Body Weight: The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.Weight Gain: Increase in BODY WEIGHT over existing weight.Weight Loss: Decrease in existing BODY WEIGHT.Birth Weight: The mass or quantity of heaviness of an individual at BIRTH. It is expressed by units of pounds or kilograms.Molecular Weight: The sum of the weight of all the atoms in a molecule.Obesity: A status with BODY WEIGHT that is grossly above the acceptable or desirable weight, usually due to accumulation of excess FATS in the body. The standards may vary with age, sex, genetic or cultural background. In the BODY MASS INDEX, a BMI greater than 30.0 kg/m2 is considered obese, and a BMI greater than 40.0 kg/m2 is considered morbidly obese (MORBID OBESITY).Organ Size: The measurement of an organ in volume, mass, or heaviness.Eating: The consumption of edible substances.Body Composition: The relative amounts of various components in the body, such as percentage of body fat.Energy Intake: Total number of calories taken in daily whether ingested or by parenteral routes.Fetal Weight: The weight of the FETUS in utero. It is usually estimated by various formulas based on measurements made during PRENATAL ULTRASONOGRAPHY.Body Mass Index: An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)Energy Metabolism: The chemical reactions involved in the production and utilization of various forms of energy in cells.Infant, Low Birth Weight: An infant having a birth weight of 2500 gm. (5.5 lb.) or less but INFANT, VERY LOW BIRTH WEIGHT is available for infants having a birth weight of 1500 grams (3.3 lb.) or less.Diet: Regular course of eating and drinking adopted by a person or animal.Diet, Reducing: A diet designed to cause an individual to lose weight.Adipose Tissue: Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Leptin: A 16-kDa peptide hormone secreted from WHITE ADIPOCYTES. Leptin serves as a feedback signal from fat cells to the CENTRAL NERVOUS SYSTEM in regulation of food intake, energy balance, and fat storage.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Weight Reduction Programs: Services providing counseling and activities that help overweight individuals to attain a more healthy body weight.Overweight: A status with BODY WEIGHT that is above certain standard of acceptable or desirable weight. In the scale of BODY MASS INDEX, overweight is defined as having a BMI of 25.0-29.9 kg/m2. Overweight may or may not be due to increases in body fat (ADIPOSE TISSUE), hence overweight does not equal "over fat".Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Feeding Behavior: Behavioral responses or sequences associated with eating including modes of feeding, rhythmic patterns of eating, and time intervals.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Random Allocation: A process involving chance used in therapeutic trials or other research endeavor for allocating experimental subjects, human or animal, between treatment and control groups, or among treatment groups. It may also apply to experiments on inanimate objects.Anti-Obesity Agents: Agents that increase energy expenditure and weight loss by neural and chemical regulation. Beta-adrenergic agents and serotoninergic drugs have been experimentally used in patients with non-insulin dependent diabetes mellitus (NIDDM) to treat obesity.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Dietary Fats: Fats present in food, especially in animal products such as meat, meat products, butter, ghee. They are present in lower amounts in nuts, seeds, and avocados.Body Weights and Measures: Measurements of the height, weight, length, area, etc., of the human and animal body or its parts.Infant, Newborn: An infant during the first month after birth.Anthropometry: The technique that deals with the measurement of the size, weight, and proportions of the human or other primate body.Insulin: A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Weaning: Permanent deprivation of breast milk and commencement of nourishment with other food. (From Stedman, 25th ed)Administration, Oral: The giving of drugs, chemicals, or other substances by mouth.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Animal Feed: Foodstuff used especially for domestic and laboratory animals, or livestock.Dietary Proteins: Proteins obtained from foods. They are the main source of the ESSENTIAL AMINO ACIDS.