Glossary section

Lipolysis

The breakdown of stored triglycerides into free fatty acids and glycerol, triggered by hormones like adrenaline and glucagon.

Beta-Oxidation

The core cellular process of chopping fatty acid chains into Acetyl-CoA inside the mitochondria.

Triglycerides

The storage form of fat in the body, three fatty acid chains attached to a glycerol backbone, held inside fat cells (adipocytes).

Free Fatty Acids

Fatty acids released from triglycerides during lipolysis that travel through the bloodstream to be used as fuel.

Glycerol

The backbone molecule released when triglycerides are broken down; can be converted to glucose by the liver.

Acetyl-CoA

A 2-carbon molecule produced by beta-oxidation that feeds into the Krebs Cycle for energy production.

Lipolytic cascade

The sequence of molecular events from hormone binding → cAMP → PKA → HSL/Perilipin phosphorylation → triglyceride breakdown.

Lipolytic

Describing a substance or process that promotes the breakdown of fat, e.g. catecholamines, fasting, and exercise are lipolytic.

Adipocytes

Fat cells, specialized cells that store energy as triglycerides in large lipid droplets.

Adipose tissue

Body fat tissue composed of adipocytes; acts as the body's primary long-term energy reserve.

Mitochondria

The cell's power plants, organelles where fatty acids and glucose are converted into ATP through oxidative phosphorylation.

BAT

Brown Adipose Tissue, fat tissue rich in mitochondria that burns calories as heat via UCP1; activated by cold exposure.

WAT

White Adipose Tissue, conventional fat tissue that stores energy as triglycerides; the dominant type in most adults.

Beiging

The process by which white fat cells develop brown fat characteristics (more mitochondria, UCP1 expression) in response to cold exposure or exercise.

HSL

Hormone-Sensitive Lipase, the enzyme that breaks down stored triglycerides inside fat cells when activated by PKA.

ATGL

Adipose Triglyceride Lipase, initiates the first step of lipolysis, cleaving the first fatty acid from a triglyceride molecule.

CPT1

Carnitine Palmitoyltransferase 1, the gatekeeper enzyme that transfers fatty acids across the inner mitochondrial membrane for oxidation.

CPT-1

Carnitine Palmitoyltransferase 1, the gatekeeper enzyme that transfers fatty acids into the mitochondria; blocked when insulin/malonyl-CoA levels are high.

Perilipin-1

A protein coating fat droplets inside adipocytes; must be phosphorylated before HSL can access and break down stored triglycerides.

PKA

Protein Kinase A, an enzyme activated by cAMP that phosphorylates HSL and Perilipin-1, triggering lipolysis.

PGC-1α

Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha, the master regulator of mitochondrial biogenesis; activated by exercise, fasting, and cold.

SIRT1

Sirtuin 1, a longevity protein activated by AMPK that deacetylates and activates PGC-1α, amplifying fat-burning gene expression.

PPAR

Peroxisome Proliferator-Activated Receptors, a family of nuclear receptors that regulate fat metabolism genes; activated by fatty acids and exercise.

JAK2

Janus Kinase 2, part of the GH receptor signalling pathway that activates STAT5 to upregulate fat-burning enzymes.

STAT5

Signal Transducer and Activator of Transcription 5, activated by growth hormone signalling to promote lipolysis in adipocytes.

UCP1

Uncoupling Protein 1, the protein in brown fat that 'uncouples' the electron transport chain, releasing energy as heat instead of ATP.

Phosphodiesterase

An enzyme that breaks down cAMP; caffeine inhibits this enzyme, extending cAMP's lipolytic signal.

Malonyl-CoA

A metabolic intermediate that directly inhibits CPT-1, blocking fat entry into mitochondria; suppressed when insulin is low.

AMPK

AMP-activated Protein Kinase, a cellular fuel sensor activated by exercise and fasting that switches the body into fat-burning mode and drives mitochondrial biogenesis.

cAMP

Cyclic AMP, a second messenger molecule that activates Protein Kinase A (PKA), triggering the lipolysis cascade.

Adenosine

A neurotransmitter that promotes sleep and reduces metabolic rate; caffeine works by blocking adenosine receptors.

EGCG

Epigallocatechin Gallate, the active polyphenol in green tea that activates AMPK and inhibits fat breakdown inhibition enzymes.

Polyphenols

Plant-based micronutrients (found in berries, green tea, olive oil) with antioxidant effects that activate fat-burning pathways like AMPK.

Cytokines

Small signalling proteins released by immune cells; pro-inflammatory cytokines like IL-6 and TNF-alpha impair insulin signalling and promote fat storage.

