Keto Glossary: 29 Essential Keto Terms Defined

This glossary defines 29 keto terms in five groups: ketone chemistry, carbohydrates and macronutrients, metabolism, safety and measurement, and therapeutic use. Each entry links to a longer guide.

The vocabulary comes from biochemistry, nutrition labels, and laboratory testing. Distinctions such as ketosis versus ketoacidosis and net carbs versus total carbs matter because the paired terms are not interchangeable. Start with the science of ketosis, keto diet basics, or calculating your macros for context, then use this page for lookup.

Ketone chemistry

Ketone bodies are acetoacetate, D-BHB, and acetone. Hepatic production increases during fasting, sustained carbohydrate restriction, and some periods of prolonged exercise.

Term	One-line definition
Ketones (ketone bodies)	Acetoacetate, BHB, and acetone, a metabolically related group produced during ketogenesis.
Beta-Hydroxybutyrate (BHB)	The most abundant ketone, and the one blood meters measure directly.
Acetoacetate	The first ketone the liver produces; the one urine strips detect.
Acetone	A volatile ketone exhaled through the lungs, responsible for "keto breath."

Carbs & macros

This cluster separates dietary targets from regulated label terms. “Net carbs” is informal arithmetic, and the correct starting value differs between US and EU/UK labels.

Term	One-line definition
Net Carbs	An informal label-based estimate whose arithmetic depends on the label system and selected adjustments.
Total Carbs	The regulated label carbohydrate value; US Total Carbohydrate includes fiber, while EU/UK Carbohydrate excludes fibre.
Macronutrients (Macros)	Fat, protein, and carbohydrate — the three nutrients whose ratio defines keto.
Sugar Alcohols (Polyols)	Carbohydrate sweeteners whose absorption, fermentation and glycemic effects differ by compound.
Glycemic Index	A 0–100 scale of how fast a carb food raises blood sugar.
TDEE (Total Daily Energy Expenditure)	The total calories you burn daily — the starting point for setting keto macros.

Metabolism & mechanisms

These terms describe what's happening inside the body during ketosis, from the hormone that gates fat-burning to the process that becomes second nature once you're fat-adapted.

Term	One-line definition
Ketosis	A state of increased ketone production and use; glucose metabolism continues.
Gluconeogenesis	Regulated glucose production from lactate, glycerol, and glucogenic amino acids, mainly in the liver and renal cortex.
Glycogen	Stored glucose in liver and muscle; its contribution changes with intake, fasting, and activity.
Insulin	A hormone that suppresses lipolysis and ketogenesis while helping regulate blood glucose.
Lipolysis	The breakdown of stored fat into fatty acids the liver can turn into ketones.
Fatty Acid Oxidation	The process of burning fatty acids for energy, upstream of ketone production.
Insulin Resistance	Reduced cell response to insulin, a driver of type 2 diabetes that low-carb diets may help.
Keto-Adaptation (Fat-Adapted)	The weeks-long adjustment to becoming efficient at burning fat and ketones.

Safety & measurement

This cluster covers how ketosis is tested and, critically, how nutritional ketosis differs from the medical emergency ketoacidosis. Read the DKA entry first if you're worried about a symptom.

Term	One-line definition
Ketoacidosis (DKA)	A dangerous blood-acid emergency, mostly in diabetics — not the same as nutritional ketosis.
Keto Flu	A non-diagnostic label for nonspecific symptoms reported after starting carbohydrate restriction; timing and causes vary.
Blood Ketone Meter	A finger-prick device that measures blood BHB at one point in time.
Ketone Urine Strips	Semi-quantitative strips that detect urine acetoacetate; hydration, renal handling, and timing affect the result.
Glucose Ketone Index (GKI)	Glucose mmol/L divided by blood BHB mmol/L; proposed for metabolic-therapy research without a validated wellness target.
Electrolytes	Charged minerals, including sodium, potassium, magnesium, and calcium, involved in fluid, nerve, and muscle function.
Sodium-Potassium Balance	The relationship between two electrolytes involved in fluid, blood-pressure, nerve, and muscle regulation.

Advanced & therapeutic keto

These terms cover keto beyond the standard weight-loss version — fat sources that raise ketones fast, cycling protocols, and the medically supervised diet used for clinical conditions.

Term	One-line definition
Exogenous Ketones	Supplemental BHB salts or esters taken to raise blood ketones from outside the diet.
MCT Oil	A fat rapidly converted to ketones by the liver, faster than other dietary fats.
Carb Cycling	Alternating higher- and lower-carb days, used by some athletes and advanced dieters.
Therapeutic Ketogenic Diet	A stricter, medically supervised keto protocol used to treat drug-resistant epilepsy.

How is this glossary organized?

The 29 terms are grouped into five clusters — ketone chemistry, carbs and macros, metabolism, safety and measurement, and advanced or therapeutic keto — so related concepts sit together instead of in one long alphabetical list. Start with whichever cluster matches your question, then follow the internal links between entries; most terms cross-reference two to eight related terms.

If you're new to keto, start with keto diet basics and the science of ketosis for the full picture, then use this glossary as a lookup while you read. If you're dialing in your numbers, calculating your macros walks through the net-carb and macro math referenced throughout the Carbs & Macros cluster above.

Frequently Asked Questions

What's the difference between ketosis and ketoacidosis?

Nutritional ketosis does not ordinarily include metabolic acidosis. DKA requires diabetes or qualifying hyperglycemia, elevated ketones, and metabolic acidosis; euglycemic DKA can occur below 200 mg/dL, particularly with SGLT2-inhibitor use.

What are the three ketone bodies?

Beta-hydroxybutyrate (BHB), acetoacetate, and acetone. BHB is the most abundant and the one blood meters measure; acetoacetate is what urine strips detect; acetone is exhaled and causes keto breath.

Is net carbs the same as the carbohydrate value on a label?

No. Net carbs is an informal estimate. On a US label, a method may subtract selected fiber, polyol or allulose adjustments from Total Carbohydrate. On an EU or UK label, Carbohydrate already excludes fibre, so fibre must not be subtracted again. There is no universal polyol deduction.

How is being fat-adapted different from just being in ketosis?

Ketosis describes increased ketone production and use and can begin within days. Keto-adaptation refers to longer-running changes in fuel transport and oxidation; timing and study markers vary.

Do I need a blood ketone meter to do keto?

No. Most people can follow keto using net-carb targets alone. A blood ketone meter is useful if you want to confirm ketosis directly, are doing a stricter therapeutic protocol, or want to track your glucose ketone index.

Article history

1. August 23, 2026Merged duplicate ketone entries, updated canonical links, corrected physiology and DKA definitions, and aligned net-carbohydrate definitions with US and EU/UK labels
2. August 19, 2026First published