Veggie Blog

Atkins and ketosis

What is ketosis?

The core idea of the Atkins diet is that a state called ketosis makes your body burn its fat stores for energy. Many people, even some who follow low-carbohydrate diets, are not sure what ketosis is or why it works, so here is a plain explanation.

Your body’s preferred fuel is glucose, which comes from carbohydrates. When you eat very little carbohydrate, your blood sugar and insulin levels fall, and the liver begins to break down fat into fatty acids and then into substances called ketones. Ketones are a normal fuel that many tissues, including the brain, can use. When your body is making ketones this way, it is in ketosis. It is also a normal state that occurs during fasting.

How is it different from simply cutting calories?

Dr. Atkins argued that most diets just reduce calories and cause you to lose muscle as well as fat, which slows your metabolism, while a low-carbohydrate diet burns mainly fat. It is true that weight loss by any method can include some loss of muscle, and that is a good reason to eat enough protein and to keep up strength exercise. But studies have not shown that ketosis protects muscle or speeds up metabolism. A large analysis of 48 trials found that low-carbohydrate and low-fat diets led to very similar weight loss after 12 months, about 7 kilograms (roughly 16 pounds) each. The best diet is the one you can stick to.

Is ketosis dangerous?

A common mistake is to think that being in ketosis is dangerous. For most healthy people it is a normal, natural state, and the human body creates ketones to use as fuel when glucose is scarce. It should not be confused with diabetic ketoacidosis, a dangerous emergency in which a person who lacks insulin, usually someone with type 1 diabetes, has very high ketones and high blood sugar. If you have diabetes, kidney or liver disease, or are pregnant or breast-feeding, talk to your doctor before you try a low-carbohydrate diet.

In the first days some people feel tired, get headaches, constipation or bad breath. These effects usually pass, and drinking enough water helps.

How do ketone strips work?

The Atkins books suggest ketone test strips to confirm that you are in ketosis. You hold the strip in your urine stream or dip it in a sample. A chemically treated pad changes color if ketones are present, from pink to purple, and you compare it with the color scale on the bottle. The strips are sold in pharmacies, often near diabetic supplies, and you do not need a prescription. Once you open a bottle they have a limited shelf life, often around six months, so check the label and write the opening date on the box.

How do you read the results?

The strips tell you whether you are making ketones, but they are only a rough guide. If you are in Induction and do not see purple, do not worry. Some people never show more than traces of ketones, or only a color just above the minimum line. You can judge your progress by your weight, your waist and how you feel. If you exercised a few hours before testing, you may not see purple either.

Some dieters wrongly think that the darkest color means they are losing fat faster. In fact, a very dark color mostly means that your urine is concentrated, which can be a sign that you are dehydrated, so drink some water. Ketones also come from fat in your bloodstream, whether you ate it or burned it. If you eat a meal high in fat and then test right away, you will probably see a dark result. Use the strips as a guide and do not get hung up on the color.

How can vegetarians do it?

Vegetarians can follow a low-carbohydrate plan with eggs, cheese, tofu, tempeh, nuts, seeds, avocado, olive oil and non-starchy vegetables, though it takes planning. Our posts on the basics of the Atkins diet, the Atkins induction rules and carbohydrate cravings on Atkins explain how the early weeks work. If you want to read more about ketosis, the Cleveland Clinic has a clear guide.