The Complete A to Z Dieting Dictionary

Following a nutritious eating plan is one of the best things you can do—not only for your weight and waistline, but also for your overall health, wellness and quality of life. But as with any important lifestyle change, there can be a bit of a learning curve, especially with so many new concepts to learn. To help ease the transition, we've prepared a quick diet dictionary that includes many of the key terms you'll likely come across on your journey.

Added sugars: Any sugars or sweeteners that are added to prepared or processed foods, such as brown sugar, cane sugar, corn syrup, glucose, malt syrup and raw sugar, among others; does not include naturally occurring sugars such as those found in fruit, milk and yogurt.
Alcohol:  Provides seven calories per gram, but with little nutritional value. Can also stimulate appetite.

Amino acids: The building blocks that make up protein.
Anorexia: An eating disorder in which the sufferer limits food consumption due to an obsessive compulsion to lose weight; can result in a dangerously low or even fatal body weight.

Artificial Sweeteners: See Non-nutritive Sweeteners
Atkins diet: A four-phase, low-carbohydrate eating plan developed by cardiologist Robert Atkins. Primarily used to promote weight loss. Initially, the plan restricts foods containing high amounts of carbohydrate and focuses on foods that contain protein and fat. Later phases reintroduce healthy carbs into the plan.
Basal Metabolic Rate: The amount of calories needed by the body to keep all involuntary processes going during a resting state, such as heartbeat, breathing, generating body heat and transmitting messages to the brain.

Body mass index (BMI): A calculation of body weight in relation to height, often used to determine whether a person is underweight, at a normal weight, overweight or obese. For healthy adults, a "normal" BMI range is 18.5 to 24.9, overweight is 25 to 29.9 and 30 or more is classified as obese.
Bulimia: An eating disorder in which the sufferer binges on food and then intentionally vomits and/or uses laxatives and diuretics in an attempt to lose weight.  
Caffeine: A mild stimulant that occurs naturally in plants such as cocoa beans, tea leaves and kola nuts. These products are used in coffee, chocolate, tea, some flavors of soft drinks and energy drinks. Excessive intake may cause "coffee jitters," anxiety, insomnia or rapid heart rate.
Calorie: Short for "kilocalorie," which is the amount of energy needed to heat a kilogram of water by one degree Celsius. The amount of calories in any given food indicates the amount of energy in that food. If you consume more calories than you burn, that results in weight gain. If you burn more than you consume, you will likely lose weight.
Carbohydrate: A macronutrient that is converted into glucose (blood sugar) during digestion, which is then used for energy. There are two groups of carbohydrates: sugars (natural and added) and complex carbohydrates (or starches), both of which provide four calories per gram. Fiber is another type of carbohydrate that is not digested and absorbed by the body.
Dietary Cholesterol: A naturally occurring substance found in many common animal-based foods, including meat, seafood, poultry, eggs and dairy products.

Blood Cholesterol: A fat-like substance produced by the body which is part of every body cell and assists with producing vitamins and hormones. There are two types of cholesterol: low-density lipoproteins (LDLs), often referred to as "bad cholesterol," and high-density lipoproteins (HDLs), also known as "good cholesterol". HDLs carry cholesterol back to the liver for disposal while LDLs carry cholesterol to tissues. Along the way, the cholesterol will build up along the walls of the arteries, which raises the risk for heart disease.
Cortisol: A hormone secreted by the adrenal gland that helps fuel the body’s "fight or flight" response. This response is activated during stress which makes stored nutrients more readily available to meet energy demands. When these hormone levels remain elevated, they can stimulate your appetite, leading to weight gain or difficulty losing weight.
Diabetes: A disease that occurs when the body does not properly process food for use as energy and blood glucose, also called blood sugar, becomes too high. Insulin, a hormone made by the pancreas, helps transport glucose into the cells, where it is used for energy. Sometimes the body does not make enough (or any) insulin or does not use insulin well. Long-term, excess blood sugar can cause heart disease, stroke, kidney damage and other dangerous effects. Regular exercise, proper nutrition and consistent blood sugar monitoring are important habits to minimize the impact of diabetes.
Electrolytes: Essential chemical substances that conduct a small electrical current in the body for many automatic processes, such as muscle function, nerve function, blood pressure regulation, tissue repair, hydration and more. Examples include sodium, potassium, calcium, chloride, phosphate and others. The body may lose a larger amount of  electrolytes with intense exercise, profuse sweating, vomiting or diarrhea, so replacement with food and drink is necessary.
Energy drink: A caffeinated beverage that may also include added sugar, vitamins, herbal supplements and other ingredients. Marketed as a beverage to enhance athletic performance, endurance and energy. The FDA continues to investigate the safety of energy drinks, particularly the effect on children and adolescents.
Fat: Dietary fat is an essential macronutrient found in food, both plant and animal. Fats are a combination of three types of fatty acids. Polyunsaturated and monounsaturated fatty acids which have been shown to enhance one’s health, while saturated fatty acids can be damaging. Fat is a source of energy with nine calories per gram.
Fiber: Dietary fiber is a component of food derived from plants that is not digested or absorbed into the bloodstream. There are two types of fiber: insoluble and soluble. Insoluble fiber promotes regular bowel habits and prevents constipation. Soluble fiber helps to lower cholesterol and regulate blood sugar levels. Fiber helps to feed the healthy bugs (probiotics) in the intestines and keeps you feeling fuller after a meal.
Gluten: The proteins found in wheat, rye, barley and triticale that give dough its elastic texture. People with the autoimmune disorder, celiac disease, cannot tolerate gluten.
Glucose: Simple sugar; the body's primary source of energy. Because it circulates in the bloodstream, it is often called blood sugar.

