Energy Balance and Weight Management

Comprehensive practice flashcards defining essential scientific terms, regulatory hormones, physiological mechanisms, and clinical concepts associated with energy balance and weight management.

Overweight

The condition of being too heavy for one's height, defined as a Body Mass Index (BMI) of $25.0\text{--}29.9\,\text{kg/m}^2$.

Obesity

A condition characterized by excess body fat, defined clinically as a Body Mass Index (BMI) of $30.0\,\text{kg/m}^2$ or greater.

Globesity

A term coined to reflect the global escalation of obesity and overweight, particularly increasing in low- and middle-income nations and urban settings.

Energy Balance

The relationship between the amount of energy consumed in the diet and the amount of energy expended by the body over a given timeframe.

Kilocalorie (kcal)

The standard unit of food energy in North America, representing the amount of heat energy required to raise the temperature of $1\,\text{kg}$ of water by $1\,^\circ\text{C}$.

Bomb Calorimeter

An insulated laboratory instrument that estimates the total chemical energy content of a food by measuring heat released when a dried sample is completely combusted.

Total Energy Expenditure (TEE)

The overall sum of energy expended by the body for basal metabolism, physical activity, processing food, tissue synthesis, and milk production.

Basal Energy Expenditure (BEE)

The energy expended to support an awake, resting body that is not actively digesting food; accounts for approximately $60\%\text{--}75\%$ of total daily energy expenditure.

Basal Metabolic Rate (BMR)

The rate of energy expenditure under strictly resting conditions, measuring life-sustaining metabolic functions while excluding physical activity and digestion.

Resting Energy Expenditure (REE) / Resting Metabolic Rate (RMR)

An estimate of basal metabolism determined by measuring an individual's energy utilization after $5\text{--}6\,\text{hours}$ without food consumption or exercise.

Lean Body Mass

The component of total body mass consisting of non-fat tissue, including bone, skeletal muscle, and internal organs; also referred to as fat-free mass.

Non-Exercise Activity Thermogenesis (NEAT)

Energy expended for all daily physical tasks and spontaneous movements other than sleeping, eating, or deliberate planned exercise, accounting for roughly $15\%\text{--}30\%$ of energy needs.

Thermic Effect of Food (TEF)

The energy required for digesting food, absorbing, metabolizing, and storing nutrients; typically equals approximately $10\%$ of daily energy intake.

Adipocytes

Fat-storing cells constituting adipose tissue that swell when accumulating triglycerides and shrink when stored triglycerides are mobilized for fuel.

Direct Calorimetry

A technique for determining energy expenditure by directly measuring the heat produced by an individual confined inside an insulated chamber.

Indirect Calorimetry

A method estimating energy expenditure by calculating the ratio of oxygen consumed to carbon dioxide exhaled during cellular respiration.

Doubly Labelled Water

A gold-standard technique for tracking total energy expenditure in free-living subjects over up to $2\,\text{weeks}$ by monitoring the clearance of ingested non-radioactive isotopes of hydrogen and oxygen.

Estimated Energy Requirement (EER)

The average dietary energy intake predicted to sustain energy balance in a healthy person based on age, sex, weight, height, and physical activity level.

Comorbidity

The simultaneous presence of two or more medical conditions or disease states in a person, such as obesity co-occurring with type 2 diabetes.

Weight Stigmatization

Negative societal attitudes, bias, discrimination, and mistreatment targeted at people based on their body weight status.

Subcutaneous Fat

Adipose tissue deposited directly under the skin (such as around the hips and thighs) that presents fewer chronic metabolic health risks than abdominal visceral fat.

Visceral Fat

Adipose tissue accumulated deep in the abdominal region surrounding internal organs, associated with insulin resistance, hypertension, and cardiovascular disease.

Bioelectric Impedance Analysis (BIA)

A body composition assessment method that estimates percent body fat by sending an imperceptible electrical current through the body and evaluating tissue resistance to electrical flow.

Skinfold Thickness

A field method for estimating total body fat by using calipers to measure subcutaneous adipose depth at standardized anatomical sites (e.g., triceps and subscapular regions).

Dual-Energy X-ray Absorptiometry (DXA)

A radiological imaging technique using low-energy X-rays to assess body composition by differentiating between bone mineral, lean mass, and adipose tissue.

Set-Point Theory

The concept that internal regulatory mechanisms actively defend a predetermined, stable body weight and fat mass against changes in caloric intake or expenditure.

Hunger

Internal physiological sensations and neurochemical cues that prompt an individual to seek out and consume food.

Satiation

The physiological feeling of fullness that develops during eating and causes an individual to terminate a meal.

Satiety

The prolonged feeling of fullness and satisfaction experienced after a meal that delays hunger and dictates the interval between meals.

Ghrelin

A peptide hormone produced by the stomach that stimulates appetite, rising before meals and dropping after nutrient ingestion.

Cholecystokinin (CCK)

A gastrointestinal hormone released by the small intestine in response to luminal dietary protein and fat that binds to vagal and hypothalamic receptors to induce satiety.

Peptide YY (PYY)

A gut peptide secreted by the distal small intestine and colon in response to nutrient arrival that acts to reduce appetite and food intake.

Leptin

A hormone synthesized and secreted by adipocytes in proportion to fat mass that binds hypothalamic receptors to curb appetite and enhance energy expenditure.

Leptin Resistance

A physiological state in obesity where elevated circulating levels of leptin fail to elicit the typical responses of reduced food intake and increased energy expenditure.

Adaptive Thermogenesis

Modulations in metabolic heat production and energy expenditure caused by environmental stressors, such as ambient temperature shifts or caloric restriction/overeating.

Brown Adipose Tissue

A specialized, highly vascularized adipose tissue rich in mitochondria that expends chemical energy directly as heat rather than storing it as ATP.

Obesogenic Environment

An external setting that promotes weight gain by facilitating excessive caloric consumption and minimizing physical activity.

Weight Cycling (Yo-Yo Dieting)

A recurring pattern of intentional weight loss followed by inadvertent weight regain.

Very-Low-Kcalorie Diet (VLCD)

A medically supervised clinical weight-loss regimen providing fewer than $800\,\text{kcal/day}$, typically implemented as a protein-sparing formula for a maximum of $16\,\text{weeks}$.

Gastric Banding

A restrictive bariatric surgery wherein an adjustable silicone band is placed around the upper stomach to reduce its capacity and slow gastric emptying.

Gastric Bypass

A surgical weight-loss procedure that treats extreme obesity by reducing stomach volume to a small upper pouch and rerouting the gastrointestinal tract past a portion of the small intestine.

Liposuction

A surgical cosmetic procedure that suctions out localized subcutaneous adipose deposits beneath the skin to reshape contours without providing metabolic benefits or systemic weight loss.