Ketosis starting time

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newbies
extendedfast
(Stephen ) #1

Hi everyone. I am 33 years old doing 72hours fast now. I have a question: I ate deep fried tempe, egg boiled, sauteed mustard leaves and sauteed spinach for my last meal. Does ketosis start exactly 48hours after my last bite, or 48hours after the stomach finished digesting our food? Thanks before guys.

(Gregory - You can teach an old dog new tricks.) #2

Take a look at:

The complete guide to ketosis

Scroll down to: 7. Signs that you are in ketosis

Where did you get the 48 number?

Seems rather arbitrary…

(UsedToBeT2D) #3

Actually, it’s exactly 47 hours, 16 minutes, 34 seconds after last bite. Give or take 72 hours.

#4

It starts when you run of out stored liver glycogen. There’s no clock on it other than your metabolic rate.

(Stephen ) #5

Hello @OldDog. Thank u for responding.
This is the article:
https://europepmc.org/article/med/371355

(Michael - When reality fails to meet expectations, the problem is not reality.) #6

@Stephen1 link: Advances in Experimental Medicine and Biology, 31 Dec 1978, 111:169-188. This is a chapter in a book. Although I suspect we know more about it now than 40 years ago, from what little is displayed it seems overall still quite relevant. Unfortunately, I could find no link to the full text of the chapter, only payfer links. At any rate, I find this statement interesting:

…Amino acids in excess of those needed for protein synthesis are preferentially catabolized over glucose and fat for energy production. This occurs because there are no significant storage sites for amino acids or proteins, and the accumulation of nitrogenous compounds is ill tolerated…

Since amino acids require lots more energy input to digest/process, my understanding is that metabolic utilization of proteins for energy is the last resort. This also results in protein sparing as long as possible. I guess it depends on the meaning of ‘excess’. Some of us calculate our protein macros fairly rigorously based on LBM or gross weight and others very liberally - some carnivores claim to eat more protein at a single meal than most other folks eat in a day or two. I guess one would have to measure urea concentration in urine to determine at what intake ‘excess’ occurs.

(Bacon is a many-splendoured thing) #7

Firstly, that article is talking about fasting, which is a bit different from eating a well-formulated ketogenic diet, although the two conditions are similar in a number of ways.

The answer to when ketosis begins depends on the situation. Essentially, the answer is that it begins when blood sugar and stored glycogen run low enough to trigger a process in the liver called gluconeogenesis (which is basically Greek for “the making of new sugar from scratch”). Gluconeogenesis and ketogenesis (the making of ketone bodies) are controlled primarily by two hormones: glucagon and insulin. They are both manufactured in the pancreas, in regions called the Islets of Langerhans (who first described them). The islets are made up of two kinds of cells, labeled α (alpha) and β (beta). The α-cells make glucagon, and the β-cells make insulin. The two hormones regulate each other, in a very interesting kind of dance.

The upshot is, however, that in low-carbohydrate dietary conditions, glucagon is more active, and it promotes gluconeogenesis and ketogenesis in the liver. So when we eat very little carbohydrate, or when we fast, there is a need for a certain amount of glucose in the body (not much, but some), and then the body uses ketone bodies for many purposes. In conditions of high carbohydrate intake, insulin predominates and shuts off gluconeogenesis and ketogenesis, so that all the excess glucose in our bloodstream gets taken care of (it is either metabolised or stored as fat). Depending on whether you begin fasting from a low-carb or a high-carb diet, the time it takes for ketones to start being produced will be different. If you are eating a high-carb diet and switch to a low-carb one, I imagine it would take a day or two for insulin to drop and for the body to start making and using ketones.

The authors of your article may have observed a measurable rise in ketones after 48 hours of fasting (I only read the abstract), but that is probably an average over all the subjects they studied, as I would expect quite a bit of individual variation in this matter. Past the initial stage of running out of glucose, however, the body is pretty much in ketosis, as long as carbohydrate intake stays low enough. As a forum member wrote, a while ago, “you know you are in ketosis as long as you are (a) eating very little carbohydrate, and (b) still breathing in and out.” (I wish I could remember who wrote that line, because I love to quote it.)

(Michael - When reality fails to meet expectations, the problem is not reality.) #8

@Stephen1 This might be helpful in addition to Paul’s explanation. I started keto with a 4-day water fast. On day 2 of the fast I felt extremely hungry. I compare it to the flesh eating plant in the film Little Shop of Horrors which continually demands to be fed NOW! On the morning of day 3, it was different. The previous day’s ‘carb hunger’ was replaced by what I call ‘keto hunger’. Keto hunger is more like the treasurer at a monthly board meeting announcing that last month’s outgo exceeded income and the difference had to be made up out of cash on hand. Ho hum.

(Stephen ) #9

Thnaks for explaining so well Paul, I like the quote on the last sentence. Hahaha

(Stephen ) #10

@amwassil you really make me want to extend my fasting to 4days. Hahaha

(Michael - When reality fails to meet expectations, the problem is not reality.) #11

@Stephen1 One of the motivations of extended fasting, by which I mean 3-4+ days is the amazing feeling of ‘physical purity’ one begins to feel. Pre-keto I once did a 14-day fast and after the first several days not only was I not particularly hungry, but I did not want to eat because I felt so clean inside I didn’t want to pollute myself. That’s an amazing feeling. Ketosis can do a lot of stuff in addition to the metabolic effects.