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Litter Size: The number of offspring produced at one birth by a viviparous animal.Adiposity: The amount of fat or lipid deposit at a site or an organ in the body, an indicator of body fat status.Mice, Inbred C57BLSwine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).Infant, Very Low Birth Weight: An infant whose weight at birth is less than 1500 grams (3.3 lbs), regardless of gestational age.Blood Glucose: Glucose in blood.Drinking: The consumption of liquids.Breeding: The production of offspring by selective mating or HYBRIDIZATION, GENETIC in animals or plants.Rats, Inbred F344Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Gestational Age: The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization.Lipids: A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)Ideal Body Weight: Expected weight of a healthy normal individual based on age, sex, and height. Thus, a malnourished person would weigh less than their ideal body weight.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Appetite Depressants: Agents that are used to suppress appetite.Exercise: Physical activity which is usually regular and done with the intention of improving or maintaining PHYSICAL FITNESS or HEALTH. Contrast with PHYSICAL EXERTION which is concerned largely with the physiologic and metabolic response to energy expenditure.Hypothalamus: Ventral part of the DIENCEPHALON extending from the region of the OPTIC CHIASM to the caudal border of the MAMMILLARY BODIES and forming the inferior and lateral walls of the THIRD VENTRICLE.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.Thinness: A state of insufficient flesh on the body usually defined as having a body weight less than skeletal and physical standards. Depending on age, sex, and genetic background, a BODY MASS INDEX of less than 18.5 is considered as underweight.Aging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.Diet, High-Fat: Consumption of excessive DIETARY FATS.Motor Activity: The physical activity of a human or an animal as a behavioral phenomenon.Body Constitution: The physical characteristics of the body, including the mode of performance of functions, the activity of metabolic processes, the manner and degree of reactions to stimuli, and power of resistance to the attack of pathogenic organisms.TriglyceridesSex Factors: Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Dietary Carbohydrates: Carbohydrates present in food comprising digestible sugars and starches and indigestible cellulose and other dietary fibers. The former are the major source of energy. The sugars are in beet and cane sugar, fruits, honey, sweet corn, corn syrup, milk and milk products, etc.; the starches are in cereal grains, legumes (FABACEAE), tubers, etc. (From Claudio & Lagua, Nutrition and Diet Therapy Dictionary, 3d ed, p32, p277)Lactation: The processes of milk secretion by the maternal MAMMARY GLANDS after PARTURITION. The proliferation of the mammary glandular tissue, milk synthesis, and milk expulsion or let down are regulated by the interactions of several hormones including ESTRADIOL; PROGESTERONE; PROLACTIN; and OXYTOCIN.Sexual Maturation: Achievement of full sexual capacity in animals and in humans.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Obesity, Morbid: The condition of weighing two, three, or more times the ideal weight, so called because it is associated with many serious and life-threatening disorders. In the BODY MASS INDEX, morbid obesity is defined as having a BMI greater than 40.0 kg/m2.Basal Metabolism: Heat production, or its measurement, of an organism at the lowest level of cell chemistry in an inactive, awake, fasting state. It may be determined directly by means of a calorimeter or indirectly by calculating the heat production from an analysis of the end products of oxidation within the organism or from the amount of oxygen utilized.Regression Analysis: Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.Hyperphagia: Ingestion of a greater than optimal quantity of food.Caloric Restriction: Reduction in caloric intake without reduction in adequate nutrition. In experimental animals, caloric restriction has been shown to extend lifespan and enhance other physiological variables.Food Deprivation: The withholding of food in a structured experimental situation.Appetite: Natural recurring desire for food. Alterations may be induced by APPETITE DEPRESSANTS or APPETITE STIMULANTS.