Reference
Metabolic Health
Glossary
Plain-English definitions for the terms you'll find across the LifeLedgerX toolbox, blog, and ebook. No jargon walls — just clarity.
A
- A1C (HbA1c)
- A blood test that reflects your average blood sugar over the past two to three months. It measures the percentage of hemoglobin proteins in your red blood cells that have glucose attached. A lower number generally indicates better blood sugar management. Used in: HbA1c Interpreter, Metabolic Health Dashboard
- Adipose tissue
- Your body's fat tissue. It comes in two main forms: subcutaneous (under the skin) and visceral (around organs). Adipose tissue is not just storage — it actively produces hormones and inflammatory signals that affect your metabolic health.
- Autophagy
- Your body's cellular cleanup process, where damaged or dysfunctional cell components are broken down and recycled. It is stimulated by fasting, exercise, and sleep, and plays a role in reducing inflammation and supporting metabolic repair.
B
- Basal metabolic rate (BMR)
- The number of calories your body burns at complete rest just to keep you alive — breathing, circulating blood, maintaining body temperature. It represents the largest portion of your daily energy expenditure. Used in: BMR Calculator, TDEE Calculator
- Blood glucose
- The concentration of sugar (glucose) circulating in your bloodstream at a given moment. Your body tightly regulates this level. When fasting blood glucose stays elevated over time, it can signal developing insulin resistance. Used in: Blood Glucose Interpreter
- Blood pressure
- The force of blood pushing against your artery walls, measured in two numbers: systolic (pressure when your heart beats) over diastolic (pressure between beats). Chronically elevated blood pressure is one of the five criteria used to assess metabolic health. Used in: Metabolic Health Dashboard
- Body mass index (BMI)
- A ratio of your weight to your height, used as a screening tool. It does not measure body fat directly and can be misleading for people with higher muscle mass, different body frames, or certain ethnic backgrounds. It is one data point, not a diagnosis. Used in: BMI Calculator
- Body fat percentage
- The proportion of your total body weight that is fat tissue. It gives a more meaningful picture than weight alone because two people at the same weight can have very different metabolic risk profiles depending on their fat-to-muscle ratio. Used in: Body Fat Estimator
C
- Caloric deficit
- When you consume fewer calories than your body uses in a day. Over time, a sustained deficit leads to weight loss. The size of the deficit matters — too aggressive and your body can respond by slowing its metabolic rate.
- Circadian rhythm
- Your body's internal 24-hour clock that regulates sleep-wake cycles, hormone release, body temperature, and metabolism. Disrupting it — through irregular sleep, late-night eating, or shift work — can impair insulin sensitivity and increase metabolic risk.
- Cortisol
- A hormone produced by your adrenal glands in response to stress. In short bursts it is essential — it raises blood sugar for energy and sharpens focus. When chronically elevated, it promotes fat storage (especially visceral), disrupts sleep, and drives insulin resistance.
- CoQ10 (Coenzyme Q10)
- A compound your body produces naturally that plays a key role in energy production within your cells. Statin medications can deplete CoQ10 levels, which is why supplementation is sometimes discussed alongside cholesterol-lowering drugs.
D
- Deep sleep
- The stage of sleep where your body does its most intensive physical repair, consolidates memory, and releases growth hormone. It is the most restorative stage and typically occurs in longer stretches during the first half of the night.
- Diastolic pressure
- The bottom number in a blood pressure reading. It represents the pressure in your arteries between heartbeats, when your heart is resting and refilling with blood.
- DKA (Diabetic ketoacidosis)
- A dangerous medical emergency where ketone levels rise to extreme levels alongside very high blood sugar, most commonly in type 1 diabetes. It is fundamentally different from the mild, controlled ketosis that can occur during fasting or low-carb eating in metabolically healthy people.
- Dyslipidemia
- An imbalance in blood lipid levels — typically elevated triglycerides, elevated LDL cholesterol, low HDL cholesterol, or some combination. It is one of the metabolic markers that signal increased cardiovascular risk.
