Energy Balance, Weight Regulation, and Micronutrients

Vocabulary practice cards focusing on energy expenditure, body weight regulation, bariatric interventions, and water- and fat-soluble vitamin metabolism.

Positive energy balance

A state where energy intake exceeds expenditure over time ($\text{in} > \text{out}$), causing stored body energy to tend to rise.

Negative energy balance

A state where energy expenditure exceeds intake ($\text{in} < \text{out}$), leading stored body energy to be metabolized.

Neutral energy balance

A state where energy intake equals expenditure ($\text{in} = \text{out}$), keeping energy stores relatively stable.

3500 kcal per pound rule

An assumption that fails to predict long-term changes because body size, composition, appetite, and expenditure dynamically adapt, while short-term scale changes reflect water and GI contents.

Dynamic weight loss

Nonlinear weight change wherein an initial energy imbalance initiates changes in body mass, prompting energy requirements and expenditure to adapt.

Hunger

The physiological drive to eat food.

Appetite

The psychological desire to eat, which can be stimulated without hunger by sensory, cognitive, social, and environmental cues.

Satiation

Signals developed during an eating episode that lead to the ending of the current meal.

Satiety

A state of fullness that delays the start of the next meal, sustained particularly well by protein, fiber, and water-rich foods.

Bomb calorimeter

An instrument that directly measures food energy by recording heat released during combustion, or indirectly measures it via the volume of oxygen consumed.

Physiological fuel value

The actual number of calories that human bodies derive from consumed food.

Basal metabolism (BMR)

Energy expended to support life-sustaining work at rest under highly controlled resting and fasting conditions; typically the largest component of total energy expenditure.

Resting metabolic rate (RMR)

A measure of energy for basic life-sustaining work at rest assessed under less strict resting and fasting conditions, usually yielding values slightly higher than BMR.

Nonexercise activity thermogenesis (NEAT)

Energy expended on daily movement outside of formal exercise, such as walking, chores, occupational activities, and other movement.

Thermic effect of food (TEF)

The small energetic cost needed to digest, absorb, and metabolize ingested food, typically accounting for about $5\text{--}10\%$ of expenditure, with protein having a higher TEF than fat.

Body mass index (BMI)

A screening metric defined as $\text{weight in kg} \div (\text{height in meters})^2$. Standard categories are underweight ($< 18.5$), healthy range ($18.5\text{ to } < 25$), overweight ($25\text{ to } < 30$), and obesity ($\ge 30$).

Bioelectrical impedance analysis (BIA)

A body composition estimation method in which fluid levels and hydration state influence results.

Dual-energy X-ray absorptiometry (DXA)

A clinical technique that estimates body fat, lean soft tissue, and bone mineral content.

Visceral fat

Adipose tissue that surrounds internal abdominal organs and is strongly linked to cardiometabolic disease risk.

Subcutaneous fat

Adipose tissue stored directly beneath the skin.

Ectopic fat

Lipid accumulation outside of normal adipose tissue depots, such as within liver tissue.

Metabolic syndrome

A cluster of cardiometabolic risk factors—rather than body weight alone—used to assess cardiometabolic health.

Anorexia nervosa

An eating disorder characterized by persistent food restriction, significantly low body weight, an intense fear of gaining weight, or a disturbed evaluation of shape and weight.

Bulimia nervosa

An eating disorder characterized by recurrent episodes of binge eating followed by inappropriate compensatory behaviors.

Binge-eating disorder

An eating disorder characterized by recurrent binge-eating episodes occurring without regular compensatory behaviors.

Hypertrophy (adipose)

An increase in the size of existing fat cells (adipocytes).

Hyperplasia (adipose)

An increase in total fat cell number; during weight loss, adipocytes shrink in size while their total count largely remains.

Lipoprotein lipase (LPL)

An enzyme that releases fatty acids from triglycerides in circulating chylomicrons and VLDL for tissue utilization or storage.

Leptin

A hormone produced primarily by adipose cells that signals stored energy reserves to the brain, generally acting to reduce appetite.

Ghrelin

A hormone produced primarily by the stomach that stimulates hunger, typically rising before planned meals and during periods of energy restriction.

Adaptive thermogenesis

A decrease in energy expenditure that falls beyond what changes in reduced body mass alone predict, favoring weight regain.

Set-point theory

A regulatory model proposing that the body defends a preferred biological weight level, though it is not an unchangeable destiny.

Brown adipose tissue (BAT)

A specialized adipose tissue that expends energy to produce heat via uncoupling proteins.

