Being in ketosis is not just important for weight loss; it also plays a crucial role in addressing various health issues, inflammatory conditions, and metabolic problems. However, testing for ketones isn’t always reliable.

Urine and breath analyzer tests may initially indicate ketosis, but as your body becomes more efficient at using ketones, these excess ketones no longer show up in tests. Blood tests are more accurate, but they can be expensive and slightly inconvenient due to the need for pricking your finger. Fortunately, there are nine key signs that can indicate whether you’re in ketosis or not.

1. Keto Flu, Fatigue, and Rash

The first sign is actually a set of symptoms that commonly occur during the transition into ketosis. Typically, it takes two to three days to enter ketosis, depending on how low your carbohydrate intake is. If you’re not supplementing with enough B vitamins, electrolytes, and sea salt, you may experience:

• Keto Flu – Symptoms like headaches, dizziness, and nausea due to electrolyte imbalances.
• Keto Fatigue – Feeling drained as your body adapts to burning fat instead of glucose.
• Keto Rash – Skin irritation that some people experience due to changes in metabolism.

These issues are far less likely if you follow a well-balanced, nutrient-dense ketogenic diet rather than a “dirty keto” approach, which focuses only on low-carb intake without prioritizing food quality. Additionally, if you experience diarrhea, it could be due to consuming large amounts of vegetables, as your body may not yet have the right gut microbes to process that much fiber.

2. Rapid Weight Loss

A clear indication of ketosis is weight loss. Initially, you may lose anywhere from 7 to 14 pounds within the first one to two weeks. This is mostly water weight. When you consume carbohydrates, your body stores glycogen along with water—approximately 3 grams of water per gram of glycogen. As you reduce carbs, your body releases this stored water, causing rapid initial weight loss. After the first couple of weeks, weight loss slows to 1-2 pounds per week, which is normal fat loss rather than water loss. If you incorporate intermittent fasting, fat loss can accelerate even further.

3. Looser Clothes Around the Midsection

One of the first areas where you’ll notice fat loss is your midsection. When in ketosis, the liver starts breaking down fat, which reduces fatty liver and visceral fat—the deep fat surrounding your organs. This is a great sign that ketosis is working because it signifies that you’re improving insulin sensitivity and reducing harmful fat accumulation.

4. Increased Energy Levels

One of the biggest benefits of ketosis is higher energy levels. Fat is a more efficient energy source than glucose, providing 9 calories per gram compared to 4 calories per gram for carbs. Once you switch to fat as your primary fuel, you experience stable, long-lasting energy without the crashes associated with carb-based diets. You’ll also feel less dependent on frequent meals to maintain energy.

5. Improved Cognitive Function

Ketones are excellent for brain health. If you notice enhanced focus, memory, and attention, it’s a strong indication that you’re in ketosis. Ketones can bypass the damage caused by insulin resistance in the brain, helping neurons function more effectively. This is why ketogenic diets have been linked to improved cognitive function and even potential benefits for neurodegenerative diseases.

6. Reduced Inflammation and Pain

Ketones act as natural anti-inflammatory molecules. Many people experience relief from inflammatory conditions such as arthritis and autoimmune disorders when following a ketogenic diet. If you notice a significant reduction in pain and inflammation, it’s a good sign that ketosis is working in your body.

7. Feeling More Satisfied After Eating

A major benefit of ketosis is improved nutrient absorption, which helps you feel more satisfied after meals. When your body is insulin-resistant, it struggles to absorb essential amino acids and nutrients. As ketosis reverses insulin resistance, your cells become better at utilizing nutrients, making you feel fuller for longer and reducing unnecessary cravings.

8. Improved Mood and Reduced Anxiety

If you experience fewer mood swings, reduced anxiety, and an overall improved sense of well-being, ketosis may be playing a role. Brain insulin resistance can contribute to depression and anxiety, and by improving insulin function, the ketogenic diet helps balance neurotransmitters. Multiple studies have linked keto with mood improvements, although results can vary depending on the study design.

9. Reduced Appetite

Perhaps the best indicator that you’re in ketosis is the dramatic decrease in appetite. When your body efficiently burns fat for fuel, it no longer depends on constant carbohydrate intake. This allows you to go longer periods without eating and feel naturally less hungry, making it easier to stick to the diet long-term.

Recognizing these signs can help you confirm whether you’re in ketosis without the need for expensive testing. If you want to optimize your ketogenic journey, the next step is understanding the best version of keto to follow. To learn more about how to start keto properly, check out this guide on the healthiest way to approach a ketogenic diet.