Simple question - I think

[kib]

If a person is in ketosis and they consume quite a lot more fat than they need during a low/no carb meal that doesn’t spike insulin, what happens to the excess? Does it simply circulate in the blood until it can be burned? Is it stored (by what means?) Or is it somehow excreted?

[Anniegirl9]

I’m not sure about all of it, but I do know at least some is excreated. That’s what shows up on ketone sticks you pee on. If you’re like me, I’ve had super high ketones from day 3 or 4, and it hasn’t gone down much. That’s because my body isn’t fat adapted yet, so it isn’t using the ketones for energy efficiently and I’m showing them in high amounts in my urine.

[PaulL]

For one thing, that’s what “eating fat to satiety” is about, pegging your caloric intake to your body’s energy needs. Since fat is very satisfying, if your satiety signaling works, you are are going to find yourself losing interest in food and not wanting to eat too much. Granted, the stomach still has plenty of room at that point, but eating past satiety is not easy.

If your satiety signaling doesn’t work right, then you have a problem, of course. You could well end up eating “too much” fat. But there are two points to consider: first, there are well-documented cases of people who consumed 3,000 to 5,000 calories daily and still lost weight. I’m not saying everyone can do that, but it does tend to suggest that eating fat to satiety is not going to prevent us from losing weight. Second, in the presence of abundant energy, the body ramps up the metabolic rate and wastes energy in the form of heat. Even the fat cells can start to burn fat, as Dr. Bikman points out.

So, paradoxically, a high daily energy intake can actually encourage the body to expend more. Furthermore, the brain is a tremendous energy-hog, compared to the other organs, and so a copious supply of beta-hydroxybutryate can help produce that wonderful clarity and mental energy people often experience in ketosis.

I think that these considerations indicate that “more fat than we need” can actually be harder to achieve than we might think.

[kib]

Thanks Paul. Ironically it’s the Bikman video you posted in the cold showers thread that answered my question, at least partially. In the absence of insulin, excess lipid in the diet converts to ketones and is either burned by the body for work, burned by the body for heat (which is ramped up in a keto state), or ‘wasted’ - excreted in the breath and urine. That may not be 100% of the story but it goes a long way to eliminating the CICO conflict. We’re not actually circumventing the laws of thermodynamics after all.

ETA: I find this to be a relatively simple argument for the CICO people. “You’re right, calories in do have to equal calories out. But if the excess calories I take in are fat, they are burned or excreted. That’s the extra “out” that accounts for weighing less. If the calories I take in are carbs, the excess is stored in my body.” Utterly simplistic but an explanation third grade math can appreciate.

[PaulL]

That’s right. What the CICO people fail to take into account is that they assume casualty runs in one direction, when it actually runs in the other. We take in more energy than we expend because our fat cells are busy storing fat, not the other way round.