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Animals, Newborn: Refers to animals in the period of time just after birth.Insulin Resistance: Diminished effectiveness of INSULIN in lowering blood sugar levels: requiring the use of 200 units or more of insulin per day to prevent HYPERGLYCEMIA or KETOSIS.Reproduction: The total process by which organisms produce offspring. (Stedman, 25th ed)Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Weight Lifting: A sport in which weights are lifted competitively or as an exercise.Mice, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations, or by parent x offspring matings carried out with certain restrictions. All animals within an inbred strain trace back to a common ancestor in the twentieth generation.No-Observed-Adverse-Effect Level: The highest dosage administered that does not produce toxic effects.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Appetite Regulation: Physiologic mechanisms which regulate or control the appetite and food intake.Lipid Metabolism: Physiological processes in biosynthesis (anabolism) and degradation (catabolism) of LIPIDS.Animal Nutritional Physiological Phenomena: Nutritional physiology of animals.Nutritional Status: State of the body in relation to the consumption and utilization of nutrients.Diabetes Mellitus, Type 2: A subclass of DIABETES MELLITUS that is not INSULIN-responsive or dependent (NIDDM). It is characterized initially by INSULIN RESISTANCE and HYPERINSULINEMIA; and eventually by GLUCOSE INTOLERANCE; HYPERGLYCEMIA; and overt diabetes. Type II diabetes mellitus is no longer considered a disease exclusively found in adults. Patients seldom develop KETOSIS but often exhibit OBESITY.Ghrelin: A 28-amino acid, acylated, orexigenic peptide that is a ligand for GROWTH HORMONE SECRETAGOGUE RECEPTORS. Ghrelin is widely expressed but primarily in the stomach in the adults. Ghrelin acts centrally to stimulate growth hormone secretion and food intake, and peripherally to regulate energy homeostasis. Its large precursor protein, known as appetite-regulating hormone or motilin-related peptide, contains ghrelin and obestatin.Sex Characteristics: Those characteristics that distinguish one SEX from the other. The primary sex characteristics are the OVARIES and TESTES and their related hormones. Secondary sex characteristics are those which are masculine or feminine but not directly related to reproduction.Phytotherapy: Use of plants or herbs to treat diseases or to alleviate pain.Sheep: Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.Mice, Obese: Mutant mice exhibiting a marked obesity coupled with overeating, hyperglycemia, hyperinsulinemia, marked insulin resistance, and infertility when in a homozygous state. They may be inbred or hybrid.Diet, Fat-Restricted: A diet that contains limited amounts of fat with less than 30% of calories from all fats and less than 10% from saturated fat. Such a diet is used in control of HYPERLIPIDEMIAS. (From Bondy et al, Metabolic Control and Disease, 8th ed, pp468-70; Dorland, 27th ed)Carcinogenicity Tests: Tests to experimentally measure the tumor-producing/cancer cell-producing potency of an agent by administering the agent (e.g., benzanthracenes) and observing the quantity of tumors or the cell transformation developed over a given period of time. The carcinogenicity value is usually measured as milligrams of agent administered per tumor developed. Though this test differs from the DNA-repair and bacterial microsome MUTAGENICITY TESTS, researchers often attempt to correlate the finding of carcinogenicity values and mutagenicity values.Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Prenatal Exposure Delayed Effects: The consequences of exposing the FETUS in utero to certain factors, such as NUTRITION PHYSIOLOGICAL PHENOMENA; PHYSIOLOGICAL STRESS; DRUGS; RADIATION; and other physical or chemical factors. These consequences are observed later in the offspring after BIRTH.Animals, Suckling: Young, unweaned mammals. Refers to nursing animals whether nourished by their biological mother, foster mother, or bottle fed.Glucose Tolerance Test: A test to determine the ability of an individual to maintain HOMEOSTASIS of BLOOD GLUCOSE. It includes measuring blood glucose levels in a fasting state, and at prescribed intervals before and after oral glucose intake (75 or 100 g) or intravenous infusion (0.5 g/kg).Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Reference Values: The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.Testis: The male gonad containing two functional parts: the SEMINIFEROUS TUBULES for the production and transport of male germ cells (SPERMATOGENESIS) and the interstitial compartment containing LEYDIG CELLS that produce ANDROGENS.Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Cachexia: General ill health, malnutrition, and weight loss, usually associated with chronic disease.Receptors, Leptin: Cell surface receptors for obesity factor (LEPTIN), a hormone secreted by the WHITE ADIPOCYTES. Upon leptin-receptor interaction, the signal is mediated through the JAK2/STAT3 pathway to regulate food intake, energy balance and fat storage.Pregnancy, Animal: The process of bearing developing young (EMBRYOS or FETUSES) in utero in non-human mammals, beginning from FERTILIZATION to BIRTH.Infant, Extremely Low Birth Weight: An infant whose weight at birth is less than 1000 grams (2.2 lbs), regardless of GESTATIONAL AGE.Anorexia Nervosa: An eating disorder that is characterized by the lack or loss of APPETITE, known as ANOREXIA. Other features include excess fear of becoming OVERWEIGHT; BODY IMAGE disturbance; significant WEIGHT LOSS; refusal to maintain minimal normal weight; and AMENORRHEA. This disorder occurs most frequently in adolescent females. (APA, Thesaurus of Psychological Index Terms, 1994)Nitrogen: An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.Gastric Bypass: Surgical procedure in which the STOMACH is transected high on the body. The resulting small proximal gastric pouch is joined to any parts of the SMALL INTESTINE by an end-to-side SURGICAL ANASTOMOSIS, depending on the amounts of intestinal surface being bypasses. This procedure is used frequently in the treatment of MORBID OBESITY by limiting the size of functional STOMACH, food intake, and food absorption.Toxicity Tests, Chronic: Experiments designed to determine the potential toxic effects of a long-term exposure to a chemical or chemicals.Pro-Opiomelanocortin: A 30-kDa protein synthesized primarily in the ANTERIOR PITUITARY GLAND and the HYPOTHALAMUS. It is also found in the skin and other peripheral tissues. Depending on species and tissues, POMC is cleaved by PROHORMONE CONVERTASES yielding various active peptides including ACTH; BETA-LIPOTROPIN; ENDORPHINS; MELANOCYTE-STIMULATING HORMONES; and others (GAMMA-LPH; CORTICOTROPIN-LIKE INTERMEDIATE LOBE PEPTIDE; N-terminal peptide of POMC or NPP).Fasting: Abstaining from all food.Nutrition Disorders: Disorders caused by nutritional imbalance, either overnutrition or undernutrition.Fetal Development: Morphological and physiological development of FETUSES.Body Surface Area: The two dimensional measure of the outer layer of the body.Crosses, Genetic: Deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent. The parent organisms must be genetically compatible and may be from different varieties or closely related species.Nutritional Requirements: The amounts of various substances in food needed by an organism to sustain healthy life.Weight-Bearing: The physical state of supporting an applied load. This often refers to the weight-bearing bones or joints that support the body's weight, especially those in the spine, hip, knee, and foot.Food, Formulated: Food and dietary formulations including elemental (chemically defined formula) diets, synthetic and semisynthetic diets, space diets, weight-reduction formulas, tube-feeding diets, complete liquid diets, and supplemental liquid and solid diets.Injections, Intravenous: Injections made into a vein for therapeutic or experimental purposes.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Growth Hormone: A polypeptide that is secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Growth hormone, also known as somatotropin, stimulates mitosis, cell differentiation and cell growth. Species-specific growth hormones have been synthesized.Glucose: A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Diabetes Mellitus, Experimental: Diabetes mellitus induced experimentally by administration of various diabetogenic agents or by PANCREATECTOMY.Carcinogens: Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.Calorimetry, Indirect: Calculation of the energy expenditure in the form of heat production of the whole body or individual organs based on respiratory gas exchange.Anorexia: The lack or loss of APPETITE accompanied by an aversion to food and the inability to eat. It is the defining characteristic of the disorder ANOREXIA NERVOSA.Infant, Premature: A human infant born before 37 weeks of GESTATION.Double-Blind Method: A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.Life Style: Typical way of life or manner of living characteristic of an individual or group. (From APA, Thesaurus of Psychological Index Terms, 8th ed)CyclobutanesMice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Toxicity Tests, Acute: Experiments designed to determine the potential toxic effects of one-time, short-term exposure to a chemical or chemicals.Agouti-Related Protein: A secreted protein of approximately 131 amino acids that is related to AGOUTI SIGNALING PROTEIN and is also an antagonist of MELANOCORTIN RECEPTOR activity. It is expressed primarily in the HYPOTHALAMUS and the ADRENAL GLAND. As a paracrine signaling molecule, AGRP is known to regulate food intake and body weight. Elevated AGRP has been associated with OBESITY.