Burning body fat. What? All of it?

(David) #1

So my Wenchie has been being low carb for a couple of weeks now and doing great since her visit to see me, and she’s reading and researching and came across annoying podcasts where there was half an hour of some girls going “you were great, you’re doing fantastic” and fawning all over each other and then she found a great one called 2KetoDudes which she loves because of the science-based ethos. So she’s (as of this moment) listening to show 1. She says she likes “the Australian guy. He’s nice”.

Anyway, she was talking to her boss about it and she was asked “so if Keto burns all body fat, even though we eat some … how does it stop? Or, is the end result a body with no fat at all?”

Well, she didn’t know how to answer that, and I can’t imagine any body (even a servely deranged one) having no day at all. So, what do you think guys? How does the body decide not to burn any more body fat, and where would it get its energy from?

(Allie) #2

That’ll be why it’s recommended to increase dietary intake as you get close to your goal I guess, though the body does know how much it needs to hold on to.

#3

I think that this presumes normal levels of insulin where lipolysis isn’t inhibited, otherwise fatty acid oxidation will be suppressed.

The only example I can point to is starvation where at some point, body fat is too low and then it begins to catabolize lean body mass unfortunately, but that’s actual starvation.

I suspect that under normal circumstances, the body will just ramp up hunger signals and “force” the person to eat.

So given the qualifications above, I would say that the body stops burning fat when it runs out and then starts to burn lean body mass.

I would be interested in the actual mechanisms that the body uses to increase hunger signalling based on dwindling stores of fatty acids in adipose tissue.

(Barbara Greenwood) #4

That’s got to be it. Otherwise humans would have gone extinct.

#5

There will be a point where weight loss will plateau out - even on keto you’ll be producing some insulin, complete absence of insulin is type 1 diabetes. You see with type 1 diabetics that before treatment they’ll lose weight alarmingly no matter what they eat.

There’ll also be a point where your body’s energy matches the energy you’re putting into it. Your body can force the issue and slow its metabolism if you’re consistently underfeeding it. There was an interesting 2 Keto Dudes podcast about this recently.

(Michael Wallace Ellwood) #6

I’d say it’s actually quite difficult for a human to starve themself to death.
The exceptions are of course the extreme cases of concentration camps, some wartime prison camps, famine, and individuals on hunger strike.

The exceptions to what I wrote above are I suppose those cases that we know of where people have deliberately fasted for very long periods, apparently without harm. They were doing it for a specific purpose and were presumably well-motivated, initially motivated to start fasting and keep on doing it, and then motivated to stop at what they deemed to be the right time.

The exceptions to the exceptions would perhaps be anorexics, who are not well-motivated. They are suffering from some kind of illness that isn’t the same (I don’t think) as the metabolic disturbance that we overweights (etc) are suffering from. Perhaps in the case of anorexics, they are suffering from a disturbance in those normal mechanisms that signal hunger and “eat now” to most of us. (There may be a psychological component too, of course).

(Barbara Greenwood) #7

I think you can discount prison camps and famine - those people would eat if food were available. Voluntary starvation is possible (hunger strikes, anorexia) - but exceedingly rare.

(Siobhan) #8

After a point, your insulin sensitivity will return and basal insulin will reach a normal, blocking off access to your emergency reserves, as far as I am aware. Your weight will then stabalize. If you get too low on fat, ghrelin will be released to make you hungry.
Your energy then will be coming from food and not body fat. Except for extreme emergencies like I dont know your car breaks down in the middle of a desert or something.
If you get too low on energy you will get hungry and eat.
You would still be doing <20g carbs per day (or whatever it was before) moderate protein (for maintaining muscle) and the rest of the energy to function would be dietary fat, just maybe more of it.

Basically your body has a range of fat it wants you to be in (22% bare minimum for women) and once it enters that range hormones help homeostasis by leptin (full), ghrelin (hungry), energy expenditure (depending on calories in more or less may be used up), and so on.
The body knows what its doing!
It is only with very rare disorders that people use up ALL of their body fat.