Weight loss or gain is so complex

(Bob M) #1

Was reading this new Gary Taubes article:

Highly recommended, of course.

He’s got this paragraph near the end:

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So, I went to the cited study (behind a paywall, unfortunately):

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https://www.nature.com/articles/s41591-019-0565-5

That’s an amazing concept.

Lipid removal rate decreases during aging, with a failure to reciprocally adjust the rate of lipid uptake resulting in weight gain. Substantial weight loss is not driven by changes in lipid removal but by the rate of lipid uptake in adipose tissue.

I can’t quite contemplate what this means. It has to have an insulin component, as this is what limits (lower insulin) lipid uptake. (Is there a role for PUFAs here too, to encourage more uptake?) But to say that losing weight is a function of a lower rate of fat uptake…that blows my mind.

(Bacon is a many-splendoured thing) #2

More from Taubes:

For researchers and public health authorities to make real progress against obesity and the obesity‑diabetes epidemics, they will have to shed their energy-balance thinking, their obsessive focus on how much people eat and exercise. Instead, borrowing again from Hilde Bruch in 1957, they’ll have to focus on fat metabolism and storage itself, “since by definition excessive accumulation of fat is the underlying abnormality.” If they think of obesity as it simply and clearly is, a disorder of excess fat accumulation, they might actually figure it out.

This makes sense. Berson and Yalow said that for fatty acids to leave adipose tissue “requires only the negative stimulus of low insulin.” To me, therefore, it makes great intuitive sense that people on a high-carb diet, becoming more insulin-resistant as they age, see their rate of lipid uptake increasing along with their average insulin level. A low-carb/keto diet would (does) reverse this trend by lowering average serum insulin, thus slowing uptake and permitting removal.

(Bob M) #3

Good points Paul.

This is where it would be nice to see how they actually did this, because one would think what you’re eating influences whether or not your fat gets “trapped”. It’s the whole Gary Taubes’s idea of the starving fat man, where the man cannot access his own fat due to insulin “locking” calories into the fat.

When all you have is the abstract, though, it gets tough to analyze.

And I guess it’s more like insulin directing calories into the fat, as (unlike what I used to think, and what most people think) fat is much more dynamic than what’s thought.

It’s more like a huge arrow/pathway pointing into the fat, and a smaller arrow/pathway coming out of the fat. I think this is how low carb/keto works: it changes those arrows so the arrow out of the fat is bigger. You have access to more fat, and therefore less hunger.

(Bacon is a many-splendoured thing) #4

And another cause of less hunger is that the lowered insulin stops blocking the effect of some of the appetite hormones (I believe high insulin keeps us hungry so that we can store up fat to live off while hibernating—if that makes sense).

As for the arrows you mention, part of moving the large arrow to the outflow is what Benjamin Bikman calls “metabolic uncoupling;” i.e., the adipocytes start metabolising more fat than they strictly need to survive, thus in effect revving the metabolism and wasting energy.

(Bob M) #5

Is this a brown fat hypothesis?

(Bacon is a many-splendoured thing) #6

What precisely the distinction is between white adipose tissue and brown adipose tissue, I am not actually sure, except that brown adipocytes routinely use lots of extra energy, while white adipocytes routinely do not.

If I’ve got it right, we all start out with brown and white adipocytes as babies, but we lose the brown ones at some point after babyhood. On the other hand, however, our white adipose tissue can, under the right circumstances (such as a ketogenic diet), start behaving like brown adipose.

But apparently the white adipocytes never become brown, they just act as though they have, hence the “beige” moniker. Go figure.

(Butter Withaspoon) #7

How brown the fatty tissue appears is a result of the mitochondrial density in the cells. Brown fat cells have more mitochondria, lots of little black dots that darken the tissue.

My memory tells me that energy uncoupling, occurring in the mitochondria, can happen in more than just the fat tissue. I remember observing it in mammalian liver cells for example

#9

And you can be banned for being a troll! BYEBYE!