Glossary of Obesity, Physical Activity,
and Weight-Control Terms

Adipose tissue
Fat tissue in the body.

Anorexia nervosa
Dangerous condition in which victims lose interest in eating and become dangerously thin; usually associated with false beliefs about being too fat.

Bariatric surgery
Surgery on the stomach and/or intestines to help the patient with extreme obesity lose weight. Bariatric surgery is a weight-loss method used for people who have a body mass index (BMI) above 40. Surgery may also be an option for people with a BMI between 35 and 40 who have health problems like heart disease or type 2 diabetes.

Bioelectrical impedance analysis (BIA)
A way to estimate the amount of body weight that is fat and nonfat. Nonfat weight comes from bone, muscle, body water, organs, and other body tissues. BIA works by measuring how difficult it is for a harmless electrical current to move through the body. The more fat a person has, the harder it is for electricity to flow through the body. The less fat a person has, the easier it is for electricity to flow through the body. By measuring the flow of electricity, one can estimate body fat percent.

Body mass index (BMI)
A measure of body weight relative to height. BMI can be used to determine if people are at a healthy weight, overweight, or obese. To figure out BMI, use the following formula:

A BMI of 18.5 to 25 refers to a healthy weight, a BMI of 25 to 30 refers to overweight, and a BMI of 30 or higher is considered obese.

Bulimia
A disorder characterized by bingeing (episodes of eating large amounts of food) and purging (getting rid of the food by vomiting or using laxatives). Also called bulimia nervosa.

Calorie
A unit of energy in food. Foods have carbohydrates, proteins, and fats. Some beverages have alcohol. Carbohydrates have 4 calories per gram. Proteins have 4 calories per gram. Alcohol has 7 calories per gram. Fat has 9 calories per gram.

Carbohydrate
A major source of energy in the diet. There are two kinds of carbohydrates @ simple carbohydrates and complex carbohydrates. Simple carbohydrates are sugars and complex carbohydrates include both starches and fiber. Carbohydrates have 4 calories per gram. They are found naturally in foods such as breads, cereals, fruits, vegetables, and milk and dairy products. Foods such as sugar cereals, soft drinks, fruit drinks, fruit punch, lemonade, cakes, cookies, pies, ice cream, and candy are very rich in sugars.

Cholesterol
A fat-like substance that is made by the body and is found naturally in animal foods such as meat, fish, poultry, eggs, and dairy products. Foods high in cholesterol include liver and organ meats, egg yolks, and dairy fats. Cholesterol is carried in the blood. When cholesterol levels are too high, some of the cholesterol is deposited on the walls of the blood vessels. Over time, the deposits can build up causing the blood vessels to narrow and blood flow to decrease. The cholesterol in food, like saturated fat, tends to raise blood cholesterol, which increases the risk for heart disease. Total blood cholesterol levels above 240 mg/dl are considered high. Levels between 200-239 mg/dl are considered borderline high. Levels under 200 mg/dl are considered desirable.

Complex carbohydrates (starches)
Compounds composed of long chains of glucose molecules.

Diabetes mellitus
A disease that occurs when the body is not able to use blood glucose (sugar). Blood sugar levels are controlled by insulin, a hormone in the body that helps move glucose (sugar) from the blood to muscles and other tissues. Diabetes occurs when the pancreas does not make enough insulin or the body does not respond to the insulin that is made. There are two main types of diabetes mellitus: type 1 diabetes and type 2 diabetes. [See definitions]

Diet
What a person eats and drinks. Any type of eating plan.

Energy expenditure
The amount of energy, measured in calories, that a person uses. Calories are used by people to breath, circulate blood, digest food, and be physically active.

Fat
A major source of energy in the diet. All food fats have 9 calories per gram. Fat helps the body absorb fat-soluble vitamins, such as vitamins A, D, E, and K, and carotenoids. Some kinds of fats, especially saturated fats, [see definition] may cause blood cholesterol to increase and increase the risk for heart disease. Other fats, such as unsaturated fats [see definition] do not increase blood cholesterol. Fats that are in foods are combinations of monounsaturated, polyunsaturated, and saturated fatty acids.

