Thermogenic means tending to produce heat, and the term is commonly applied to drugs which increase heat through metabolic stimulation, [1] or to microorganisms which create heat within organic waste. Approximately all enzymatic reaction in the human body is thermogenic, which gives rise to the basal metabolic rate. [2]
In bodybuilding, athletes wishing to lose fat purportedly use thermogenics to increase their basal metabolic rate, thereby increasing their energy expenditure. Caffeine and ephedrine are commonly used for this purpose. 2,4-Dinitrophenol (DNP) is a very strong thermogenic drug used for fat loss; it will give a dose-dependent increase in body temperature, to the point where it can induce death by hyperthermia. It works as a mitochondrial oxidative phosphorylation uncoupler, disrupting the mitochondrial electron transport chain. This stops the mitochondria from producing adenosine triphosphate, releasing energy as heat.
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Metabolic syndrome is a clustering of at least three of the five following medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL).
Abdominal obesity, also known as central obesity and truncal obesity, is a condition when excessive abdominal fat around the stomach and abdomen has built up to the extent that it is likely to have a negative impact on health. Central obesity has been strongly linked to cardiovascular disease, Alzheimer's disease, and other metabolic and vascular diseases.
Brown adipose tissue (BAT) or brown fat makes up the adipose organ together with white adipose tissue. Brown adipose tissue is found in almost all mammals.
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation. The internal thermoregulation process is one aspect of homeostasis: a state of dynamic stability in an organism's internal conditions, maintained far from thermal equilibrium with its environment. If the body is unable to maintain a normal temperature and it increases significantly above normal, a condition known as hyperthermia occurs. Humans may also experience lethal hyperthermia when the wet bulb temperature is sustained above 35 °C (95 °F) for six hours. The opposite condition, when body temperature decreases below normal levels, is known as hypothermia. It results when the homeostatic control mechanisms of heat within the body malfunction, causing the body to lose heat faster than producing it. Normal body temperature is around 37 °C (99 °F), and hypothermia sets in when the core body temperature gets lower than 35 °C (95 °F). Usually caused by prolonged exposure to cold temperatures, hypothermia is usually treated by methods that attempt to raise the body temperature back to a normal range.
Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular endothelial cells and a variety of immune cells such as adipose tissue macrophages. Adipose tissue is derived from preadipocytes. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Far from being hormonally inert, adipose tissue has, in recent years, been recognized as a major endocrine organ, as it produces hormones such as leptin, estrogen, resistin, and cytokine. The two types of adipose tissue are white adipose tissue (WAT), which stores energy, and brown adipose tissue (BAT), which generates body heat. The formation of adipose tissue appears to be controlled in part by the adipose gene. Adipose tissue – more specifically brown adipose tissue – was first identified by the Swiss naturalist Conrad Gessner in 1551.
Thermogenin is an uncoupling protein found in the mitochondria of brown adipose tissue (BAT). It is used to generate heat by non-shivering thermogenesis, and makes a quantitatively important contribution to countering heat loss in babies which would otherwise occur due to their high surface area-volume ratio.
Thermogenesis is the process of heat production in organisms. It occurs in all warm-blooded animals, and also in a few species of thermogenic plants such as the Eastern skunk cabbage, the Voodoo lily, and the giant water lilies of the genus Victoria. The lodgepole pine dwarf mistletoe, Arceuthobium americanum disperses its seeds explosively through thermogenesis.
Basal metabolic rate (BMR) is the rate of energy expenditure per unit time by endothermic animals at rest. It is reported in energy units per unit time ranging from watt (joule/second) to ml O2/min or joule per hour per kg body mass J/(h·kg). Proper measurement requires a strict set of criteria be met. These criteria include being in a physically and psychologically undisturbed state, in a thermally neutral environment, while in the post-absorptive state (i.e., not actively digesting food). In bradymetabolic animals, such as fish and reptiles, the equivalent term standard metabolic rate (SMR) is used. It follows the same criteria as BMR, but requires the documentation of the temperature at which the metabolic rate was measured. This makes BMR a variant of standard metabolic rate measurement that excludes the temperature data, a practice that has led to problems in defining "standard" rates of metabolism for many mammals.
2,4-Dinitrophenol (2,4-DNP or simply DNP) is an organic compound with the formula HOC6H3(NO2)2. It is a yellow, crystalline solid that has a sweet, musty odor. It sublimes, is volatile with steam, and is soluble in most organic solvents as well as aqueous alkaline solutions. When in a dry form, it is a high explosive and has an instantaneous explosion hazard. It is a precursor to other chemicals and is biochemically active, inhibiting adenosine triphosphate (ATP) production in cells with mitochondria. Its use as a dieting aid has been identified with severe side-effects, including a number of deaths.
Weight gain is an increase in body weight. This can involve an increase in muscle mass, fat deposits, excess fluids such as water or other factors. Weight gain can be a symptom of a serious medical condition.
