Am I in Ketosis? How to Know if Your Ketogenic Diet is Working

The ketogenic diet is gaining momentum as a way to help you shed unwanted weight, improve cognitive function, and even gain or maintain muscle mass. So many people report busting cravings and gaining energy when they cut carbs and add more healthy fat to their diet. But how do you know if you’re in ketosis? Do you have to test? Are the physical benefits enough? Read on to find out.

In this article, you will learn:

How to Measure Ketone Levels

Ketones are molecules your body produces as an energy source once you cut out most carbs and replace them with healthy fats. The ketogenic diet is different than other “low-carb” diets because there are specific measurements of blood ketones that signify when you’re in fat-burning ketosis.

If and when you’re ready to test, look for ketone levels above 0.3 mmol/L. If you’re at or above this number, you’re technically in ketosis; although many experts consider optimum ketosis to be between 0.5 and 3.0 mmol/L. 

When to Test Ketone Levels

The amount of time it takes to get into ketosis varies from person to person. For most people who stay at or under their net limit, it can take anywhere from 2-7 days to get into ketosis. For others, it can take longer.

Knowing this, you can start testing your ketone levels after 2-3 days, or you can wait up to 1-2 weeks after sticking to a strict keto diet. At this point, it’s more likely that you’ll be done with any keto flu symptoms and your glycogen stores will be depleted, so you won’t waste your time or ketone testing strips.

Another option is to track your ketone levels at the same times every day for the first several weeks, along with your energy levels, digestion, bowel movements, and other symptoms.

3 Tools for Testing Ketone Levels

Ketone Monitor

The most accurate way to test your ketone levels is with a blood test. Most blood tests work like blood sugar monitors with a tiny pinprick to the finger, followed by placing a drop of blood on a test strip. The test strip measures the amount of BHB (the main ketone your body produces) in your bloodstream.

The pros are that you’ll get a really accurate, real-time reading of your ketone and blood sugar levels. The cons are that these strips can get a little pricey - about $1.30 per strip. This can add up if you’re testing multiple times per day.

Urine Testing Strips

Urine ketone testing strips are easy, painless, and less expensive than blood strips, but they’re also less accurate than blood.

When you’re first getting into ketosis, your body will excrete excess ketones into your urine. That’s why urine strips are an “ok” testing route to take when you’re first starting out on the keto diet.

Over time, however, your body will adapt, producing and using ketones more resourcefully and excreting way fewer ketones in the urine. That means your blood levels could still be high, but your urine levels won’t reflect that.

Breath Testing Strips

Also less accurate than a blood ketone reader, a breath ketone meter will test your ketone levels via the amount of acetone (another ketone body) in your breath. The pro is that you don’t need to replace the strips, so this can be a more affordable testing option over time.

The cons are accuracy. These seem to test well for lower ketone levels, but there’s not enough formal data to confirm their accuracy when it comes to higher ketone levels. 

Other Ways to Determine if You’re in Ketosis

Rapid Water Loss

Yes, you will likely lose fat on the keto diet. Especially if you have a lot of unwanted fat to lose. But the weight you lose in the first couple of weeks on the keto diet is more likely water weight than fat. As your body burns through stored glycogen, it’s also releasing a lot of stored water (glycogen is made of mostly water).

So, if you’re experiencing more trips to the bathroom than usual – that’s normal. You can expect this frequent urination to subside after your glucose stores are depleted and you’re more fat adapted.

Long-Term Weight Loss

It’s also important to note that while most of the weight you’ll likely lose in the first week or so is because of water loss, there’s some strong evidence for long-term weight loss on the ketogenic diet.

Appetite suppression on the keto diet results in eating fewer calories overall, which is the best explanation as to why so many people lose so much weight on the keto diet.

However, research also suggests that gaining and maintaining muscle mass on the keto diet is easy to do; even in a calorie-restricted state! So, if you’re keeping your protein levels to about 1-1.6 grams per kilogram of body weight and working out regularly, don’t be surprised if the numbers on your scale don’t drop dramatically. You could be gaining muscle mass as you lose fat.

Replace your daily weigh-in with a tape measure! Measuring the circumference of your waist, hips, thighs, chest, and upper arms will give you a much more accurate picture of how your weight is being lost, gained, and redistributed.

Symptom Journal

Some people can tell if they’re in ketosis because of their physical symptoms. If you’re not ready to invest in testing strips or a breath meter, you may want to track how you’re feeling during those first few weeks on a keto diet. If you’re experiencing several of the following symptoms during the first few weeks of your keto diet, it’s very likely you’re in ketosis.

Signs and Symptoms of Ketosis

Symptoms common to getting into ketosis, but usually subside within a couple of weeks:
  • Bad breath
  • Insomnia
  • Short-term fatigue or keto flu
  • Frequent urination
  • Changes in digestion
Some common side effects after you’ve been in ketosis for a few weeks:
  • Lasting weight loss
  • Suppressed appetite
  • Better digestion
  • Steady energy throughout the day
  • Better, deeper sleep
  • Sharper cognitive function

While the most accurate way to know if you’re in ketosis is blood or urine strips, there are other ways to measure your progress. And remember, if you’re not feeling well during those first few weeks, not to worry! It’s likely you’re just experiencing the temporary symptoms of the keto flu.

Check out this article for all the details on the keto flu and how to kick it fast.

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