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.
Reading evidence in context
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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
An informal umbrella term for alternating lower- and higher-carbohydrate periods. The label does not establish a validated dose, schedule, performance result, or return-to-ketosis timeline.
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 salts or esters supplied from outside the body. They can acutely raise measured BHB without establishing endogenous ketogenesis, body-fat loss, performance, benefit, or safety.
Fatty-Acid Oxidation
The cellular breakdown of fatty acids, including mitochondrial beta-oxidation that produces acetyl-CoA. The fat may come from food or body stores, so a higher oxidation rate does not prove body-fat loss or benefit.
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 standardized comparison of incremental blood-glucose response after a fixed amount of available carbohydrate against a reference food. It is not simply a digestion-speed score or a prediction for an individual's mixed meal. See glycemic index vs net carbs for keto.
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 signaling in tissues such as muscle, fat, and liver. It is multifactorial, often has no symptoms, and is not diagnosed by one generic fasting-insulin, HOMA-IR, glucose, or ketone value. See insulin resistance and low-carb diets.
Keto Adaptation (Fat-Adaptation)
An informal description of longer-running metabolic changes during sustained carbohydrate restriction. It is not a diagnosis, and no validated symptom checklist, home test, or universal timeline confirms it.
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-mitochondrial pathway that converts acetyl-CoA from fatty-acid oxidation into acetoacetate, BHB, and acetone. It is regulated as a continuum rather than switched on only after glycogen is depleted. See ketogenesis.
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 regulated hydrolysis of stored triglycerides into fatty acids and glycerol. Release alone does not establish that those fatty acids are oxidized, converted into ketones, or lost from body stores.
Macronutrients (Macros)
Fat, protein, and carbohydrate, expressed in grams or as shares of energy. Their targets depend on the dietary or clinical protocol and do not create a universal ketosis threshold.
MCT Oil
A concentrated source of medium-chain triglycerides that can increase ketone production. An acute BHB rise does not establish a broader metabolic state, body-fat loss, benefit, or safety.
Net Carbs
An informal estimate calculated from nutrition-label carbohydrate values using explicitly selected adjustments. The arithmetic depends on the label system and does not predict an individual glucose response or 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)
A carbohydrate category that includes erythritol, xylitol, maltitol, and others. Absorption, energy, labeling, and gastrointestinal effects differ, so one universal net-carb deduction does not apply to every polyol.
TDEE (Total Daily Energy Expenditure)
An estimate of energy used over a day through resting metabolism, digestion, and activity. Equations and activity assumptions mean a calculated TDEE is not a direct measurement or personal target.
Therapeutic Ketogenic Diet
A clinician-directed dietary therapy with protocol-specific formulations, screening, supplementation, monitoring, and follow-up. It is not universally defined by a 4:1 ratio or a GKI target.
Total Carbs
Informal shorthand for the main regulated carbohydrate value. US Total Carbohydrate includes fiber and polyols; EU and UK Carbohydrate excludes fibre but includes polyols.
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
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