A
Acceptable Daily Intake
The amount of chemical that, if ingested daily over a lifetime, appears to be withoutappreciable effect.
Adequate Intakes (AI)
Is a value established through experimental or observational data that show a mean intake which appears to sustain a desired indicator or health when sufficient scientific evidence is not available to estimate an average requirement and no RDA exists.
Adenosine triphospate, ATP
The molecular "currency" that provides energy within cells for everything from protein synthesis to muscle contraction.
Adipose tissue
Fat, (stored body fat)
ADP
Adenosine di-phosphate, a high energy phosphate molecule involved in the production and storage of energy.  The end product of the mono-phosphate reduction of ATP.
Amino acids
Basic building blocks of protein; nonessential amino acids, essential amino acids and branched chain amino acids (BCAA).
AMP
Adenosine mono-phosphate, a phosphate molecule involved in the production of energy in the body.  The end product of the mono-phosphate reduction of ADP or the di-phosphate reduction of ATP.  Used to regenerate levels of ATP.
Antioxidant
They protect key cell components by neutralizing the damaging effects of “free radicals”.
Aspartame
Artificial, non-caloric sweetener, generic name for NutraSweet.
Aspirin
Originally a brand name, aspirin is now a generic term for acetylsalicylic acid (C 9 H 8 O 4) a common over the counter non-steroidal anti-inflammatory.
Side effects include inhibition of blood clotting (so that it may increase internal bleeding and/or the extent of bruising if used when an injury is fresh). acetaminophen (Tylenol®) may be used when a pain killer without these effects is desired, though it will not provide any anti-inflammatory effects, nor may it be substituted for aspirin in the ECA Stack.

B
Beta agonist
A beta-agonist or beta adrenoceptor agonist is a drug or chemical that partially mimics the effects of epinephrine, primarily targeting the beta adrenoceptors which accelerate heart rate and increase blood pressure (beta-1), dilate bronchial passages (beta-2), and release fatty acids from fat cells into the blood stream (all beta receptors). The most commonly encountered beta agonists are asthma drugs such as ephedrine and albuterol which target the beta-2 receptor.
Branched chain amino acids
The amino-acids L-leucine, L-isoleucine,and L-valine, so named because of their branched structure. They are a major constituent of muscle tissue and are preferentially consumed during intense exertion or dieting.
Brown fat
A type of fat cell with a greatly increased density of mitochondria and a much greater blood supply than ordinary "white" fat. Besides being able to store fat, brown fat cells can convert calories directly into heat through a process known as non-shivering thermogenisis. Brown fat is used by mammals to maintain body temperature and to expend excess calories that are consumed but not stored as fat.

C
Caffeine
An inhibitor of cAMP phoshodiesterase; it enhances alertness and potentates the effects of other stimulatory drugs by inhibiting the breakdown of cAMP, with the result that cellular processes that are activated tend to remain active longer than they would otherwise.
There is a popular myth that caffeine negates the efficacy of creatine, this has not been demonstrated.
Calorie
A unit of energy, equal to the amount of energy needed to heat one gram of water one degree Celsius. In common usage, the "calories" most often refer to kilocalories (also known as Kcal or "food calories") which are really 1000 calories.
Canthaxanthin
A carotenoid related to beta carotene used as a red food coloring. When taken in (relatively) large quantities, it imparts a reddish-orange tone to the skin leading to its use as a tanning aid. It is non-toxic and has some antioxidant activity, but prolonged use at high doses has been known to cause crystals to form inside the eye.
Capsicum
The active chemical in hot peppers.
Carbohydrate
Digestible food components such as starches and sugars that are composed of carbon, hydrogen, and oxygen, but not nitrogen. Carbohydrates are the main constituent of most vegetables and fruits, provide four calories per gram, and are present only in small quantities in animal products.
Carb-up
After any period of carbohydrate depletion, particularly as part of a cyclic ketogenic diet, the consumption of large quantities of carbohydrates with the intent of saturating muscle glycogen stores.
Cholesterol
An alcohol steroid found in animal fats; Fat-like substance implicated in the narrowing of the arteries in atherosclerosis.  Found in dietary products and blood.
Conjugated linoleic acid (CLA)
A particular structural variant of linoleic acid (a common unsaturated fatty acid). Several studies exist supporting a potential health benefit of conjugated linoleic acid (CLA). No studies suggest that it will aid muscle growth or fat loss.
Creatine
Naturally occurring in muscle tissue, creatine functions as a secondary reservoir for short-term energy to be drawn upon when ATP (adenosine triphosphate) stores--the energy storage molecule that drives muscular contraction--are depleted. Supplemental creatine monohydrate added to the diet will increase the concentration of creatine phosphate within muscle tissue which may increase one's ability to perform brief, high-intensity exercise.