Prader-Willi syndrome

A rare genetic condition characterized by marked appetite dysregulation and severe early-onset obesity.

Weight stigma

Social bias and discrimination regarding body size that causes psychological distress and reduces healthcare participation.

Sleeve gastrectomy

A bariatric surgical procedure that removes a large portion of the stomach and modifies gut-hormone signaling.

Roux-en-Y gastric bypass

A bariatric surgery that creates a small gastric pouch and reroutes intestinal flow, altering nutrient absorption and gut hormonal responses.

Energy density

The amount of energy per unit weight of food ($\text{kcal/g}$); water and fiber lower it, whereas dietary fats raise it.

Coenzymes

Complex organic helper molecules, frequently derived from B vitamins, that allow specific enzymes to catalyze chemical reactions.

Bioavailability

The proportion of an ingested nutrient that is absorbed and available for metabolic use by the body.

Thiamin (Vitamin B1)

A heat-sensitive water-soluble vitamin converted to TPP to support pyruvate-to-acetyl-CoA reactions; severe deficiency produces beriberi and Wernicke-Korsakoff syndrome.

Riboflavin (Vitamin B2)

A light-sensitive vitamin forming coenzymes FAD and FMN for electron transport; deficiency manifests in lesions of the mouth, tongue, and skin.

Niacin (Vitamin B3)

A vitamin integrated into NAD and NADP coenzymes; severe deficiency results in pellagra (characterized by the 4Ds: dermatitis, diarrhea, dementia, and death).

Biotin

A B vitamin that assists carbon-adding carboxylation reactions; high supplemental doses can interfere with diagnostic tests such as cardiac troponin assays.

Pantothenic acid

A B vitamin essential for the structural backbone of coenzyme A (CoA); dietary deficiency is extremely rare due to widespread food occurrence.

Vitamin B6

A family of vitamers converted to pyridoxal phosphate (PLP) for amino acid metabolism; excessive supplemental intake causes sensory neuropathy, establishing an adult UL of $100\,\text{mg/day}$.

Folate

A water-soluble vitamin required for DNA synthesis and cell division; inadequate periconceptional status increases neural tube defect risk and causes megaloblastic anemia.

Dietary Folate Equivalents (DFE)

A standardized calculation accounting for bioavailability differences: $\mu\text{g DFE} = \mu\text{g food folate} + (1.7 \times \mu\text{g synthetic folic acid consumed with food})$.

Vitamin B12 (Cobalamin)

A cobalt-containing vitamin requiring stomach acid, pepsin, and intrinsic factor for absorption in the ileum; vital for normal erythropoiesis and neurological function.

Choline

An essential nutrient (not officially classified as a vitamin) needed to synthesize acetylcholine, phosphatidylcholine, membrane phospholipids, and maintain normal liver function.

Vitamin C (Ascorbic acid)

A water-soluble antioxidant that stabilizes collagen and enhances nonheme iron absorption; deficiency causes scurvy with poor wound healing and bleeding gums.

Vitamin A

A fat-soluble vitamin encompassing retinol (transport/storage), retinal (vision), and retinoic acid (cell differentiation); severe deficiency causes night blindness and corneal damage.

Vitamin D

A fat-soluble secosteroid formed cutaneous-wise as D3 via UVB exposure or ingested as D2/D3; maintains calcium homeostasis; excessive amounts trigger hypercalcemia with an adult UL of $4{,}000\,\text{IU}\,(100\,\mu\text{g})/\text{day}$.

Rickets and Osteomalacia

Conditions characterized by defective bone mineralization caused by inadequate vitamin D or calcium, occurring in growing children (rickets) or mature adults (osteomalacia).

Vitamin E (Alpha-tocopherol)

A fat-soluble antioxidant that halts free-radical oxidation in polyunsaturated membrane lipids; excessive intake increases hemorrhage risk, yielding an adult UL of $1{,}000\,\text{mg/day}$.

Vitamin K

A fat-soluble vitamin essential for blood clotting and bone protein activation; intake requires consistent dietary monitoring in patients receiving warfarin therapy.

Free radical

An unstable, highly reactive molecular species possessing one or more unpaired electrons in its outer valence shell.

Oxidative stress

A physiological imbalance that occurs when the production of reactive oxygen species exceeds cellular antioxidant defense mechanisms, damaging lipids, proteins, and DNA.

Antioxidants

Substances that neutralize reactive oxygen species and free radicals, terminating cellular chain reactions of oxidative damage.