E
- eAG (Estimated average glucose)
- A calculated value derived from your A1C result that translates the percentage into an estimated daily blood sugar average in mg/dL or mmol/L. It helps you relate your A1C to the kind of numbers you see on a glucose meter. Used in: HbA1c Interpreter
- Electrolytes
- Minerals in your body — including sodium, potassium, and magnesium — that carry electrical charges and regulate muscle function, hydration, nerve signaling, and pH balance. They become especially important during fasting, exercise, and dietary changes.
F
- Fasting glucose
- Your blood sugar level measured after at least 8 hours without eating. It gives a snapshot of how well your body manages glucose overnight. Consistently elevated fasting glucose is an early signal of insulin resistance.
- Fasting insulin
- The level of insulin in your blood after fasting. Even when fasting glucose looks normal, elevated fasting insulin can reveal that your pancreas is working harder than it should to keep blood sugar in range — an early marker of metabolic trouble. Used in: Fasting Insulin Interpreter, HOMA-IR Calculator
- Ferritin
- A protein that stores iron in your body. A ferritin blood test reflects your iron reserves. Both very low and very high levels are worth paying attention to — low can mean depletion, high can signal inflammation or iron overload.
G
- Ghrelin
- A hormone produced mainly in your stomach that signals hunger to your brain. It rises before meals and drops after eating. Sleep deprivation increases ghrelin, which is one reason poor sleep makes you hungrier.
- Glucagon
- A hormone produced by your pancreas that raises blood sugar by telling your liver to release stored glucose. It works in opposition to insulin — when insulin is low (during fasting), glucagon rises to keep your brain and body fueled.
- Gluconeogenesis
- The process by which your liver creates new glucose from non-carbohydrate sources like protein and lactate. It keeps your blood sugar stable during extended fasting or very low carbohydrate intake.
- Glycogen
- The stored form of glucose, held in your liver and muscles. Your body draws on glycogen first when it needs quick energy. Once glycogen stores are depleted — during fasting or prolonged exercise — your body shifts more toward burning fat.
H
- HDL cholesterol
- High-density lipoprotein — often called "good cholesterol" because it helps remove excess cholesterol from your bloodstream and transport it back to your liver. Higher HDL levels are generally associated with lower cardiovascular risk. Used in: Lipid Panel Interpreter, Metabolic Health Dashboard
- Heart rate zones
- Ranges of heartbeats per minute that correspond to different exercise intensities, from light recovery through maximum effort. Training in specific zones targets different energy systems — fat burning, aerobic endurance, or peak cardiovascular capacity. Used in: Heart Rate Zones Calculator
- HOMA-IR
- Homeostatic Model Assessment of Insulin Resistance. A calculated score using fasting insulin and fasting glucose that estimates how resistant your cells are to insulin. Higher values suggest your body needs more insulin to manage the same amount of glucose. Used in: HOMA-IR Calculator
- hs-CRP (High-sensitivity C-reactive protein)
- A blood marker that measures low-grade systemic inflammation. Your liver produces CRP in response to inflammation anywhere in the body. Persistently elevated hs-CRP is associated with increased cardiovascular risk, independent of cholesterol levels. Used in: hs-CRP Interpreter
- Hyperinsulinemia
- A condition where insulin levels in the blood remain higher than expected. It often develops alongside insulin resistance — your pancreas produces more insulin to compensate for cells that are not responding efficiently. It can exist for years before blood sugar levels show any change.
I
- Inflammation
- Your body's immune response to injury or threat. Acute inflammation (a cut, an infection) is protective. Chronic low-grade inflammation — driven by poor sleep, stress, visceral fat, and processed food — is a root driver of metabolic dysfunction and cardiovascular disease.
- Insulin
- A hormone produced by your pancreas that acts like a key, unlocking your cells so they can absorb glucose from the bloodstream for energy. When your cells stop responding efficiently to insulin, glucose stays elevated and your pancreas works harder — the beginning of insulin resistance.
- Insulin resistance
- A condition where your cells become less responsive to insulin's signal, requiring your pancreas to produce increasingly more insulin to keep blood sugar in range. It is considered the central driver of metabolic syndrome and often develops years before diabetes is diagnosed. Used in: HOMA-IR Calculator, TyG Index Calculator
- Intermittent fasting
- An eating pattern that cycles between periods of eating and fasting. Common approaches include 16:8 (16 hours fasting, 8 hours eating) and 18:6. It can improve insulin sensitivity, promote autophagy, and support metabolic flexibility — but is not appropriate for everyone.
