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Why We Get Fat

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“Calories in, calories out”, and its natural conclusion, “just eat less and move more”, is not a useful way to think of obesity and it’s not helpful advice.

Just eating less rarely helps. If you limit your energy intake below your energy expenditure, yes, you’ll likely lose weight, but it’s unsustainable. You’ll have less energy available, you’ll feel exhausted and half-starved, and the moment you stop, you’ll bounce back up.

Just move more rarely helps. Physical activity is good for health, and there is some evidence that going from complete sedentary lifestyle to some physical activity helps. But it’s unlikely that, above that threshold, physical activity will be much of a help in weight loss. Sure, you’ll burn energy, but all it will do is create a energy deficit your body will balance with appetite. Unless you half-starve yourself (again, unsustainable), you’ll just end up naturally eating more to counterbalance the energy expenditure. So instead of running up the stairs and eating an extra slice of bread, skip the stairs and skip the bread.

Biology, not math

“It’s simple math!”, they say. “It’s all about energy balance”. Is it?

Of course, “calories in, calories out”, on some level, must be true. The law of energy conservation. But that doesn’t mean it’s a useful mental model. It doesn’t say what happens with the energy intake, it doesn’t say what motivates the energy intake, and it doesn’t say how expenditure influences intake or the other way around.

Stop thinking about obesity as a disorder of energy balance.

Obesity is a disorder of fat accumulation. Duh!

Biology, not math.

How is fat regulated?

Body fat is in constant circulation. It flows out of and back into fat cells all the time. And what regulates the balance is primarily insulin. High level of insulin suppresses fat flow into bloodstream and mobilizes proteins that shove fat back into fat cells. Low level of insulin does the opposite.

Okay. What controls the level of insulin? Glucose.

Low level of glucose means low insulin. High level of glucose — high level of insulin. It is a complex system, of course, but primarily, and in a healthy organism (diabetes complicates things), this is it.

See, here’s the thing. Glucose is both necessary and toxic. Red blood cells need glucose for energy, as they can’t burn fat. And our brain, generally, also lives on glucose. But high level of glucose is also toxic. So, when there’s a spike of glucose, insulin is mobilized to get that glucose out of the bloodstream — putting it in the liver, in the muscles, and in fat cells. And the fat that’s also in the bloodstream — yup, that goes right back into those fat cells.

Glucose and carbs

So what controls glucose levels? Pretty much just one thing: the amount and kind/quality of carbohydrates in the diet. Sure, the organism can make glucose out of fat or protein when it has to, but that won’t make glucose spike, and it’s those spikes that are the biggest reason for excess fat to be stored, for that fat inflow not being in balance with fat outflow.

So, carbs are bad. Kind of. There’s many kinds of carbs:

The new diet

And here’s the kicker:

Don’t try to control the amount of food to it. Just don’t do it. It won’t help in the long term. It will only make you miserable and when you’ll crave food, you’ll want to eat precisely the kind of food that makes you fat.

Eat as much as your body tells you to. Not more, not less. Of course, don’t overeat or stuff yourself after you’re full. But when you’re hungry: eat. And eat regularly (5 times a day is better than 3 times a day).

Your body gives you appetite for a reason. It’s the fat regulation, not energy regulation that was broken. If you change your diet to correct fat regulation, your body should do a good job at signaling energy needs.

Again: you don’t have to care about food amount. But you must control the kind of food you eat. (Which makes weight loss dramatically easier to accomplish and sustain).


More on metabolism

(some of this stuff I learned after the book)

Most of the cells in your body can burn fatty acids directly quite easily. But your brain can’t.

So when you cut carbs enough, your body will switch from glycolysis (burning energy primarily from glucose) to ketosis (burning from fat). In ketosis, your liver will convert fat into ketone bodies, which can flow through the blood—brain barrier, and then it can burn energy from ketones.

That’s what your body is doing when you’re asleep. Glucose is low because you haven’t eaten in hours, so it’s in mild ketosis, burning fat (and converting fat into ketones, and also burning that) instead.

Your body doesn’t process carbs, protein, and fat the same way. Sure, it can convert fat into glucose. But it’s a very inefficient process (only the glycerol part of a fat molecule, not the fatty acids, can be converted into glucose), so it’s not done a lot, and fat won’t trigger insulin response the way refined carbs (processed right into glucose) do.

Regarding fat accumulation and carbs, there are two factors in play:

Sugar (sucrose) is literally addictive — pushes the same buttons in your brain as many drugs. So while your body does a good job generally at signaling hunger, you might crave sugary stuff in particular even when you don’t need it at all. Like any addiction, it gets easier with time if you stay mostly away from it. Just don’t even buy sweet stuff to avoid the temptation. (Power of Habit — create an environment in which doing the right thing is the easiest option).

Estrogen and testosterone have a suppressive effect on the protein that pulls fat into fat cells. So as you get older and your estrogen/testosterone level gets lower, it really is harder to stay lean.

PS. Those are just my notes from the book and subsequent research. I’m no expert, use at your own peril, yadda yadda yadda. But this, this really helped me. And this works for me in a way other things I’ve tried before never have.

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