Advertisement

Low-carb diets take advantage of the body's ability to burn fat and feel less hungry when in a state called ketosis. While many people try these diets, they are particularly beneficial to those with type 2 diabetes, metabolic syndrome, and insulin resistance. Even if a person with these health concerns is not trying to lose weight, they might benefit from a doctor-recommended keto diet.

For this diet to work properly, you need to be in a state of ketosis, where the body burns fat as fuel because it does not have access to enough carbohydrates. While some people rely on urine testing strips to determine if they are in ketosis, there are several signs and symptoms — essentially the side effects of this bodily state — to look for as well.

Advertisement

Bad Breath

Bad breath is probably the complaint that most people hear about when talking about ketosis. Elevated ketone levels are responsible for the fruity smell that develops on the breath of people in ketosis. The same process can also give the urine a distinctive odor.

Fortunately, the bad breath that comes along with a ketogenic diet isn't an indication that anything is wrong; in fact, it means your body is responding to the diet.

young man smelling his breath against his hand
Advertisement

Loss of Appetite

If you are hoping for weight loss, this is a welcome symptom that your body is in ketosis. Researchers aren't sure exactly why reduced appetite comes along with ketosis. They think perhaps the ketones provide signals to the brain, reducing hunger. The high levels of protein and vegetables required for a ketogenic diet may also help regulate hormones that signal hunger.

woman refusing plate of pancakes being offered
Advertisement

Fatigue

Also known as keto flu, it can be difficult to push through symptom this unless you understand it is temporary. The body needs some time to adjust to this new way of eating and learn how to fuel itself without carbs. It makes sense to experience fatigue during this time.

Adding electrolytes or even just potassium and magnesium to the diet can help make this adjustment period easier to push through.

man fallen asleep at his desk at work
Advertisement

Improved Energy and Concentration

If they tough it out through the initial stage of keto flu, many people are rewarded with an improvement in overall energy levels, as well as an increased ability to focus. Once the brain switches from using glucose to ketones for fuel, energy and clarity get a boost. Ketones are an easy-to-use and powerful source of fuel for the brain, so it makes sense that once the brain becomes adept at using ketones rather than glucose, these benefits appear.

woman focusing on notebook and laptop screen
Advertisement

Increased Thirst

People new to ketosis should expect to be thirstier than they used to be. In addition to some early water weight loss from a ketogenic diet, elevated ketone levels can also cause dehydration. Offset this concern by setting reminders to drink water frequently and supplement with electrolytes. Always keep an eye on other indicators — for example, if the urine remains too dark despite drinking a good amount of water, see a healthcare provider.

woman drinking a glass of water
Advertisement

Upset Stomach

The switch to a ketogenic diet is a big change for most people eating the standard American diet. It makes sense that the shift can lead to an upset stomach. To avoid this as much as possible, people on the diet should stay hydrated and make sure they are eating enough fiber to minimize discomfort. Some people find relief by taking probiotics. The good news is, the body will adjust to this way of eating after the initial learning phase.

young man holding his stomach, in pain
Advertisement

Sleep Issues

During the first few days of sticking to a ketogenic diet, many people find themselves tossing and turning during the night or waking up in the early morning hours and struggling to fall back asleep. This has less to do with the high levels of ketones and more to do with lower carb levels. Just like carbs make us drowsy after a big meal, they help us sleep at night. Like other symptoms of ketosis, the body should adjust to the change.

woman awake at 3:41 am, insomnia concept
Advertisement

Headaches

While headaches can occur alongside the keto flu, developing headaches without other symptoms is common as well. There are a few reasons why headaches are common with ketosis, including the reduction of sugar in the diet and dehydration Many people also cut back on caffeine by reducing soft drink or coffee consumption when making these dietary changes, so headaches for the first little while are to be expected. If they continue longer or become overwhelming, see a doctor.

older man with headache pinching his nose
Advertisement

Weight Loss

The side effect that many people look forward to when eating a ketogenic diet is weight loss. For a long time, it was thought that calories were calories and any weight loss was the result of eating fewer calories. Now researchers are finding that ketogenic diets provide better weight loss results than low fat and low-calorie options.

woman standing on bathroom scale
Advertisement

No Symptoms

Some people experience few, if any, side effects of going on the ketogenic diet. That's great, and they are lucky, but how can they be sure they are in ketosis without experiencing symptoms? Urine test strips are very accurate for determining whether ketosis has kicked in. There are also monitors that use the breath, but these are generally considered less reliable.

Testing the urine isn't strictly necessary, though. It is generally accepted that people who limit their carbohydrate intake to 50 grams or less and eat 1.5 grams of protein for each kilogram of body weight will go into ketosis. Anyone who was instructed to begin the ketogenic diet but thinks they are not going into ketosis should talk to their doctor.

smiling woman holding bowl of cauliflower and broccoli

Disclaimer

This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.