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 to be met. These criteria include being in a physically and psychologically undisturbed state and being 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) applies. 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.
Resting metabolic rate (RMR) is whole-body mammal metabolism during a time period of strict and steady resting conditions that are defined by a combination of assumptions of physiological homeostasis and biological equilibrium. RMR differs from basal metabolic rate (BMR) because BMR measurements must meet total physiological equilibrium whereas RMR conditions of measurement can be altered and defined by the contextual limitations. Therefore, BMR is measured in the elusive "perfect" steady state, whereas RMR measurement is more accessible and thus, represents most, if not all measurements or estimates of daily energy expenditure.
Thrifty phenotype refers to the correlation between low birth weight of neonates and the increased risk of developing metabolic syndromes later in life, including type 2 diabetes and cardiovascular diseases. Although early life undernutrition is thought to be the key driving factor to the hypothesis, other environmental factors have been explored for their role in susceptibility, such as physical inactivity. Genes may also play a role in susceptibility of these diseases, as they may make individuals predisposed to factors that lead to increased disease risk.
Doubly labeled water is water in which both the hydrogen and the oxygen have been partly or completely replaced with an uncommon isotope of these elements for tracing purposes.
The hypothesis of effective evolutionary time attempts to explain gradients, in particular latitudinal gradients, in species diversity. It was originally named "time hypothesis".
The thrifty gene hypothesis, or Gianfranco's hypothesis is an attempt by geneticist James V. Neel to explain why certain populations and subpopulations in the modern day are prone to diabetes mellitus type 2. He proposed the hypothesis in 1962 to resolve a fundamental problem: diabetes is clearly a very harmful medical condition, yet it is quite common, and it was already evident to Neel that it likely had a strong genetic basis. The problem is to understand how disease with a likely genetic component and with such negative effects may have been favoured by the process of natural selection. Neel suggested the resolution to this problem is that genes which predispose to diabetes were historically advantageous, but they became detrimental in the modern world. In his words they were "rendered detrimental by 'progress'". Neel's primary interest was in diabetes, but the idea was soon expanded to encompass obesity as well. Thrifty genes are genes which enable individuals to efficiently collect and process food to deposit fat during periods of food abundance in order to provide for periods of food shortage.
Jeffrey M. Friedman is a molecular geneticist at New York City's Rockefeller University and an Investigator of the Howard Hughes Medical Institute. His discovery of the hormone leptin and its role in regulating body weight has had a major role in the area of human obesity. Friedman is a physician scientist studying the genetic mechanisms that regulate body weight. His research on various aspects of obesity received national attention in late 1994, when it was announced that he and his colleagues had isolated the mouse ob gene and its human homologue. They subsequently found that injections of the encoded protein, leptin, decreases body weight of mice by reducing food intake and increasing energy expenditure. Current research is aimed at understanding the genetic basis of obesity in human and the mechanisms by which leptin transmits its weight-reducing signal.
Evolutionary physiology is the study of the biological evolution of physiological structures and processes; that is, the manner in which the functional characteristics of organisms have responded to natural selection or sexual selection or changed by random genetic drift across multiple generations during the history of a population or species. It is a sub-discipline of both physiology and evolutionary biology. Practitioners in the field come from a variety of backgrounds, including physiology, evolutionary biology, ecology, and genetics.
The "drifty gene hypothesis" was proposed by the British biologist John Speakman as an alternative to the thrifty gene hypothesis originally proposed by James V Neel in 1962.
Donald "Don" William Thomas was a Canadian university administrator and ecologist specialising in ecophysiology. At the time of his death, he was dean of the Université de Sherbrooke faculty of sciences.
Sir Stephen Patrick O'Rahilly is an Irish-British physician and scientist known for his research into the molecular pathogenesis of human obesity, insulin resistance and related metabolic and endocrine disorders.
The rate of living theory postulates that the faster an organism’s metabolism, the shorter its lifespan. First proposed by Max Rubner in 1908, the theory was based on his observation that smaller animals had faster metabolisms and shorter lifespans compared to larger animals with slower metabolisms. The theory gained further credibility through the work of Raymond Pearl, who conducted experiments on drosophila and cantaloupe seeds, which supported Rubner's initial observation. Pearl's findings were later published in his book, The Rate of Living, in 1928, in which he expounded upon Rubner's theory and demonstrated a causal relationship between the slowing of metabolism and an increase in lifespan.
Thavamani Jegajothivel Pandian, a retired professor of Madurai Kamaraj University (MKU), is an Indian geneticist and ecologist, known for his pioneering studies in bioenergetics and animal ecology. A recipient of the WorldFish Naga Award, he is a former chairman of the Task Force Committee on Aqua and Marine Biotechnology of the Department of Biotechnology of the Government of India, a former president and a fellow of The World Academy of Sciences and an elected fellow of the Indian National Science Academy, National Academy of Sciences, India, Indian Academy of Sciences and the National Academy of Agricultural Sciences. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards, in 1984, for his contributions to biological sciences.
Charles Richard Taylor was an American biologist whose career focused on animal physiology. After conducting work in east Africa, Taylor became the Charles P. Lyman professor of biology at Harvard University and was named first director the University's Concord Field Station. Taylor was elected to the American National Academy of Sciences in 1985.
The expensive tissue hypothesis (ETH) relates brain and gut size in evolution. It suggests that in order for an organism to evolve a large brain without a significant increase in basal metabolic rate, the organism must use less energy on other expensive tissues; the paper introducing the ETH suggests that in humans, this was achieved by eating an easy-to-digest diet and evolving a smaller, less energy intensive gut. The ETH has inspired many research projects to test its validity in primates and other organisms.
Anne Elisabeth Osbourn is a professor of biology and group leader at the John Innes Centre, where she investigates plant natural product biosynthesis. She discovered that in the plant genome, the genes involved with biosynthesis organise in clusters. She is also a popular science communicator, poet and is the founder of the Science, Art and Writing (SAW) Initiative. She was elected a member of the National Academy of Sciences in 2022.
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. In April 2024, he was granted the rank of doctor honoris causa from the King Juan Carlos University, Madrid.
Catherine Alison Geissler, Lady Auld is a prominent British nutritionist and author and co-author of widely recognised reference textbooks on human nutrition.
Albert Farrell Bennett is an American zoologist, physiologist, evolutionary biologist, author, and academic. He is Dean Emeritus of the School of Biological Sciences at University of California, Irvine.