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Cross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.Animal Husbandry: The science of breeding, feeding and care of domestic animals; includes housing and nutrition.Injections, Intraperitoneal: Forceful administration into the peritoneal cavity of liquid medication, nutrient, or other fluid through a hollow needle piercing the abdominal wall.Mice, Inbred ICRRabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Body Size: The physical measurements of a body.Testosterone: A potent androgenic steroid and major product secreted by the LEYDIG CELLS of the TESTIS. Its production is stimulated by LUTEINIZING HORMONE from the PITUITARY GLAND. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to DIHYDROTESTOSTERONE or ESTRADIOL.Kinetics: The rate dynamics in chemical or physical systems.Neuropeptide Y: A 36-amino acid peptide present in many organs and in many sympathetic noradrenergic neurons. It has vasoconstrictor and natriuretic activity and regulates local blood flow, glandular secretion, and smooth muscle activity. The peptide also stimulates feeding and drinking behavior and influences secretion of pituitary hormones.Hematocrit: The volume of packed RED BLOOD CELLS in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, ANEMIA shows a low value; POLYCYTHEMIA, a high value.Half-Life: The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity.Growth: Gradual increase in the number, the size, and the complexity of cells of an individual. Growth generally results in increase in ORGAN WEIGHT; BODY WEIGHT; and BODY HEIGHT.Fetal Growth Retardation: The failure of a FETUS to attain its expected FETAL GROWTH at any GESTATIONAL AGE.Absorptiometry, Photon: A noninvasive method for assessing BODY COMPOSITION. It is based on the differential absorption of X-RAYS (or GAMMA RAYS) by different tissues such as bone, fat and other soft tissues. The source of (X-ray or gamma-ray) photon beam is generated either from radioisotopes such as GADOLINIUM 153, IODINE 125, or Americanium 241 which emit GAMMA RAYS in the appropriate range; or from an X-ray tube which produces X-RAYS in the desired range. It is primarily used for quantitating BONE MINERAL CONTENT, especially for the diagnosis of OSTEOPOROSIS, and also in measuring BONE MINERALIZATION.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.Toxicity Tests: An array of tests used to determine the toxicity of a substance to living systems. These include tests on clinical drugs, foods, and environmental pollutants.Waist Circumference: The measurement around the body at the level of the ABDOMEN and just above the hip bone. The measurement is usually taken immediately after exhalation.Milk: The white liquid secreted by the mammary glands. It contains proteins, sugar, lipids, vitamins, and minerals.Area Under Curve: A statistical means of summarizing information from a series of measurements on one individual. It is frequently used in clinical pharmacology where the AUC from serum levels can be interpreted as the total uptake of whatever has been administered. As a plot of the concentration of a drug against time, after a single dose of medicine, producing a standard shape curve, it is a means of comparing the bioavailability of the same drug made by different companies. (From Winslade, Dictionary of Clinical Research, 1992)Weights and Measures: Measuring and weighing systems and processes.Oxygen Consumption: The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)Satiation: Full gratification of a need or desire followed by a state of relative insensitivity to that particular need or desire.Least-Squares Analysis: A principle of estimation in which the estimates of a set of parameters in a statistical model are those quantities minimizing the sum of squared differences between the observed values of a dependent variable and the values predicted by the model.Injections, Subcutaneous: Forceful administration under the skin of liquid medication, nutrient, or other fluid through a hollow needle piercing the skin.Fetus: The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.Ovariectomy: The surgical removal of one or both ovaries.Insulin-Like Growth Factor I: A well-characterized basic peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like, and mitogenic activities. This growth factor has a major, but not absolute, dependence on GROWTH HORMONE. It is believed to be mainly active in adults in contrast to INSULIN-LIKE GROWTH FACTOR II, which is a major fetal growth factor.