolved to use fat cells to store and utilise lipids for energy?

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

[cies]

> Why would a mammal's body evolved to use fat cells to store and utilise lipids for energy?

Hibernation?

For short term glucose storage is preferred by mammals bodies that i know of.

[thelittleone]

High fat and protein is keto right? What's so dangerous?

[cies]

Ketosis is probably our rudimentary "wintersleep mode". Rudimentary as we are basically tropical animals (look at our lack of fur).

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.

[imtringued]

>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.

[cies]

Short term you can lose weight with ketosis. Long term you are taking unknown risks.

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.

[thelittleone]

For me I went keto because I had a problem with sugar addiction going back since childhood. I managed to maintain a healthy weight through exercise etc but as I aged I felt that my bodies ability to handle sugar was decreasing, and it had significant impact on my energy levels, physical appearance and digestion.

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.

[cies]

I'm glad it works for you. I'm not keto hating, I just find people advising to do it long term to be on the quacky side (there simply is no such evidence).

> Years ago the American diet was supposed to be healthy

The result of lobbying. True nutrition experts knew all along.