The respiratory quotient, is a dimensionless number used in calculations of basal metabolic rate (BMR) when estimated from carbon dioxide production. It is calculated from the ratio of carbon dioxide produced by the body to oxygen consumed by the body. Such measurements, like measurements of oxygen uptake, are forms of indirect calorimetry. It is measured using a respirometer. The Respiratory Quotient value indicates which macronutrients are being metabolized, as different energy pathways are used for fats, carbohydrates, and proteins. If metabolism consists solely of lipids, the Respiratory Quotient is 0.7, for proteins it is 0.8, and for carbohydrates it is 1.0. Most of the time, however, energy consumption is composed of both fats and carbohydrates. The approximate respiratory quotient of a mixed diet is 0.8. Some of the other factors that may affect the respiratory quotient are energy balance, circulating insulin, and insulin sensitivity.
An uncoupling protein (UCP) is a mitochondrial inner membrane protein that is a regulated proton channel or transporter. An uncoupling protein is thus capable of dissipating the proton gradient generated by NADH-powered pumping of protons from the mitochondrial matrix to the mitochondrial intermembrane space. The energy lost in dissipating the proton gradient via UCPs is not used to do biochemical work. Instead, heat is generated. This is what links UCP to thermogenesis. However, not all kinds of UCPs are related to thermogenesis. Although UCP2 and UCP3 are closely related to UCP1, UCP2 and UCP3 do not affect thermoregulatory abilities of vertebrates. UCPs are positioned in the same membrane as the ATP synthase, which is also a proton channel. The two proteins thus work in parallel with one generating heat and the other generating ATP from ADP and inorganic phosphate, the last step in oxidative phosphorylation. Mitochondria respiration is coupled to ATP synthesis but is regulated by UCPs.
The diet-induced obesity model is an animal model used to study obesity using animals that have obesity caused by being fed high-fat or high-density diets. It is intended to mimic the most common cause of obesity in humans. Typically mice, rats, dogs, or non-human primates are used in these models. These animals can then be used to study in vivo obesity, obesity's comorbidities, and other related diseases. Users of such models must take into account the duration and type of diet as well as the environmental conditions and age of the animals, as each may promote different bodyweights, fat percentages, or behaviors.
Adiposopathy is defined as pathologic adipocyte and adipose tissue anatomic & functional disturbances, promoted by positive caloric balance, in genetically and environmentally susceptible individuals. The ensuing pathogenic endocrine and immune responses may directly promote cardiovascular disease, and may also cause or worsen among the most common metabolic disease encountered in developed countries. Because many of these metabolic diseases are major cardiovascular disease risk factors, adiposopathy also indirectly increases CVD risk, and is an important contributor to the metabolic syndrome.
Obesity in pets occurs when excessive adipose tissue accumulates in the body, and is generally defined as occurring when an animal's body weight is at least 20% greater than its optimal body weight. Obesity is associated with metabolic and hormonal changes.
In biology, energy homeostasis, or the homeostatic control of energy balance, is a biological process that involves the coordinated homeostatic regulation of food intake and energy expenditure. The human brain, particularly the hypothalamus, plays a central role in regulating energy homeostasis and generating the sense of hunger by integrating a number of biochemical signals that transmit information about energy balance. Fifty percent of the energy from glucose metabolism is immediately converted to heat.
The plateau principle is a mathematical model or scientific law originally developed to explain the time course of drug action (pharmacokinetics). The principle has wide applicability in pharmacology, physiology, nutrition, biochemistry, and system dynamics. It applies whenever a drug or nutrient is infused or ingested at a relatively constant rate and when a constant fraction is eliminated during each time interval. Under these conditions, any change in the rate of infusion leads to an exponential increase or decrease until a new level is achieved. This behavior is also called an approach to steady state because rather than causing an indefinite increase or decrease, a natural balance is achieved when the rate of infusion or production is balanced by the rate of loss.
Obesity classification is a ranking of obesity, the medical condition in which excess body fat has accumulated to the extent that it has an adverse effect on health. The World Health Organization (WHO) classifies obesity by body mass index (BMI). BMI is further evaluated in terms of fat distribution via the waist–hip ratio and total cardiovascular risk factors. In children, a healthy weight varies with age and sex, and obesity determination is in relation to a historical normal group.
Weight management is the phrase used to describe both the techniques and underlying physiological processes that contribute to a person's ability to attain and maintain a certain weight. Most weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. Moreover, weight management involves developing meaningful ways to track weight over time and to identify ideal body weights for different individuals.
Antonio Vidal-Puig is a Spanish medical doctor and scientist who works as a Professor of Molecular Nutrition and Metabolism at the University of Cambridge (UK), best known for advancing the concept that pharmacological targeting of brown fat may serve to treat overweight and obesity in affected individuals, as well as for introducing the concept of adipose tissue expandability as an important factor in the pathogenesis of insulin resistance in the context of positive energy balance. His published work focuses on areas such as adipose tissue metabolism and lipotoxicity, regulation of insulin secretion, and the pathophysiology of metabolic syndrome, obesity, and type 2 diabetes.