Keto Terms Glossary: Quick Definitions
This page defines 29 essential keto and low-carb terms, from acetoacetate to total carbs, and links each one to a deeper guide.
Each entry is short by design. Follow its link for measurement limits, clinical context, or fuller physiology, or start with the science of ketosis to see how the terms relate.
What is this glossary, and how is it different from the full glossary?
This page is a compact definition set: 29 terms, one sentence each, for quick lookup. The full keto glossary adds examples, measurement limits, and context for the same subject areas.
Four terms below, ketogenesis, ketone bodies, insulin resistance, and glycemic index, link to dedicated concept pages across the site. Each concept has one canonical definition rather than a duplicate entry.
A–Z keto terms
Acetoacetate (AcAc)
One of the three ketone bodies made during ketogenesis; it can be used directly for fuel by muscles and other tissues, or converted into beta-hydroxybutyrate or acetone.
Acetone
The smallest and most volatile of the three ketone bodies, formed when acetoacetate spontaneously breaks down; it's cleared mostly through the lungs, producing the fruity "keto breath" some people notice.
Beta-Hydroxybutyrate (BHB)
The most abundant ketone body circulating in blood during ketosis, and the one most home blood-ketone meters and exogenous-ketone supplements are built around.
Blood Ketone Meter
A handheld device that measures blood BHB from a small finger-prick sample at one point in time; it does not measure pH, bicarbonate, or total ketone bodies.
Carb Cycling
Alternating low-carb and higher-carb days on a planned schedule, sometimes used by keto dieters around intense training sessions or refeed days.
Electrolytes
Charged minerals, including sodium, potassium, and magnesium, involved in fluid balance and nerve and muscle signaling. Individual needs vary with diet, health, kidney function, and medications.
Exogenous Ketones
Ketone supplements, usually salts or esters, taken to raise blood ketone levels directly, without necessarily producing the metabolic adaptations that come from diet-induced ketosis.
Fatty-Acid Oxidation
The mitochondrial process of breaking fatty acids down into acetyl-CoA units; it feeds both the citric acid cycle for everyday energy and the ketogenesis pathway.
Glucose Ketone Index (GKI)
Blood glucose divided by blood BHB when both are measured in mmol/L; Meidenbauer and colleagues proposed it for metabolic-therapy research in brain cancer, and no validated general-wellness target exists.2
Gluconeogenesis
Regulated glucose production from lactate, glycerol, and glucogenic amino acids, principally in the liver and renal cortex; it continues alongside ketogenesis during carbohydrate restriction.
Glycemic Index
A 0-to-100 scale ranking how quickly a carbohydrate food raises blood glucose relative to pure glucose. See the full comparison of glycemic index vs net carbs for keto for how the two measures relate.
Glycogen
The stored form of glucose in liver and muscle; hepatic glycogen contribution falls during fasting or carbohydrate restriction, with timing varying by intake and activity.
Insulin
A pancreatic hormone that lowers blood glucose and suppresses lipolysis and ketogenesis; its effects interact with counter-regulatory hormones and substrate availability.
Insulin Resistance
A reduced response to insulin's normal signaling, so the pancreas has to release more of it to manage blood sugar. See the full page on insulin resistance and low-carb diets for how it develops and what the evidence says about keto's effect on it.
Keto Adaptation (Fat-Adaptation)
The multi-week process by which the body and brain shift toward burning fat and ketones for fuel more efficiently, which tends to ease early keto side effects like fatigue.
Keto Flu
A non-diagnostic label for nonspecific symptoms reported after starting carbohydrate restriction. Timing and causes vary, and symptoms suggesting an emergency need separate assessment.
Ketoacidosis (DKA)
An emergency requiring diabetes or qualifying hyperglycemia, elevated ketones, and metabolic acidosis. Glucose can be below 200 mg/dL, especially with SGLT2-inhibitor use.1
Ketogenesis
The liver pathway that converts fatty acids into ketone bodies when carbohydrate and glycogen stores run low. See the full explainer: ketogenesis: how your liver makes ketones.
Ketones (Ketone Bodies)
Ketones, or ketone bodies, are acetoacetate, BHB, and acetone. See what ketones are for their metabolism, measurement differences, and DKA safety context.
Ketosis
A metabolic state with increased ketone production and use. Glucose metabolism continues, and onset varies with diet, fasting, activity, and physiology.
Lipolysis
The breakdown of stored triglycerides in fat cells into free fatty acids and glycerol; low insulin accelerates it, supplying the raw material ketogenesis converts into ketones.
Macronutrients (Macros)
Fat, protein, and carbohydrate — the three nutrients measured in grams that make up daily calorie intake and define a person's keto ratio.
MCT Oil
Medium-chain triglyceride oil, a fat absorbed and converted to ketones faster than typical long-chain fats, often added to keto coffee or used as a quick-ketone snack.
Net Carbs
Total carbohydrates minus fiber and non-impact sugar alcohols — the figure keto diets track, since fiber doesn't raise blood sugar or count toward ketosis.
Sodium-Potassium Balance
The relationship between sodium and potassium in fluid, blood-pressure, nerve, and muscle regulation. Kidneys, hormones, intake, health conditions, and medications all affect it.
Sugar Alcohols (Polyols)
Low-calorie sweeteners — erythritol, xylitol, maltitol, and others — that taste sweet but are only partly or fully unabsorbed, so they affect net carbs differently depending on the type.
TDEE (Total Daily Energy Expenditure)
The total number of calories a body burns in a day from resting metabolism, digestion, and activity combined; keto macro calculators start from this number before splitting it into fat, protein, and carb grams.
Therapeutic Ketogenic Diet
A strict, medically supervised protocol — most often a 4:1 ratio of fat to combined protein and carbohydrate — used to treat drug-resistant epilepsy, distinct in precision and purpose from standard weight-loss keto.
Total Carbs
All carbohydrate grams listed on a nutrition label, including fiber and sugar alcohols, before any are subtracted to calculate net carbs.
The terms describe related but distinct processes. During carbohydrate restriction, lipolysis, gluconeogenesis, and ketogenesis can occur together; none can be inferred from one home ketone reading. The science of ketosis shows how the pathways fit together, and the answers hub indexes shorter question-based guides.
Frequently Asked Questions
What does BHB stand for in keto?
What is the difference between total carbs and net carbs?
What is the glucose ketone index (GKI)?
Is keto flu a real medical condition?
What's the difference between exogenous and endogenous ketones?
How is this glossary different from the full keto glossary?
Works cited
Article history
- Merged the duplicate ketone definition; corrected measurement, electrolyte, GKI, ketosis, keto-flu, and DKA definitions
- First published
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