Latest / Common Sense Health / The Midnight Ketone Mystery: Why Your Best Fat-Burning Happens While You Sleep
Transcript
- Stephen Thomas BSc. Hons: Hello. Have you ever checked your ketones first thing in the morning? Seen 0.2 on the screen and thought, hang on, I'm eating hardly any carbohydrate. Where have all my ketones gone? Now, before you start interrogating your breakfast, there is something worth considering. You might simply be measuring at the wrong time to see your highest reading. One of the interesting things about continuous ketone monitors is they let us see what happens between those fingerprick tests. Now previously most people checking blood ketones at home were taking individual snapshots. Useful snapshots, certainly, but you could miss quite a lot of the story. When I tried a continuous ketone monitor myself, I noticed that my ketones sometimes rose considerably overnight and came down again around the time I would normally have checked them with a finger prick. So that low morning reading wasn't necessarily telling me what I'd been having happen to my body while I was asleep. And this isn't just something I've noticed in my own readings. A female client has kindly shared these results along with what she was eating. I'm keeping her anonymous, but her charts are a useful illustration of why timing matters. When we look at image one, we can see her ketones over a 24-hour period. She was eating one meal a day between half past one and half past two in the afternoon, and the meal was reported. seven ounces of sable fish, six rashes of bacon, three ounces of chuck steak, and three ounces of butter. There was no structured exercise involved, just the normal walking that comes with everyday activities. Now look at that blue line. Her lowest recorded keto level was 0.8 millimoles per litre at 7.19 in the evening. Later on There are two quite noticeable rises, with the highest reading reaching five point four millimoles per litre at 534 in the morning. And after that final peak, the line comes down quite sharply. Now that is an important observation here. A test taken during the evening, one taken at half past five in the morning, and another taken after waking could give you three very different impressions of the same person's ketone levels. She also reported a waking fingerprint. Ketone reading of 4.6 on her keto mojo with glucose at 80 milligrams per deciliter. Now that glucose works out at approximately 4.4 millimoles per liter. Her continuous monitor was showing 3.8 for ketones. Now those readings weren't identical, and we shouldn't expect the two methods always to match perfectly. A fingerprick meter measure is from capillary blood, whereas the continuous sensor measures the fluid between the cells. There can be a delay between those compartments, particularly when levels are changing, as well as measurement differences between devices. You'll also notice that the app says she was burning fat at around 23.98 grams an hour. Now, I would be very cautious with that claim. The sensor is measuring ketone concentration. It isn't directly measuring grams of fat being burnt, and it certainly isn't establishing how much body fat she is losing. That number is an algorithm generated estimate rather than a measured fat burning rate. The trace is interesting enough without asking it to tell us something it cannot directly measure. So why do ketones generally rise with a ketogenic or carnivore way of eating? I know the name ketogenic does imply that would be obvious, but when carbohydrate intake is sufficiently low, insulin levels tend to fall, and the liver becomes more active in producing ketones from fatty acids. So those fatty acids can come from the food you've eaten or from your own stored fat. That distinction matters because a higher ketone reading doesn't automatically mean more body fat is being lost. The liver turns some of that fatty acid supply into ketones, which can then provide fuel for tissues, including the brain, the heart, and obviously the muscles. And with one meal in the early afternoon, there is also a long stretch without food before the following morning. That extended fasting window can favor. Ketone production. But we need to be careful about explaining the exact overnight shape. These charts don't measure insulin or growth hormone or cortisol or ketone uptake. So that can tell us not as much as we like, really. There's no precise mechanism that we can attribute to each rise or fall. Meal timing, the composition of the meal, the length of the fast overnight, hormonal changes and changes in fuel use. Could all contribute. So some people also see a morning glucose rise as the liver helps prepare the body for waking up. And that can affect the balance between glucose and ketones, but it doesn't produce an identical response in everybody. You know, in other words, an overnight rise is something we can observe here, but it isn't a rule that everyone's ketones must follow. Now, when we look at image number two, we can see another 24-hour trace from the same client. For this one she reported seven ounces of chuck steak, one egg, five rashes of bacon and two ounces of butter. Now again, look at the movement rather than just the number at the end. Her ketones reached a low of 0.4 millimoles per litre at 6.39 in the evening. Then they rose overnight, reaching 3.9 millimoles per litre at 3.04 in the morning before falling again towards the morning. By the end of the trace, they were around 1.7, 1.8. Imagine if she'd only tested in the evening. And she might have seen 0.4 and wondered whether she was producing many ketones at all. Yet a few hours later, the continuous monitor recorded a substantially higher concentration. The app says that she spent 85% of that recording period between 0.5 and 3 millimoles per litre. In image one, the figure was 82%. So those percentages describe time within the app selected range. They aren't a score for metabolic health and there is no need to chase a higher peak simply to make the graph more impressive. And again, the 9.82 grams