D
DHEA
Dehydroepiandrosterone or dehydroandrosterone that is derived from human urine and other sources.
Diabetes
The body’s inability to produce sufficient insulin or use it effectively to metabolism sugar.  Type 1 or Type 2.
Diuretic
A drug that increases the rate at which water is excreted through the kidneys.
DNA
Deoxyribonucleic Acid.  This is the molecule that carries the genetic information for most living systems.
DRI
Dietary Reference Intake is a generic term used to refer to group of reference values designed to reflect latest understanding about nutrient requirements based on optimizing health in individuals and groups.
DRV
The second set of numbers you find on the label are four nutrients and food components that traditionally do not have an RDA, such as fat and fiber.

E
ECA, ECA stack
Ephedrine, Caffeine, and Aspirin, a popular and effective thermogenic combination of drugs used for weight loss and energy. Ephedrine is a stimulant that acts to increase alertness, energy, and body temperature, thus increasing caloric expenditure.
Caffeine inhibits the body's natural tendency to counteract the stimulant effects of ephedrine, so that the two of them used together increase caloric expenditures more than the sum of the increases caused by each one used individually. The most common dosage is 200mg of caffeine taken with 20mg of ephedrine (= 25mg of ephedrine hydrochloride) three times per day, the third dose being taken not later than dinnertime. Caffeine and ephedrine act as appetite suppressants, which has weight-loss benefits as well.
60mg of aspirin (about a quarter of a standard aspirin tablet) is often added to the stack, but studies have not shown conclusively that ECA is more effective for weight loss than ephedrine and caffeine without aspirin.
Please note that ephedrine and caffeine also have a diuretic effect, so some weight loss will be due to a loss of water and not fat.
Electrolytes
Minerals such as sodium, potassium, magnesium, and calcium used by cells in the creation and elimination of membrane potentials used to propagate nerve impulses and muscular contraction.
Enzyme
A protein catalyst; enzymes are involved in digestion and both the synthesis and breakdown of proteins, hormones, and other substances in the body.
Ephedra
An herb also known as Ma Huang and "Mormon Tea" containing ephedrine and pseudoephedrine.
Ephedrine
A common Beta agonist used to relieve the symptoms of asthma; it dilates bronchial passages and is also a stimulant.  Has been used for performance enhancing and fat lose.  Ephedrine use is banned from collegiate and professional sports. 
Essential
Nutrient that cannot be manufactured by the body and must be consumed in food.
Essential amino acids
Amino acids which cannot be synthesized by the body from other amino acids and, thus, must be present in the diet: leucine, isoleucine, lysine, methionine, phenylalanine, tryptophan, and valine.
Essential fatty acids
Unsaturated fatty acids which cannot be synthesized by the body and are used as the starting point for the biosynthesis of necessary metabolic and hormonal chemicals.

F
Fat
Digestible food components such as butter, lard, and oils composed of fatty acids. All kinds of fats provide nine calories per gram.
Fat-Soluble vitamins
Vitamins soluble in fat, not water.  Fat soluble vitamins include A, D, E, and K.  They pose the greatest risk for reaching toxic levels from mega-dosing.
Fiber
An indigestible component of food, chemically classified as carbohydrates (and may be included in the total carbohydrate content listed on food labels), found primarily in unprocessed vegetables, nuts, grains, and fruits. Fiber does not provide calories but offers significant health benefits as a component of the diet.  Both soluble and insoluble fiber promotes many positive health benefits.
Flax seed oil
An oil rich in omega-3 polyunsaturated fatty acids; because of the high polyunsaturated fatty acid content, it should be kept refrigerated and even then has a limited shelf life.
Folic Acid
Folic acid, folate, folacin, all form a group of compounds functionally involved in amino acid metabolism and nucleic acid synthesis.
Food and Drug Administration
The food and Drug Administration is part of the Public Health Service of the U.S. Department of Health and Human Services.
Food Guide Pyramid
The food Guide Pyramid is a graphic design used to communicate the recommended daily food choices contained in the Dietary Guidelines for Americans.
Free Radicals
Free radicals are byproducts of cell metabolism.  They form when oxygen is metabolized or burned by the body.  They travel through cells, disrupting the structure of other molecules, causing cellular damage.
Fructose
Also known as "fruit sugar" even though it is found in many foods besides fruit and it is not the majority of the sugar content in most fruits. Fructose also forms half of the sucrose (ordinary table sugar) molecule. Approximately 50 grams of fructose per day can be metabolized by the liver into glucose; amounts consumed beyond that will be converted into triglycerides using an alternate pathway.