K
- Ketones
- Molecules your liver produces from fat when glucose is limited — during fasting, very low carbohydrate intake, or prolonged exercise. They serve as an alternative fuel source, especially for your brain. Mild ketosis is a normal metabolic state; extremely high levels (DKA) are a medical emergency.
- Ketosis
- A metabolic state where your body is primarily burning fat and producing ketones for fuel instead of relying on glucose. Nutritional ketosis (mild, controlled) is fundamentally different from diabetic ketoacidosis (DKA), which is a dangerous emergency.
L
- LDL cholesterol
- Low-density lipoprotein — often called "bad cholesterol" because elevated levels are associated with plaque buildup in arteries. However, LDL particle size and count matter more than the total number alone. Small dense LDL particles carry higher risk than large buoyant ones. Used in: Lipid Panel Interpreter
- Lean body mass
- Everything in your body that is not fat — muscles, bones, organs, water, connective tissue. Knowing your lean body mass helps contextualize your weight and informs more accurate calorie and protein calculations. Used in: Lean Body Mass Calculator
- Leptin
- A hormone produced by your fat cells that signals fullness to your brain. In theory, more body fat means more leptin and less hunger. In practice, chronically high leptin levels can lead to leptin resistance — your brain stops hearing the signal, and hunger persists despite adequate energy stores.
- Lipid panel
- A standard blood test that measures total cholesterol, LDL, HDL, and triglycerides. It provides a snapshot of your blood fat profile. The ratios between these values — particularly triglyceride-to-HDL — often tell a more useful metabolic story than any single number. Used in: Lipid Panel Interpreter
M
- Macronutrients
- The three categories of nutrients your body needs in large amounts: protein (builds and repairs), carbohydrates (primary fuel source), and fat (hormones, cell structure, energy storage). The ratio between them affects blood sugar, satiety, and metabolic response. Used in: Macronutrient Calculator
- Magnesium
- A mineral involved in over 300 processes in your body, including muscle relaxation, nerve function, blood sugar regulation, and sleep quality. Many people are deficient without knowing it, and certain medications (like proton pump inhibitors) can further deplete levels.
- Melatonin
- A hormone your brain produces in response to darkness that signals your body it is time to sleep. Light exposure at night suppresses melatonin production, which is why screen time before bed and artificial lighting can disrupt your circadian rhythm and sleep quality.
- Metabolic flexibility
- Your body's ability to switch efficiently between burning glucose and burning fat for fuel depending on what is available. A metabolically flexible person can fast comfortably, exercise without crashing, and maintain stable energy. Insulin resistance reduces metabolic flexibility.
- Metabolic health
- The state of having healthy blood sugar, triglycerides, HDL cholesterol, blood pressure, and waist circumference — without the need for medication. These five markers define metabolic syndrome when they are out of range. Fewer than one in three adults meet all five criteria.
- Metabolic syndrome
- A cluster of interconnected conditions — elevated blood sugar, high triglycerides, low HDL, high blood pressure, and excess waist circumference — that together significantly increase the risk of type 2 diabetes, heart disease, and stroke. Having three or more of these markers qualifies as metabolic syndrome. Used in: Metabolic Health Dashboard
N
- NAC (N-Acetyl Cysteine)
- A supplement form of the amino acid cysteine that supports your body's production of glutathione, a powerful antioxidant. It is sometimes discussed in the context of liver health, inflammation, and respiratory support.
- NEAT (Non-exercise activity thermogenesis)
- The energy your body burns through everyday movement that is not formal exercise — walking, fidgeting, standing, cooking, carrying groceries. NEAT can vary by hundreds of calories per day between people and often drops unconsciously when you restrict calories.
O
- Omega-3 fatty acids
- Essential fats your body cannot produce on its own, found in fatty fish, flaxseed, and walnuts. They play a role in reducing inflammation, supporting heart health, and improving cell membrane function. The ratio of omega-3 to omega-6 in your diet influences your inflammatory balance.
