Insulin Sensitivity:
Insulin sensitivity describes how sensitive the body is to the effects of insulin. Someone said to be "insulin sensitive" will require
smaller amounts of insulin in order to produce a equivilent reduction in blood glucose levels than someone who has low sensitivity. Source
Insulin Insensitivity:
"Insulin resistance is defined clinically as the inability of a known quantity of exogenous or endogenous insulin to increase glucose
uptake and utilization in an individual as much as it does in a normal population." (Lebovitz, 2001)
Ketosis:
"Athletes, clinicians, and practitioners are increasingly interested in the proposed performance and therapeutic benefits of nutritional
ketosis (NK). NK is best operationally defined as a nutritionally induced metabolic state resulting in blood β-hydroxybutyrate
concentrations of ≥0.5 mM. Most tissues readily metabolize ketone bodies (KBs), and KBs in turn regulate metabolism and signaling in both
a systemic and tissue-specific manner. During fasting, starvation, or ketogenic diets, endogenous synthesis of KBs is amplified resulting
in a state of NK." (Poff et al., 2020)
Ketone (body):
"Ketone bodies are produced by the liver and used peripherally as an energy source when glucose is not readily available. The two main
ketone bodies are acetoacetate (AcAc) and 3-β-hydroxybutyrate (3HB), while acetone is the third, and least abundant, ketone body. Ketones
are always present in the blood and their levels increase during fasting and prolonged exercise. They are also found in the blood of
neonates and pregnant women." (Laffel, 2000)
Keto-Adaptation:
"However, being in ketosis does not necessarily mean the body is optimally using [ketone bodies] for fuel. To efficiently produce and use
[ketone bodies] as an energy source, the body needs specific adaptations to accommodate the alteration in fuel preference from glucose to
[ketone bodies]. This process has been termed keto-adaptation and is thought to require dietary carbohydrate restriction for a prolonged
period of time to eventually reach metabolic adaptation, which manifests as sustained ketosis, increased rates of fat oxidation, and
concomitantly a decreased rate of carbohydrate oxidation in energy-demanding tissues such as [skeletal muscle]." (Sherrier & Hongshuai, 2019)
Metabolic Flexibility:
"Metabolic flexibility describes the ability of an organism to respond or adapt according to changes in metabolic or energy demand as well
as the prevailing conditions or activity... The more common concept of metabolic flexibility has been promulgated in the context of fuel
selection in the transition from fasting to fed states, or fasting to insulin stimulation to explain insulin resistance." (Goodpaster & Sparks, 2017)
Anabolism:
Anabolism is a general term for the synthesis of larger molecules from smaller ones, as opposed to catabolism, the breakdown of larger molecules into parts. In physiology and exercise science, these terms refer more specifically to the broad intentions of biological systems to either create, grow, and build tissues like muscle (anabolism), or breakdown, clear out, and metabolize substances (catabolism). This can be conceived of as a continual cycle, whereby catabolic processes generate the basic currency of the body, ATP, and then spend that ATP to produce anabolic effects. The two processes need to be carefully controlled, however, so that cells do not simply breakdown what have been building. Hormones play a key role in orchestrating cellular activities so as to coordinate the two principles.
Fat oxidation:
Fatty acid oxidation refers to the process of stored body fat being released, broken down, and expended as a source of energy. "Oxidation of fatty acids occurs in multiple regions of the cell within the human body... [M]etabolic conditions induce the release of fatty acids from adipose tissue... This metabolic pathway provides a large portion of the energy requirement of skeletal muscle, heart muscle, and kidneys when glycogen [stored glucose] and gluconeogenic precursors become scarce. Thus, fatty acid oxidation provides an alternative mode of high-efficiency energy production while simultaneously sparing muscles from catabolic breakdown." (Talley & Mohiuddin, 2020)
Hyper-novely:
Hyper-novelty refers to aspects of modern life which differ too greatly from the picture of our evolutionary adaptation. Behaviors and stimuli which have existed in the vast stretches of our past are ones to which we are almost certainly adapted. Negative stimuli of this sort will be likely to be matched with a system in our body to safely deal with them. For instance, oxygen is rather corrosive actually, but has been a part of the atmosphere for so long that we've turned it into an excellent fuel source. Stimuli, by contrast, which have only existed for a comparatively short period, like lead paint, year-round artificial spring-time by virtue of AC, or diets comprised of almost entirely of agricultural products made of carbohydrates.
Low-Glycemic:
Foods vary on the glycemic index based on the quantity of stimulated insulin response, with high-glycemic foods producing a large insulin response, and foods low on the glycemic index producing comparatively little insulin response.
Gluconeogenesis:
"Gluconeogenesis is the process by which the body produces glucose internally, primarily in the liver, using substrates such as pyruvate, lactic acid, glycerol, and specific amino acids classified as glucogenic." (Masood et al., 2023)