G
Glucose
Also known as dextrose , a simple sugar which is the main form of carbohydrate transported through the bloodstream to be used for fuel by cells.
Glycemic index
Glycemic Index (GI) is a rating system for carbohydrates that deals with how quickly the sugar enters the blood stream and the extent of the insulin response following that entry. GIs were initially established to help diabetics regulate insulin levels following meals. Those carbohydrate sources that have low GIs generally enter the blood stream slower or cause a smaller insulin response. This can be beneficial for those trying to lose fat as well as those who are diabetic.  
Glycogen
A type of starch synthesized from glucose for intracellular storage. The primary glycogen stores are in the liver and in the muscles; liver glycogen stores will be broken down to glucose and released into the bloodstream when blood sugar levels are low, whereas this does not happen with muscle glycogen stores which will be used only to provide fuel for the muscles themselves.
Note that way that glycogen is stored in the body requires four grams of water to be stored for each gram of glycogen. The combined weight and volume of muscle glycogen stores accounts for a significant part of total muscular size. The depletion of these glycogen stores (and the release of the accompanying water) is what accounts for the rapid weight loss experienced in the first few days of ketogenic and other reduced-carbohydrate diets.
Guarana
An herb containing significant amounts of caffeine.

H
Health
Is the general term used to describe total condition of the body and mind.

HydroxyMethylButyrate, HMB
A metabolite of the branched-chain amino acid leucine, HMB is also available in supplement form. Some studies have shown increased growth in cattle given HMB, but evidence of any value for increasing human muscle growth and athletic performance is limited.
Hydrogenated fat; trans fat
Occurs in the manufacturing phase of margarine and other vegetable shortenings; trans fat do not typically occur in the environment naturally and have been linked to major health concerns.

I
Insulin
A hormone that promotes the uptake of nutrients (most notably glucose,
Insulin resistance
A reduced sensitivity to insulin, meaning that more insulin must be released to cause a given amount of nutrients uptake into the body's cells. Note that the down regulation of insulin sensitivity is likely to be more extreme in lean tissue than adipose tissue , so that persons who have developed a high degree of insulin resistance are likely to preferentially store nutrients as fat rather than use them for tissue growth and repair.
type-II (adult onset) diabetes is an extreme form of insulin resistance.

J

K
Krebs cycle
A sequence of chemical reactions occurring within the mitochondria of living cells in which acetic acid (produced from foods) is oxidized to produce high-energy phosphate bonds (converting ADP to ATP ) to be used to power the body's other metabolic processes. Also known as the citric acid cycle.

L
Lipid
Fat (usually when in the body rather than in food); a general term used for several different compounds, which include both solid fats and liquid oils; the three major classes of lipid’s are triglycerides, phospholipids, and sterols
Low-carb.
A genre of diet characterized by the reduction in carbohydrate intake, often but not necessarily to a ketogenic degree.

M
Macronutrient
A nutrient (such as protein, carbohydrate, or fat) used in large quantities to provide energy for life and/or raw materials for synthesizing or repairing tissue
Mcg or ug
Microgram
Meal Replacement Powder
Instant milkshakes with added protein. Used to replace or be combined with nutrition from whole foods.
Medium chain triglycerides 
Known as the "fatless fat", these fat molecules are easily mobilized in the bloodstream to provide long-lasting energy, rather than being stored as fat. They also help limit the conversion of excess carbohydrates into fat.
Metabolism
The body’s ability to absorb and digest food to be converted into mechanical energy.
Mg
Milligram
Micronutrient
A nutrient (such as a vitamin or mineral) needed in small quantities for the normal functioning of the body.
Mineral
Mostly metallic elements collectively called minerals, minerals serve constituents of enzymes, hormones, and vitamins; they combine with other chemicals or exist singularly; they are needed in small amounts
Monounsaturated fats
Monounsaturated fats are fatty acids with one double-bonded carbon in the molecule.
MRP
See Meal Replacement Powder

N
NutraSweet
Artificial, non-caloric sweetener, brand name for aspartam

O
Omega-3 polyunsaturated fatty acids
Unsaturated fatty acids with the double bond at the third carbon position. Omega-3 fatty acids include alpha-linolenic (found in large quantities in flax seed oil ) and eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids (found in fish oils).

P
Peptide
A short chain of amino acids.

Polyunsaturated fats
Fat containing two or more double bonds along the main carbon chain.
Potentate
To increase the effect(s) of, usually used in reference to the effects of a drug.
Protein
Digestible food components containing nitrogen composed of amino acids; protein is essential for tissue repair and growth and provides four calories per gram.
Pseudoephedrine
An isomer of ephedrine that is a far weaker stimulant and bronchodilator and is used primarily as a decongestant.
It is not a suitable substitute for ephedrine in the ECA stack

Q

R
RDA
The Recommended Dietary Allowances is the dietary intake level that is sufficient to meet the nutrient requirements of nearly all individuals in a specific age and gender group,

RDI

Reference Daily Intakes; The values listed on the food labels form nutrients reflect average allowances based on the RDA
Ribose
A pentose sugar, occurring as a component of riboflavin, nucleotides, and nucleic acids.

