How to tell if you're in ketosis, from monitoring your bathroom patterns to testing your blood

ShutterstockThe keto diet.
  • Ketosis is a state in which your body uses fat, rather than carbs, for fuel.
  • It’s not always obvious if you’re in ketosis or not, but some symptoms can indicate that you are.
  • Certain tests can give you a better idea if you’re in ketosis.
  • Visit INSIDER’s homepage for more stories.

The whole point of the keto diet is to achieve ketosis, or that glorified mode in which your body burns fat, rather than carbs, for energy. But if you think you’re in ketosis when you’re not, or think you’re not when you are, you can come up short on your goals.

Fortunately for people determined to follow the plan (which, by the way, many health experts don’t recommend), there are some signals that can indicate you’ve entered ketosis. There are also tools you can use to determine if you’re in ketosis or not.

Here, registered dietitians explain what to look out for if your goal is ketosis.

You have bad breath

During ketosis, you’ll pee out ketones, or chemicals your liver makes from fat to fuel your muscles and other tissues, according to WebMD. You can also smell ketones on your breath, said registered dietitian Penny Scholl, who’s maintained a 120-pound weight loss on a low-carb plan.

Scholl said your breath may take on a noticeable fruity smell, while other people say it makes their breath smell like nail polish remover.

You need to go to the bathroom more

When you begin restricting carbs, your kidneys switch from retaining salt to excreting it, Scholl said. When this occurs, people notice that they take more frequent trips to the bathroom to pee.

Read more:
10 of the biggest downsides of the keto diet

You don’t have a lot of energy

The body does not immediately switch from using glucose to ketones for fuel, Scholl explained. As you transition, you’ll likely feel sluggish.

You feel like you have the flu

The “keto flu” describes symptoms including headaches, irritability, difficulty sleeping, and weakness, Scholl said. Part of this is due to the body switching over to a new energy source, she explained, and some of it is due to the loss of sodium and other electrolytes due to frequent urination.

Often, these symptoms can be reduced by staying hydrated and replacing electrolytes by adding a bit of salt to your food, she said. The symptoms should also decline with time, said Ohio-based registered dietitian with Abbott Pam Nisevich Bede. “Research shows that most people can achieve ketosis in less than a week after implementing dietary changes, but a full adjustment to the keto diet usually takes three to five weeks, if strictly adhered,” she said.

You’re not very hungry

Many people find that they are not as hungry on the keto diet as they used to be, Scholl said. “This is thought to be due to the suppression of hunger-related hormones such as ghrelin,” which stimulates appetite, she explained.

You’re constipated

“Cutting out vital fibre sources from grains and fruits can disturb digestion and the microbiome in your body,” said Miami-based registered dietitian MonicaAuslander Moreno. One result is constipation, though you can also experience vitamin and mineral deficiencies and possibly put yourself at risk for certain diseases.

You have trouble sleeping

“Ketosis can cause disturbed sleep” because the body is physically in a state of starvation, which messes with sleep, Auslander Moreno said. Without many carbs, too, the body can experience dips in certain sleep-promoting hormones, though long-term, the keto diet may improve sleep, according to an earlier INSIDER story.

A keto stick (or blood glucose meter or breathalyzer) tells you you’re in ketosis

“One of the best ways to determine if you are in ketosis is by using keto sticks,” Scholl said. There’s usually a colour key included on the bottle of keto sticks, which will show you the level of ketones in your urine. If you are excreting ketones, then you are probably in ketosis.

For an even more accurate test, ask your doctor to take a blood sample to test serum blood ketones, suggested New York City-based registered dietitian Abigail Rapaport. Alternatively, you can purchase a blood glucose meter specifically designed to test ketones. However, keep in mind that these tests are more invasive than urine sticks, since you need to prick your finger, Rapaport said.

A breathalyzer that monitors acetone, a byproduct of ketosis, is another option to consider, Rapaport said. Still, breathalyzers may not be as accurate as blood ketone meters and they tend to be more expensive than ketone urine strips, she said.

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