an hour figure in the image should be treated again as an estimate, not a direct measurement of fat oxidation. This is where it helps to have glucose readings alongside ketones. When we look at image three, we're looking at results from a different woman who took part in my fasting reset. I converted her glucose readings from milligrams per deciliter into millimole per liter by divided by 18 basically. So glucose and ketones could be displayed using the same units. And that makes the pattern easier to see. Although sharing the same units doesn't mean the two substances provide equivalent amounts of energy, by the way. The glucose readings began at about six point one on Sunday, then moved to approximately four point nine on Tuesday, five point three, and then four point eight. In the two Wednesday readings and 3.6 on Thursday. So glucose falls overall, but it doesn't come down in a perfectly straight line. The ketone readings rise from approximately 0.2 on Monday to 1.1 on Tuesday, around 1.3 on Wednesday, and about 4 on Thursday. To me, it looks like the faders on a mixing desk as the glucose fader comes down overall, the ketone fader comes up. And that is a useful picture of the change in fuel environment during fasting. But these are separate readings across several days rather than a continuous reading, and they don't establish a fixed one-for-one relationship between glucose and ketones. I mean, the body still needs some glucose, and the liver continues making it even when we aren't eating carbohydrate. There is another important point running through all three images. We're looking at ketone concentration, not directly at ketone usage. So with the finger prick results, that is ketones in the blood. With a continuous monitor, it is ketones in the interstitial fluid. Think of it as the amount of fuel waiting in circulation. That amount depends on how quickly ketones enter the system and how quickly they are taken up or used or otherwise cleared. A higher reading could reflect greater production or reduced clearance or a combination of both those things. A lower reading could reflect less production, but greater uptake, or both. You cannot look at a low number. And confidently say, I'm using them brilliantly. Equally, you cannot look at a high number and confidently say, I'm burning more fat. Now, I've also tried the Lumen device because I was interested in looking at fuel use from another angle. The underlying idea relates to respiratory quotient, the amount of carbon dioxide produced relative to the amount of oxygen consumed as we metabolize fuel. In simple terms, Carbohydrate and fat have different chemical structures. So burning them produces different relationships between oxygen use and carbon dioxide production. For carbohydrate, the ratio is around one, and for fat, it is around 0.7. In a laboratory, measuring both gases in your breath can help estimate the mixture of fuels you're oxidizing. Technically, the ratio measured at your mouth is called the RQ or the R E R. The respiratory exchange ratio, and it best reflects what is happening in the tissues under sort of steady conditions. Now, the lumen doesn't directly measure that full ratio because it doesn't measure oxygen consumption, it measures exhaled carbon dioxide and uses a standardized breathing maneuver and an algorithm to estimate whether your fuel use is leaning more towards fat or more towards carbohydrate. And that makes it an interesting additional tool, but it has its limitations. Breathing technique, recent activity, and whether you are resting under consistent conditions can influence the result. Its estimates also shouldn't be treated as interchangeable with a laboratory metabolic assessment, particularly during prolonged fasting or marked ketosis. Crucially, it doesn't tell you specifically how many ketones you are using, nor does a fat burning result distinguish dietary fat from stored body fat. So we have different tools giving us different pieces of information. And none of them gives us the whole picture on its own. And a quick safety point: high ketones need a different interpretation in someone with diabetes, particularly someone taking an SGLT2 medicine or anyone feeling unwell. Ketoacidosis can sometimes occur without very high glucose. if you've got nausea or vomiting, abdominal pain, or unusual rapid breathing alongside raised ketones. That warrants urgent medical assessment. That's very rare, but worth putting into this video. Now, for someone otherwise well when following a ketogenic or carnival way of eating, the useful message here is that context and timing matter. A single morning ketone reading cannot tell you what happened throughout the night, how much fat you burnt, or how effectively your tissues have used those ketones. These monitors give us a much more interesting view of the ups and downs. So before a reading of zero point two ruins your morning, remember you may have missed the overnight performance. Your ketones don't necessarily keep normal office hours. And this video is in response to so many people that do use a fingerpricking device for the ketones and worry. It's only zero point two, it's only zero point four. Yeah, I genuinely think, and certainly from my readings, I was so surprised to see how high my ketones were overnight. So If you're not measuring at three o'clock in the morning or two thirty in the morning or four o'clock in the morning, that might be what you're actually missing. But I'm not recommending you disturb your sleep to prove yourself right or wrong. But I do think there's some utility in the continuous ketone monitors, and it's certainly opened my eyes up to the very big range of flexibility in the ketone readings throughout a 24-hour period. Anyway, hope you enjoyed that. If you did, please like and share. And subscribe and dropping a comment would be really helpful. And have you tried a continual ketone monitor? Was it successful? Was it reliable? Did you find anything different that you expected? Anyway, I'd love to hear from you. Cheers. I'll be back.