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Skinfold Thickness: The measurement of subcutaneous fat located directly beneath the skin by grasping a fold of skin and subcutaneous fat between the thumb and forefinger and pulling it away from the underlying muscle tissue. The thickness of the double layer of skin and subcutaneous tissue is then read with a caliper. The five most frequently measured sites are the upper arm, below the scapula, above the hip bone, the abdomen, and the thigh. Its application is the determination of relative fatness, of changes in physical conditioning programs, and of the percentage of body fat in desirable body weight. (From McArdle, et al., Exercise Physiology, 2d ed, p496-8)Chromatography, Gel: Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.Pregnancy Complications: Conditions or pathological processes associated with pregnancy. They can occur during or after pregnancy, and range from minor discomforts to serious diseases that require medical interventions. They include diseases in pregnant females, and pregnancies in females with diseases.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Homeostasis: The processes whereby the internal environment of an organism tends to remain balanced and stable.Fertility: The capacity to conceive or to induce conception. It may refer to either the male or female.Maternal Exposure: Exposure of the female parent, human or animal, to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals that may affect offspring. It includes pre-conception maternal exposure.Hypertension: Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more.Dietary Fiber: The remnants of plant cell walls that are resistant to digestion by the alimentary enzymes of man. It comprises various polysaccharides and lignins.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Drug Administration Schedule: Time schedule for administration of a drug in order to achieve optimum effectiveness and convenience.Adiponectin: A 30-kDa COMPLEMENT C1Q-related protein, the most abundant gene product secreted by FAT CELLS of the white ADIPOSE TISSUE. Adiponectin modulates several physiological processes, such as metabolism of GLUCOSE and FATTY ACIDS, and immune responses. Decreased plasma adiponectin levels are associated with INSULIN RESISTANCE; TYPE 2 DIABETES MELLITUS; OBESITY; and ATHEROSCLEROSIS.Bone Density: The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Food Preferences: The selection of one food over another.Peptide Hormones: Hormones synthesized from amino acids. They are distinguished from INTERCELLULAR SIGNALING PEPTIDES AND PROTEINS in that their actions are systemic.Bone and Bones: A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principle cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.Body Temperature: The measure of the level of heat of a human or animal.Tissue Distribution: Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios.Receptor, Melanocortin, Type 4: A melanocortin receptor subtype found primarily in BRAIN. It shows specificity for ALPHA-MSH; BETA-MSH and ADRENOCORTICOTROPIC HORMONE.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Maternal-Fetal Exchange: Exchange of substances between the maternal blood and the fetal blood at the PLACENTA via PLACENTAL CIRCULATION. The placental barrier excludes microbial or viral transmission.Corticosterone: An adrenocortical steroid that has modest but significant activities as a mineralocorticoid and a glucocorticoid. (From Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1437)Drug Therapy, Combination: Therapy with two or more separate preparations given for a combined effect.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Satiety Response: Behavioral response associated with the achieving of gratification.Parity: The number of offspring a female has borne. It is contrasted with GRAVIDITY, which refers to the number of pregnancies, regardless of outcome.Rats, Zucker: Two populations of Zucker rats have been cited in research--the "fatty" or obese and the lean. The "fatty" rat (Rattus norvegicus) appeared as a spontaneous mutant. The obese condition appears to be due to a single recessive gene.