Heat shock proteins

Protective proteins induced by heat stress (sauna) that repair cellular damage and improve mitochondrial function.

Insulin

A storage hormone released by the pancreas when blood sugar rises; inhibits fat oxidation and promotes fat and glycogen storage.

Cortisol

The primary stress hormone produced by the adrenal glands; chronically elevated cortisol promotes visceral fat storage and muscle breakdown.

Catecholamines

Hormones including adrenaline (epinephrine) and noradrenaline (norepinephrine) that trigger fight-or-flight responses, elevate metabolic rate, and stimulate fat release.

Adrenaline

Also called epinephrine, a catecholamine hormone that activates fat release (lipolysis) by binding to beta-adrenergic receptors on fat cells.

Noradrenaline

Also called norepinephrine, a catecholamine that stimulates fat burning, increases focus, and is elevated by cold exposure and intense exercise.

Epinephrine

The scientific name for adrenaline, a catecholamine that triggers rapid fatty acid release from fat cells.

Norepinephrine

The scientific name for noradrenaline, released by the sympathetic nervous system to increase lipolysis and metabolic rate.

Growth Hormone

A pituitary hormone (GH) that directly activates hormone-sensitive lipase to break down stored fat; 60-70% of daily GH is released during deep sleep.

Testosterone

The primary anabolic hormone; supports muscle synthesis, metabolic rate, and fat oxidation, synthesised primarily during REM sleep.

Leptin

The satiety hormone produced by fat cells; signals the brain to reduce hunger and increase metabolic rate; drops during prolonged caloric restriction.

Ghrelin

The hunger hormone released by the stomach; rises with poor sleep and caloric restriction, driving appetite and cravings.

Glucagon

A hormone released by the pancreas when blood sugar is low; triggers lipolysis and liver glycogen breakdown to raise blood sugar.

IGF-1

Insulin-like Growth Factor 1, promotes muscle growth and repair; elevated by sauna use and growth hormone release.

Glucocorticoid

A class of steroid hormones (including cortisol) that regulate metabolism and immune responses via glucocorticoid receptors.

Glucocorticoid receptor

A protein in cells that binds cortisol and triggers gene expression changes, found at high density in visceral fat, driving abdominal fat accumulation under chronic stress.

ATP

Adenosine Triphosphate, the body's universal energy currency; every cellular process runs on ATP.

NAD

Nicotinamide Adenine Dinucleotide, an electron carrier that picks up electrons from fat and glucose breakdown, becoming NADH to deliver them to the Electron Transport Chain.

NAD+

Nicotinamide Adenine Dinucleotide (oxidised form), an electron carrier that picks up electrons from fat and glucose breakdown, becoming NADH to deliver them to the Electron Transport Chain.

NADH

The reduced (electron-loaded) form of NAD+; shuttles high-energy electrons from beta-oxidation and the Krebs Cycle to the Electron Transport Chain to drive ATP production.

FAD

Flavin Adenine Dinucleotide (oxidised form), an electron carrier that accepts electrons during fat and carbohydrate metabolism, becoming FADH₂.

FADH2

The reduced form of FAD; carries electrons from beta-oxidation and the Krebs Cycle to the Electron Transport Chain, contributing to ATP synthesis.

FADH₂

The reduced form of FAD; carries electrons from beta-oxidation and the Krebs Cycle to the Electron Transport Chain, contributing to ATP synthesis.

Krebs Cycle

Also called the TCA cycle, a series of reactions inside mitochondria that extracts energy from Acetyl-CoA, producing NADH and FADH₂.

Electron Transport Chain

The final stage of cellular respiration inside mitochondria where NADH and FADH₂ are used to generate bulk ATP.

Oxidative phosphorylation

The process by which mitochondria produce ATP using electrons from fat and carbohydrate metabolism.

Phosphocreatine

A high-energy molecule stored in muscle cells that rapidly regenerates ATP during short, maximal bursts of exercise.

Creatine

A naturally occurring compound that replenishes phosphocreatine stores in muscles, enabling higher intensity efforts and muscle preservation.

Metabolic rate

The speed at which the body burns calories at rest and during activity; influenced by muscle mass, hormones, and thyroid function.

TDEE

Total Daily Energy Expenditure, the total calories your body burns per day including exercise and basic functions.

NEAT

Non-Exercise Activity Thermogenesis, calories burned through all movement outside of formal exercise (walking, fidgeting, standing).

Insulin resistance

A condition where cells stop responding properly to insulin, requiring more insulin to move glucose, associated with excess fat storage and metabolic disease.