P
- Prediabetes
- A condition where blood sugar levels are higher than normal but not yet high enough for a type 2 diabetes diagnosis. It is a warning window — most people with prediabetes have no symptoms. A1C between 5.7% and 6.4% or fasting glucose between 100 and 125 mg/dL falls in this range.
R
- REM sleep
- Rapid eye movement sleep — the stage where most dreaming occurs and your brain processes emotional memories and learning. REM tends to increase in the second half of the night, which is one reason cutting sleep short disproportionately reduces REM time.
- Resting heart rate
- The number of times your heart beats per minute when you are completely at rest. A lower resting heart rate generally indicates better cardiovascular fitness. It can also serve as a daily signal — a sudden increase may reflect stress, poor sleep, illness, or overtraining.
S
- Systolic pressure
- The top number in a blood pressure reading. It measures the pressure in your arteries when your heart contracts and pushes blood out. Consistently elevated systolic pressure is a significant cardiovascular risk factor.
T
- TDEE (Total daily energy expenditure)
- The total number of calories your body burns in a full day, combining your basal metabolic rate, the thermic effect of food, NEAT, and any deliberate exercise. Understanding your TDEE is the starting point for any calorie-based nutrition plan. Used in: TDEE Calculator
- Thermic effect of food (TEF)
- The energy your body uses to digest, absorb, and process the food you eat. Protein has the highest thermic effect (20–30% of its calories are burned during digestion), followed by carbohydrates (5–10%), then fat (0–3%).
- Time-restricted eating
- A form of intermittent fasting focused on limiting your eating to a consistent daily window — for example, eating only between 10 AM and 6 PM. The emphasis is on aligning your eating pattern with your circadian rhythm rather than on calorie restriction.
- Triglycerides
- The most common type of fat in your blood. Your body converts excess calories — especially from carbohydrates and alcohol — into triglycerides for storage. Elevated triglycerides, particularly in combination with low HDL, are a strong signal of insulin resistance. Used in: Lipid Panel Interpreter, Metabolic Health Dashboard
- TyG index
- A calculated marker of insulin resistance using fasting triglycerides and fasting glucose. It serves as an accessible alternative to direct insulin measurement — useful when fasting insulin is not available on your lab work. Used in: TyG Index Calculator
- Type 2 diabetes
- A metabolic condition where your body either does not produce enough insulin or your cells have become so resistant to insulin that blood sugar remains chronically elevated. It typically develops over years through progressive insulin resistance and is the condition most directly linked to metabolic syndrome.
V
- Visceral fat
- Fat stored deep inside your abdomen, surrounding your organs. Unlike subcutaneous fat (under the skin), visceral fat is metabolically active — it releases inflammatory chemicals and hormones that increase your risk of insulin resistance, heart disease, and type 2 diabetes. Waist circumference is the simplest proxy for visceral fat.
- Vitamin D
- A fat-soluble vitamin your body produces when exposed to sunlight. It plays a role in immune function, bone health, mood regulation, and insulin sensitivity. Deficiency is widespread, particularly in people who live at higher latitudes, have darker skin, or spend limited time outdoors.
W
- Waist circumference
- A measurement around your midsection that serves as a practical indicator of visceral fat. It is one of the five metabolic syndrome criteria. Risk thresholds vary by sex and ethnicity — for most men, above 40 inches (102 cm) is elevated; for most women, above 35 inches (88 cm). Used in: Waist Ratio Tools, Metabolic Health Dashboard
- WHR (Waist-to-hip ratio)
- Your waist circumference divided by your hip circumference. It indicates where your body stores fat — a higher ratio means more abdominal fat relative to your hips, which is associated with greater metabolic risk regardless of overall weight. Used in: Waist Ratio Tools
- WHtR (Waist-to-height ratio)
- Your waist circumference divided by your height. A value above 0.5 generally indicates increased metabolic risk. It is considered by many researchers to be a better screening tool than BMI because it accounts for both body size and fat distribution. Used in: Waist Ratio Tools
Z
- Zinc
- An essential trace mineral involved in immune function, wound healing, taste perception, and insulin storage. Your body does not store zinc long-term, so consistent dietary intake matters. Proton pump inhibitors and certain other medications can reduce zinc absorption.
No terms match your search. Try a different keyword.