Glycemic Index: A categorizing system that ranks carbohydrate-containing foods (on a scale from 0 to 100) based on their effects on blood sugar levels in the body.

GMOs: Genetically modified organisms; plants, animals and microorganisms that have been chemically altered in a laboratory. Foods labeled as non-GMO are naturally occurring and have not been genetically modified.
High-density lipoprotein (HDL): Retrieves cholesterol from the body’s cells and returns it to the liver to be metabolized. Also referred to as "good" cholesterol.
Insulin: A hormone produced by the pancreas that helps to regulate blood sugar levels. Diabetes occurs when the body does not make enough (or any) insulin or does not use insulin well.  
Ketogenic diet: A very low-carbohydrate eating plan with only 5 to 10 percent of daily calories (less than 50 grams) coming from carbohydrates. Fat is increased to about 70 to 80 percent of calories, and protein intake is moderate. Normally, carbs combine with fat fragments to be used as energy. When carbs are lacking, there is an incomplete breakdown of fat that produces a by-product called ketones. These ketones accumulate in the blood and in the urine, resulting in a condition called ketosis.
Ketosis: A condition in which the body adapts to prolonged fasting or carbohydrate deprivation. When the body's energy stores are depleted, the body breaks down fat and produces ketones, which provide energy for the brain when glucose is scarce. See ketogenic diet.
Low-calorie sweeteners: See Nonnutritive Sweeteners.
Low-density lipoprotein (LDL): Transports cholesterol from the liver to be used in various cellular processes. Along the way, the cholesterol will build up along the walls of the arteries, which raises the risk factor for heart disease. Also referred to as "bad" cholesterol.
Macronutrients: Nutrients that the body uses in large amounts for energy; includes carbohydrates, fat and proteins.  
Mediterranean diet: A southern European-based nutrition plan that focuses on plant-based foods, such as vegetables, fruits, nuts, whole grains, beans, seeds and olive oil. Other foods include cheese, yogurt, some eggs, fish, poultry and only small amounts of red meat.  
Metabolism: The bodily processes needed to maintain life. Through the process of metabolism, the body turns food into the energy it needs.

Micronutrients: Vitamins and nutrients that the body uses in smaller amounts than macronutrients.

Monounsaturated Fat:  See Unsaturated Fat.

Nonnutritive Sweeteners: High-intensity sugar alternatives with little to no calories; used to sweeten foods and beverages. The FDA has approved: Acesulfame K, Aspartame, Luo han guo extract, Neotame, Saccharin, Stevia, Sucralose. Sometimes referred to as artificial sweeteners or zero-calorie sweeteners.
Nutritive Sweeteners: Contain carbohydrates and provide energy; used to sweeten foods and beverages. There are two types. Those that contain on average four calories per gram include sweeteners such as sugars, syrups, high-fructose corn syrup, honey and molasses. Those that contain on average two calories/gram are the polyols, also called sugar alcohols. Examples include sorbitol, mannitol, xylitol and erythritol.

Oils: Fats derived from plants and fish that are liquid at room temperature, including olive oil, corn oil, canola oil, soybean oil, peanut oil, avocado oil, safflower oil and sunflower oil. Some foods, such as olives, avocados, nuts and some fish are naturally high in oils.