Insulin sensitivity

How effectively cells respond to insulin; higher sensitivity means less insulin is needed, favouring fat burning over fat storage.

Leptin resistance

A state where the brain stops responding to leptin's satiety signal, causing persistent hunger despite adequate fat stores.

Adipogenesis

The process of forming new fat cells from precursor cells (pre-adipocytes); promoted by high cortisol and high insulin environments.

Lipogenesis

The process of converting carbohydrates or excess calories into new fat for storage; accelerated by high insulin and excess calories.

Visceral fat

Fat stored deep in the abdomen around organs; metabolically active and strongly linked to insulin resistance, cortisol, and cardiovascular risk.

Subcutaneous fat

Fat stored just beneath the skin; less metabolically harmful than visceral fat and more responsive to exercise.

Caloric deficit

Consuming fewer calories than the body burns; the fundamental driver of fat loss when combined with adequate protein and exercise.

Thermic effect

The energy cost of digesting and processing food; protein has the highest thermic effect (20 - 30% of its calories are burned in digestion).

Glycogen

The storage form of carbohydrates in muscle and liver; depleted during exercise and fasting, which signals the body to shift toward fat burning.

Ketones

Alternative fuel molecules (e.g. beta-hydroxybutyrate) produced by the liver from fatty acids during carb restriction or fasting; can fuel the brain.

Carnitine

A naturally occurring molecule that transports long-chain fatty acids across the mitochondrial membrane to be oxidised for energy.

EPOC

Excess Post-Exercise Oxygen Consumption, elevated metabolism lasting 12 - 48 hours after intense exercise, primarily fuelled by fat oxidation.

HIIT

High-Intensity Interval Training, alternating bursts of maximum effort with short rest periods; triggers EPOC and long-term metabolic adaptations.

Zone 2

A cardio intensity of ~60 - 70% maximum heart rate where fat oxidation is maximised per unit of time and mitochondrial density is built.

VO2 max

Maximum oxygen uptake, the gold standard measure of aerobic fitness and cardiovascular capacity.

Autophagy

The cell's self-cleaning process, damaged organelles and proteins are broken down and recycled; strongly triggered by fasting and exercise.

Mitochondrial biogenesis

The process of growing new mitochondria inside cells, triggered by exercise and fasting, increases fat-burning capacity.

HPA axis

Hypothalamic-Pituitary-Adrenal axis, the hormonal stress response system that controls cortisol release; chronic activation leads to visceral fat gain.

Cortisol

The primary stress hormone produced by the adrenal glands; chronically elevated cortisol promotes visceral fat storage and muscle breakdown.

Testosterone

The primary anabolic hormone; supports muscle synthesis, metabolic rate, and fat oxidation, synthesised primarily during REM sleep.

T3

Triiodothyronine, the active thyroid hormone that sets the speed of your resting metabolism; drops during severe caloric restriction.

Thyroid

An endocrine gland in the neck that produces T3 and T4 hormones regulating metabolic rate, body temperature, and energy expenditure.

Omega-3

Essential polyunsaturated fatty acids (EPA + DHA) found in fish oil that reduce inflammation, improve insulin sensitivity, and support fat cell receptor function.

EPA

Eicosapentaenoic acid, an omega-3 fatty acid that reduces inflammatory cytokines and improves insulin signalling.

DHA

Docosahexaenoic acid, an omega-3 fatty acid essential for brain function and cell membrane integrity; found in fish oil.

Magnesium

An essential mineral required for over 300 enzymatic reactions including ATP production and insulin signalling; frequently depleted in athletes.

Zinc

An essential trace mineral required for testosterone synthesis and thyroid hormone conversion; deficiency reduces metabolic rate.

Carnitine

A naturally occurring molecule that transports long-chain fatty acids across the mitochondrial membrane to be oxidised for energy.

Creatine

A naturally occurring compound that replenishes phosphocreatine stores in muscles, enabling higher intensity efforts and muscle preservation.

HRV

Heart Rate Variability, the variation in time between heartbeats; a reliable marker of recovery status and autonomic nervous system health.

Beta-adrenergic receptors

Cell surface receptors on fat cells that bind catecholamines (adrenaline/noradrenaline) to initiate the lipolytic cascade.

Slow-wave sleep

The deepest stage of non-REM sleep (stages 3 - 4) during which 60 - 70% of daily growth hormone is released and cellular repair is maximised.

REM sleep

Rapid Eye Movement sleep, the dreaming phase of sleep during which testosterone is primarily synthesised and memory is consolidated.