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The ketogenic or simply keto diet is a low-carb, high-fat and moderate-protein diet.

It affords many health benefits, including weight loss, blood sugar control and longevity (1, 2, 3).

A common goal of people on the keto diet is to achieve ketosis, a natural state in which your body burns fat for fuel.

However, it can be difficult to determine whether your diet needs adjusting to reach and maintain ketosis.

For this reason, many people use keto strips.

This article explains how to use keto strips to measure ketosis and how to reach this state through a ketogenic diet.

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What happens during ketosis?

If you follow a standard high-carb diet, your cells use glucose as their main energy source, which comes from the carbs in your diet, including sugars and starchy foods like bread, pasta and vegetables.

But if you limit or avoid these foods — such as when you’re on a keto diet — your body doesn’t have enough glucose to meet its energy needs. This means it must look for alternative fuel sources.

Your body does this by breaking down stored fat into fatty acids and ketones. These ketones replace glucose and supply most of the energy your brain needs, resulting in a physiological state called dietary ketosis (4).

Being in dietary ketosis increases your ketone levels, which are detectable in your breath, urine and blood (5).

When you restrict or limit carbs from your diet, your body produces ketones from fat, resulting in the physiological state of ketosis.

Measuring ketosis using urine

If you want to know if you’re in ketosis, urine strips are a cheap and convenient way of finding out.

They were originally developed for people with type 1 diabetes to determine if they’re at immediate risk for diabetic ketoacidosis, a potentially life-threatening condition (6).

You can purchase urine strip kits over-the-counter at your local pharmacy and supermarket, as well as online. They’re relatively inexpensive and can contain from 50 to several hundred strips.

The strips typically expire within three to six months after opening, so keep in mind how often you intend to use them (7).

If you want to check your urine ketones day-to-day, stick with a specific time, like in the morning or several hours after your last meal of the day, for best comparison (8).

The process of using keto strips looks like this:

• Wash your hands, then take a urine sample in a small container.
• Immerse the absorptive end of the strip into the sample for a few seconds, then remove.
• Wait for the amount of time outlined on the package for the strip to change color.
• Compare the strip with the color chart on the packaging.
• Dispose of the urine and strip in an appropriate manner before washing your hands.

The color corresponds to the concentration of ketones in your urine, which can range from no ketones to high concentrations. The darker the color, the higher your ketone levels.

Urine strips are an easy and convenient way to measure ketosis. Follow the directions on the kit for the most accurate results.

Measuring ketosis with blood

Ketone blood meters are a reliable and accurate way to measure the ketones in your body (9, 10, 11).

Originally designed for people with type 1 diabetes, they also appeal to those following a ketogenic diet as a more accurate way to measure ketosis (7).

You can usually find blood strips at any place that carries urine strips. However, you will need a meter to read the blood strips as well.

Many blood glucose readers will also read blood keto strips, even though the glucose strips are different from the keto strips.

Blood strips cost on average $1 per strip and typically last 12–18 months before they expire — much longer than urine strips (7, 12).

Here’s how a blood ketone meter works:

• Wash your hands.
• Load the lancet with the needle, following the directions provided.
• Insert a blood ketone strip into the ketone meter.
• Prick your finger to draw a small drop of blood using the lancet.
• Let the strip come in contact with the drop of blood and check the results.
• Dispose of the strip and lancet as suggested in the directions.

A preferable blood level of ketones for dietary ketosis is 0.5 – 3 mmol/L (9 – 54 mcg/dl) (11).

Measuring the ketones in your blood is a more accurate but also more expensive way of measuring ketosis.

How accurate are keto strips?

Urine strips are a good tool to measure whether you’re in ketosis during the first few weeks of going keto.

During this time, your body can’t use ketones efficiently for energy, and so you urinate many of them out (13).

But as you get deeper into ketosis, your body adapts to using ketones for fuel and becomes more optimized in producing them, leaving less unused (14).

In other words, if you’ve been in a keto-adapted state for many months, a keto strip may indicate that your urine contains only trace amounts of ketones, if any. This can mislead people into thinking they’re no longer in ketosis, which may not be the case (14).

Nonetheless, using urine strips when you’re just starting a keto diet is an easy and affordable way to see if your ketone levels are rising.

On the other hand, if you’ve followed a ketogenic diet for several months and want a more accurate picture of your ketone levels, blood keto strips are a more suitable option (11).

However, it’s important to consider the higher price of the blood strips and whether you want to prick your finger every time you measure your ketone levels.

Urine keto strips can help you determine if you’re in ketosis, but possibly not on the long run. If you want a more accurate reading, blood keto strips are a better option.

How to get into ketosis with a keto diet

For healthy individuals, it can take several days on a keto diet to go into ketosis and a few more weeks thereafter to become keto-adapted (5).

A keto diet is high in fat, moderate in protein and very low in carbs.

Some people mistake the keto diet for being low in carbs and high in protein. But consuming too much protein will not allow your body to enter ketosis (15).

More specifically, the diet allows 65-90% of calories from fat, 10-30% from protein and less than 5% from carbs.

For comparison, the 2020-2025 Dietary Guidelines for Americans recommends that people get (16):

• 20–35% of calories from fat
• 10–35% of calories from protein
• 45–65% of calories from carbohydrates

Usually, consuming less than 50 grams of carbs per day will get you into ketosis. That being said, everyone is different — some people may need to eat less while others can get away with more (5).

If you’re new to the keto diet and want to make sure your diet is on track, urine strips can be a useful tool.

A keto diet is a high-fat, low-carb and moderate-protein diet. It takes several days for your body to enter ketosis and several weeks thereafter to adapt to using ketones for fuel.

The bottom line

Ketone strips have become increasingly popular as a way for people following a keto diet to check whether they’re in ketosis.

There are two types of keto strips: urine and blood.

Urine strips are ideal if you’re new to the keto diet and want an easy and affordable way to ensure you’re headed towards ketosis.

Once your body has become keto-adapted, blood strips are more accurate but also more expensive.

In either case, the strips can help you monitor and adjust your diet accordingly to get into and maintain a level of ketosis.