I know there are some very astute members in this forum so I’m curious to see if they can answer this question. I posted earlier in the week about how we can draw on "unlimited " energy stores when we have a physiological limit of using a certain number of calories per day per pound of body fat. It was also pointed out our bodies produce endogenous glucose that we can utilize as well. So my question is, what happens in the following scenario: say you consume a large amount of energy one day, more than usual but still taking in macros that fit within staying in ketosis. Then you fast the next day. Does your body use the extra energy from the previous day during the fast or does it still draw on stored energy? I find that if I eat a lot one day, I’m able to fast for 24 hours without issue, including working out, where normally I can go about 16 hours before I have to break my fast when consuming a more typical amount of food. I don’t have much body fat, about 10 pounds, so I can’t go for very long without extra fuel. Can I fast longer when I comsume extra food the previous day? I have done things like eaten what I know is a high amount of carbs and protein, maybe 100 grams of carbs and 150 grams of protein, then fasted all the next day, and my ketone levels are excellent during that time and I feel great. Just curious about why this happens since I generally can’t really fast for long.
Physiology of fasting/using stored energy
I suspect that while our brains tend to think in 24 hour cycles out bodies and metabolisms work more on a law of averages system.
I have no scientific basis for my thoughts. Just ole farmboy intuition.
Great Question BTW!
It will store the energy.
The way I understand it, the increase in food the day before will top off your muscle glycogen stores. Nomally, it would use body fat to do this if you didnt eat, putting a strain on the overall system (in your case). The fat you eat only remains in your digestive tract or blood for a matter of hours, except for about 25g. It is stored away in the available pool of body fat. Consuming some fat immediately before exercise might give you more available energy.
If you were loading glycogen into your liver for quick use, like in carb loading, it would shut off ketogenesis. There might be a delay where ketones are still in your blood and not being used, and if you didn’t fast the next day you may indeed be out of ketosis then.
It’s fascinating to me that my body tells me very clearly that it is not hungry the day after eating way than usual. It’s like it is telling me it doesn’t need anything because I’ve got enough on board, whereas other times the day after I eat a “normal” amount I start to get really hungry around noon. This way of eating is vastly different in its implementation once you become very lean and active than it is when you have a good amount of weight to lose and want to reverse disease. It is AMAZING that keto resets our hunger signals to the point where we know exactly what we need. It also amazes me that someone who has large amounts of stored energy to draw on can fast for days without issue where my body knows it’s stores are low and tells me I can’t go to long without extra fuel. Very cool
Your circulating lipoproteins are a short term store of extra lipids. So the LDL still circulating carrying energy left over from the day before is supplementing your body fats contribution. The second day (24-48hrs) is probably down to body fats contribution and burning protein to make up your arrears. Which would be bad
Wow that is fascinating!! Always an endless source of information Richard!
Have we figured out just how much there is in the intermediate reserve of circulating cholesterol? I saw a study that indicated about 25g of FFA on average. I guess it depends on your LDL levels that day? And that is actually lower if you are eating extra sat fat for a few days. But maybe if you pig out for ONE day the level would increase?
I may be slipping on some terminology here @richard @DaveKeto
Yes, @richard and I have chatted about this a couple times. I’ve had a crazy theory for a while that the body may actually be upregulating LDLp as a kind of alternate glycogen store (since it knows my actual glycogen stores are generally lower from being low carb). But if true, it wouldn’t likely be very long term relative to adipose tissue.
But overall, this is a very, very difficult question to answer given how many systems are in play at any given time. The best way to get a sense of your body’s intended global metabolic actions is via hormones being moved through the blood – but there’s not really a good way to get that on the fly.
(One day we’ll have biodevices that give continuous insulin monitoring, and that will be a very validating time for us low carbers. :D)
This seems logical, any development of the theory or research suggesting this might be true? It would definitely explain why some people, like myself, see very high LDL even though it is non-atherogenic Pattern A.
Actually, yes, I have some very suggestive evidence given my distance running in the last four months in particular. But it is still preliminary and I can’t go into it just yet as everything is being focused on the upcoming presentation for Breckenridge.
Afterward, however, I’ll be doing one more experiment before then shifting to weight training – where I’ll be able to get even deeper on the lipid metabolizing (and catabolizing) in response.