S
Saturated fats
Fats comprised of fatty acids in which all possible bond positions along the carbon backbone are filled with hydrogens. Saturated fats are solid at room temperature, stable at high temperatures, and have long shelf-lives. While this makes them excellent for frying, especially deep frying, they have no nutritional or metabolic functions beyond providing calories. 
Sorbitol
A naturally occurring sugar alcohol commonly used in "sugar-free" products. Its caloric content is similar to ordinary sugar, but it is absorbed more slowly, reducing its glycemic index, but often causing gastric discomfort, gas, and diarrhea when consumed in large quantities because intestinal bacteria have ample time to begin breaking it down before it is absorbed.
After being absorbed into the bloodstream, sorbitol is converted into fructose.
Stack, supplement or drug
Common term used to describe the process of combining multiple supplements or drugs for an increased effect.
Sublingual
Absorbed into the bloodstream through the skin under the tongue, an area with especially thin skin and a rich blood supply. Bypasses the liver and the rest of the digestive system and exposure to all the acids and enzymes involved.
Sugar
Either a generic term for a short-chain carbohydrate or a specific term for sucrose (table sugar). Monosaccharide sugars (simple sugars) include fructose (fruit sugar), glucose (dextrose, grape sugar, corn sugar), galactose. Disaccharide sugars (sugars made from two monosaccharide bonded together) include sucrose (table sugar, cane sugar, or beet sugar), maltose, lactose (milk sugar).
* note that % glucose and % fructose values include the glucose and fructose fractions of disaccharides sucrose (one fructose molecule and one glucose molecule bonded together) and maltose (two glucose molecules bonded together)
Sugar alcohol
Structurally, a hydrogenated sugar molecule with taste and physical properties similar to sugar, but more slowly absorbed by the body. Sugar alcohols include xylitol, mannitol, sorbitol, and malitol, and do appear naturally in some foods. Used in "sugar free" products because of their slow absorbtion rate (important for diabetics and those with hypoglycemia), they still contain calories and count as carbohydrates

T
Targeted ketogenic diet, TKD
A ketogenic diet in which a small quantity of high glycemic-index carbohydrates are taken immediately before and/or following a workout to partially replenish muscle glycogen supplies.
Trans-fatty acids
Unsaturated fatty acids that have a "z" shape caused by unsaturated bonds being on alternate sides of the molecule. Naturally formed unsaturated fatty acids are normally in the "cis" configuration, with the unsaturated bonds on the same side of the carbon chain. The trans- configuration is typically produced by the partial hydrogenation of polyunsaturated fatty acids which is done to increase shelf life, heat stability, and thickness.
Tribulus terresteris
Herb or herbal extract supplying protodioscin, which has been shown to increase erectile response in rabbits. It has not, however, been shown to increase total or free testosterone levels and studies on strength and body composition on resistance-trained males have shown reduced gains in the tribulus group compared with the placebo group.
Triglyceride
Chemical name for fat usually used when referring to fats in the bloodstream rather than in food. The name comes from the three fatty acid chains that together with the glycerol "backbone" make up the molecule.

U
Unsaturated fats
Fats containing fatty acids with some carbon-carbon double bonds. Saturated fats have all possible positions that could be occupied by a hydrogen atom filled, leaving no double bonds in the carbon chain.

V
Vegan
Vegetarians who avoid all animal-derived foods.
Vitamin
A micronutrient that is necessary for the continued normal functioning of the body.
Viagra
Brand name of sildenafil, a selective type 5 cGMP phosphodiesterase inhibitor, which enhances nitric-oxide-dependent vasodilation in the corpus cavernosum, thus increasing erectile response in males suffering from impotence; note that Viagra does not initiate or increase sexual drive or desire or affect testosterone levels.

W
Water-soluble vitamins
Vitamins that are soluble in water, not fat.  Many are involved in the reactions supporting energy metabolism.  These vitamins are not normally stored in the body in appreciable amounts and are normally excreted in the urine.

X

Xenobiotics
Synthetic chemicals believed to be resistant to environmental degradation.

Y
Yohimbe, yohimbine
Yohimbe (Corynanthe yohimbe) is an herb derived from the bark of the yohimbe tree found primarily in the West African nations of Cameroon, Gabon, and Zaire. The major active constituent of the bark is yohimbine. In prescription doses, the active ingredient is yohimbine hydrochloride.

Z