Fiber (dietary)
Plant constituents of food that are resistant to digestion by human gastrointestinal secretions; also called roughage. “Crude fiber” is what remains after laboratory breakdown of food with acid and alkali.

Gastrointestinal surgery (to treat obesity)
See bariatric surgery.

Gestational diabetes
A type of diabetes mellitus that can occur when a woman is pregnant. In the second half of her pregnancy, a woman may have glucose (sugar) in her blood at a higher than normal level. In about 95 percent of cases, blood sugar returns to normal after the pregnancy is over. Women who develop gestational diabetes, however, are at risk for developing type 2 diabetes later in life.

Glucose
A building block for most carbohydrates. Digestion causes carbohydrates to break down into glucose. After digestion, glucose is carried in the blood and goes to body cells where it is used for energy or stored.

HDL
See high-density lipoprotein.

Healthy weight
Compared to overweight or obese, a body weight that is less likely to be linked with any weight-related health problems such as type 2 diabetes, heart disease, high blood pressure, high blood cholesterol, or others. A body mass index (BMI) of 18.5 up to 25 refers to a healthy weight, though not all individuals with a BMI in this range may be at a healthy level of body fat; they may have more body fat tissue and less muscle. A BMI of 25 up to 30 refers to overweight and a BMI of 30 or higher refers to obese.

High blood pressure
Another word for “hypertension.” Blood pressure rises and falls throughout the day. An optimal blood pressure is less than 120/80 mmHg. When blood pressure stays high, greater than or equal to 140/90 mmHg, then it is considered high blood pressure. High blood pressure increases the risk for heart disease and stroke.

High-density lipoprotein (HDL)
A form of cholesterol that circulates in the blood. Commonly called “good” cholesterol. High HDL lowers the risk of heart disease. An HDL of 60 mg/dl or greater is considered high and is protective against heart disease. An HDL less than 40 mg/dl is considered low and increases the risk for developing heart disease.

Hydrogenation
A chemical way to turn liquid fat (oil) into solid fat. This process creates a new fat called trans fatty acids. Trans fatty acids are found in margarine, shortening, and some commercial baked foods like cookies, crackers, muffins, and cereals. Eating a large amount of trans fatty acids may raise heart disease risk.

Insulin
A hormone in the body that helps move glucose (sugar) from the blood to muscles and other tissues. Insulin controls blood sugar levels.

LDL
See low-density lipoprotein.

Lipoprotein
Compounds of protein that carry fats and fat-like substances, such as cholesterol, in the blood.

Low-density lipoprotein (LDL)
A form of cholesterol that circulates in the blood. Commonly called “bad” cholesterol. High LDL increases the risk of heart disease. An LDL less than 100 mg/dl is considered optimal, 100-129 mg/dl is considered near or above optimal, 130-159 mg/dl is considered borderline high, 160-189 mg/dl is considered high, and 190 mg/dl or greater is considered very high.

Metabolism
All of the processes that occur in the body that turn the food you eat into energy your body can use.

METs (metabolic equivalents)
A measure of the intensity of physical activity. METs are multiples of the resting metabolic rate, which can be expressed in terms of total oxygen consumption or oxygen consumption per unit of body weight. One MET is the amount of oxygen consumed while a person sits quietly at rest: approximately 3.5 mL of oxygen per kilogram of body weight per minute.

Monounsaturated fat
Fats that are in foods are combinations of monounsaturated, polyunsaturated, and saturated fatty acids. Monounsaturated fat is found in canola oil, olives and olive oil, nuts, seeds, and avocados. Eating food that has more monounsaturated fat instead of saturated fat may help lower cholesterol and reduce heart disease risk. However, it has the same number of calories as other types of fat, and may still contribute to weight gain if eaten in excess.

Nutrition
(1) The process of the body using food to sustain life. (2) The study of food and diet.

Obesity
Having a high amount of body fat. People are considered obese if they have a body mass index (BMI) of 30 kg/m2 or greater.

