Whether you're just starting out or have been keto dieting for years, broken-down fat, or ketones, keep your body up and running 24 hours a day. There are three stages of ketosis: beginner, cyclic, and fat-adapted. No matter where you are in your low-carb journey, rotating in and out of these stages happens. Ketone levels will vary depending which stage you're in, and natural factors, whether it be catching a cold or consuming too much sugar, can cause ideal numbers to rise and fall. While the choice is entirely up to you, many dieters monitor ketone levels to find out if they've reached ketosis, maintained it healthily, or achieved the optimal numbers for their unique goals. Since interpreting those numbers can be difficult, and since ketone levels vary throughout the different stages, here's a basic rundown on what to expect.
Stage 1: Beginning
When you first begin a ketogenic diet, your goal is to maintain nutritional ketosis for as long as you can, consistently burning ketones for fuel. If you've swayed away from the diet for awhile, whether your goals changed, life got in the way, or you had a lengthy, carb-heavy vacation, you might start back at the beginning stage as your body readjusts to running on ketones, using up its fat stores for fuel. If you eat a lot of carbs, your body will not achieve, much less stay in, ketosis. At this stage, monitoring your macros and sustaining a keto-friendly meal plan is crucial.
Whether you aim to do keto short or long-term, whether you aim to lose weight or improve your mood, this is the stage where your body is settling into ketosis for the first time (or the hundredth time). It's learning to run on ketones, using up fat stores for fuel. For most people, getting into ketosis takes about 2 to 3 weeks. If you're brand new to the diet or are starting up again, try to stick with your macros as closely as possible. At this stage, small changes can make a difference in your numbers, so watch out for that extra piece of fruit. It might not seem a big deal, but at this stage, especially for first-timers, it does make a difference.
Readings for Stage 1
At the beginning stage, you'll achieve ketosis at 0.5 mmol/l, or 80 mg/dls of blood glucose. Most beginners know they've reached ketosis once they stop feeling the constant hunger pangs and blood sugar ups and downs that a traditional, carb-heavy diet naturally causes. If you're feeling happy and healthy without eating for extensive periods of time, you're more than likely burning fat for fuel, and have achieved light, nutritional ketosis. Ketosis is all about how you feel, so if you're feeling happy, healthy, and well-adjusted, that matters more than the numbers.
Stage 2: Keto-Adaptation
The cyclic, or keto-adaption stage, happens once your body has successfully adjusted to a state of nutritional ketosis, and is burning ketones for fuel on a regular basis. While the first stage is aimed at getting into ketosis, the second stage is aimed at becoming keto-adapted, maximizing your fat-burning abilities. The better you are at burning fat, the higher your reading, but this also depends on your unique goals and overall health. When you're keto-adapted, you're enjoying a low-carb, moderate protein, high-fat diet regularly, and your body is routinely using ketones for fuel. This is the stage where you start adjusting to the low-carb lifestyle and making it a key component of your day-to-day function.
During this stage, it's pertinent to stick with a low-intensity workout routine, as high-intensity exercise (examples include weight-lifting, sprinting, and sports) can quickly deplete your muscle glycogen, kicking you out of ketosis and dropping your reading. Once you've become keto-adapted, you'll be able to switch back to high-intensity exercise, but for now, stick with light walking, yoga, and other low-intensity activities that burn calories without burning away muscle glycogen.
If you want to become keto-adapted and maintain ketosis regularly, this is crucial. Becoming fully keto-adapted will take several months. Once you're fully adapted, however, if your body jumps out of ketosis during a cheat day, you'll bounce back quickly. While maintaining 24/7 ketosis is ideal, it isn't necessary to sustain keto-adaptation. As long as you're maintaining your diet the majority of the time, an extra apple here or there isn't going to harm your body, and at this stage, dieting itself should be rather easy. What do readings look like once you've finally adapted to keto?
Readings for Stage 2
As you adjust, this reading can range from 0.5 mmol/l to 1.5 mmol/l, and your body should be staying within this level, using fat for fuel regularly. During the cyclic stage, your body is adapting to using fat and ketones as its main source of energy, so this reading can shift somewhat. It should, however, remain within this range. At this stage, using Ketostix for monitoring can reveal which reading makes you feel the best and keeps you well within the range of mild ketosis.
Stage 3: Fat Adaptation
This is the final stage, the goal that every keto dieter wants to reach. This means that your body has achieved full fat-adaptation, and will be running successfully with ketones as its fuel force 24 hours a day—even as you sleep. At this stage, your body will notice if you go off base a little. Let's say you've been fully keto-adapted for six months, and then indulge on a week-long, carb-filled cruise. Your body will quickly notice the difference, and you're going to feel sick, fragile, and light-headed. Even if you accidentally indulge on gluten one day, your body will notably feel those changes, and it could cause your ketone levels to crash.
Ideally, you won't be eating those foods in the first place. Since some opportunities are impossible to ignore, however (Italian vacation, I'm talking to you), your body will know the difference. It's used to running on fats, and throwing carbs back into the mix is going to result in an uneasy feeling until you readjust, which depends on how long you've been fully fat-adapted and how long you indulged. Recovering from a cheat day after just one bad meal, for instance, is still easy to do in a day. Recovering from a week's worth of bad meals could take a week, but if you've been keto dieting for years, you could still bounce back quickly. This is where monitoring ketone levels makes a difference. When you know your ideal numbers, you know what works and what feels best for you on a normal day.
Readings for Stage 3
At stage 3, you have officially reached optimal ketosis. Congrats! This is difficult to do, and not every keto dieter reaches this stage. Once your body learns to run on fat for fuel, you naturally burn more fat, maximizing workouts and weight loss. Here, the ideal reading is always 1.5 mmol/l to 3 mmol/l. If you're going keto for therapeutic reasons, however, your level should be higher, so always speak with your doctor about ideal ketone levels for your condition. Otherwise, keep in mind that once you're fully fat-adapted, numbers can plummet due to workouts and off-days, but they will bounce back. Low readings are actually quite common for fat-adapted dieters, as they show that your body is burning fat so quickly, it's hard for those Ketostix numbers to catch up. Try again in an hour, and you might get a higher reading. Again, knowing which level feels best for you is key.