Omega-3 Fat: A type of polyunsaturated fat that may decrease risk for heart disease, certain cancers, depression and inflammation. Found in foods such as fatty fish, flax seeds, chia seeds and walnuts.
Organic: Describes food made from organically harvested ingredients. In order to be labeled as organic, a food must be composed of at least 95 percent organically produced plants or animals.

Paleo diet: Also referred to as the "caveman diet," it focuses on meat, vegetables, fruits, nuts and roots, and eliminates sugar, grains, dairy, legumes, salt, coffee, alcohol and processed oils.

Partially hydrogenated oil: See trans fats.

Polyols: See Nutritive Sweeteners.

Polyunsaturated Fat: See Unsaturated Fat.

Protein: A macronutrient that serves the vital function of building and repairing all the tissues of the body: muscle, bone, blood and skin. Common protein sources include meat, fish, beans, eggs, dairy products, tofu, nuts and poultry. Protein is made up of amino acids and provides four calories per gram.
Raw food diet: An eating plan that only includes non-processed, plant-based foods and beverages, with at least three-quarters of them uncooked. The four types include raw vegetarians, raw vegans, raw omnivores and raw carnivores.
Recommended Dietary Allowances (RDA): Also known as Recommended Daily Allowances, this refers to the amount of any given nutrient that nearly all healthy individuals should ideally consume each day to maintain good health.
Refined grains: Grains that are not whole grains, because they have had their bran and/or germ removed during processing. Are generally low in fiber, but often enriched with iron, thiamin, niacin and riboflavin. Examples include white rice, white bread and white flour.
Saturated fat: Fats that are solid at room temperature, including meat fat such as lard, beef tallow and chicken fat; butter; coconut oil; and the fat found in cheese, yogurt, ice cream and whole milk. Excess consumption can increase the risk of heart disease by raising bad cholesterol.
Sodium: Known commonly as salt, which is composed of sodium and chloride. Sodium levels are controlled by the kidneys. Although sodium helps to ensure proper function of the muscles and nerves, high levels can lead to an increase of blood pressure. According to federal dietary guidelines, most people should consume less than 2,300 milligrams (mg) per day.
South Beach diet: A three-phase nutrition plan developed by cardiologist Arthur Agatston to help with weight loss and heart health. Focuses on lean proteins, healthy fats and unrefined, low-glycemic index carbohydrates, such as whole grains and certain fruits and vegetables. The plan avoids carbs that have a high glycemic index, which increase blood sugar more quickly.

Sugar Alcohols: See Nutritive Sweeteners.
Trans fats: There are two types of trans fats found in foods: naturally occurring and artificial. Naturally occurring trans fats are produced in the gut of some animals and foods made from these animals (e.g., milk and meat products). These contain small quantities of trans fats. Artificial trans fats (or trans fatty acids) are created during the process called hydrogenation, which changes liquid vegetable oils to a more solid form. "Partially hydrogenated oils" is the main source for trans fats. Because trans fats have been found to increase bad cholesterol, food manufacturers have developed recipes to decrease the amount found in foods such as snacks, crackers, cookies and stick margarines.
Unsaturated fats (polyunsaturated fat and monounsaturated fat): Fat that decreases the risk for cardiovascular disease by lowering bad cholesterol and triglyceride levels. Found in plant-based oils that are liquid at room temperature, such as corn, soybean and olive oils. Also found in fatty fish, such as salmon, avocados, olives, nuts, seeds and peanuts.

Vegan diet: A nutrition plan that includes only plant-based foods. Does not include any animal-based foods, including meat, eggs, dairy and sometimes honey. Often followed for nutritional/health reasons, as well in support of environmental or animal rights beliefs.
Vegetarian diet: A meatless nutrition plan. Although there are several types of vegetarians, most are in the lacto-ovo category, which does not eat animal-based foods except for dairy, eggs and sometimes honey. Some research has shown numerous health benefits of a vegetarian diet.
Whole 30 diet: A restrictive eating plan that focuses only on whole foods—including meat, seafood, eggs, vegetables, fruits, nuts and seeds—and eliminates sugar, dairy, grains, legumes and soy. At the completion of the program, foods outside the approved list can be slowly reintroduced.
Whole grains: Grains and grain products that contain the same proportion of the bran, endosperm and germ of the original grain seed (kernel).
Zone diet: A nutritional program ideally made up of 40 percent high-quality carbohydrates, 30 percent healthy fats and 30 percent proteins. The goal is to control insulin levels in order to achieve a healthy body weight.