Overweight
Being too heavy for one’s height. It is defined as a body mass index (BMI) of 25 up to 30 kg/m2. Body weight comes from fat, muscle, bone, and body water. Overweight does not always mean over fat.

Pancreas
A gland that makes enzymes that help the body break down and use nutrients in food. It also produces the hormone insulin [see definition] and releases it into the bloodstream to help the body control blood sugar levels.

Physical activity
Any form of exercise or movement. Physical activity may include planned activity such as walking, running, basketball, or other sports. Physical activity may also include other daily activities such as household chores, yard work, walking the dog, etc. It is recommended that adults get at least 30 minutes and children get at least 60 minutes of moderate physical activity most days of the week. Moderate physical activity is any activity that requires about as much energy as walking two miles in 30 minutes.

Polyunsaturated fat
A highly unsaturated fat that is liquid at room temperature. Fats that are in foods are combinations of monounsaturated, polyunsaturated, and saturated fatty acids. Polyunsaturated fats are found in greatest amounts in corn, soybean, and safflower oils, and many types of nuts. They have the same number of calories as other types of fat, and may still contribute to weight gain if eaten in excess.

Protein
One of the three types of nutrients that provides calories to the body. Protein is an essential nutrient that helps build many parts of the body, including muscle, bone, skin, and blood. Protein provides 4 calories per gram and is found in foods like meat, fish, poultry, eggs, dairy products, beans, nuts, and tofu.

Registered dietitian (R.D.)
A health professional who is a food and nutrition expert. A person who has studied diet and nutrition at an American Dietetic Association (ADA) approved college program and passed an exam to become a registered dietitian.

Saturated fat
A fat that is solid at room temperature. Fats that are in foods are combinations of monounsaturated, polyunsaturated, and saturated fatty acids. Saturated fat is found in high-fat dairy products (like cheese, whole milk, cream, butter, and regular ice cream), fatty fresh and processed meats, the skin and fat of chicken and turkey, lard, palm oil, and coconut oil. They have the same number of calories as other types of fat, and may contribute to weight gain if eaten in excess. Eating a diet high in saturated fat also raises blood cholesterol and risk of heart disease.

“Set point” theory
Theory that the body naturally gravitates toward a given weight (largely determined by genes), as if it were set by a thermostat.

Simple carbohydrate
Sugar composed of one or two sugar molecules.

Trans fatty acids
Fat composed of unsaturated fatty acids that contain one or more double bonds in which the hydrogen ions attached to the carbon atoms at the double bond are on opposite sides of the molecule. Trans fat is produced when liquid fat (oil) is turned into solid fat through a chemical process called hydrogenation (See definition). Eating a large amount of trans fatty acids can raise blood cholesterol and the risk of heart disease.

Type 1 diabetes
Previously known as “insulin-dependent diabetes mellitus,” (IDDM) or “juvenile diabetes.” Type 1 diabetes is a life-long condition in which the pancreas stops making insulin. Without insulin, the body is not able to use glucose (blood sugar) for energy. To treat the disease, a person must inject insulin, follow a diet plan, exercise daily, and test blood sugar several times a day. Type 1 diabetes usually begins before the age of 30.

Type 2 diabetes
Previously known as “noninsulin-dependent diabetes mellitus” (NIDDM) or “adult-onset diabetes.” Type 2 diabetes is the most common form of diabetes mellitus. About 90 to 95 percent of people who have diabetes have type 2 diabetes. People with type 2 diabetes produce insulin, but either do not make enough insulin or their bodies do not use the insulin they make. Most of the people who have this type of diabetes are overweight. Therefore, people with type 2 diabetes may be able to control their condition by losing weight through diet and exercise. They may also need to inject insulin or take medicine along with continuing to follow a healthy program of diet and exercise. Although type 2 diabetes commonly occurs in adults, an increasing number of children and adolescents who are overweight are also developing type 2 diabetes.

Underwater weighing
A research method for estimating body fat. A person is placed in a tank, underwater, and weighed. By comparing weight underwater with weight on land, one can get a very good measure of body fat.

Unsaturated fat
A fat that is liquid at room temperature. Vegetable oils are unsaturated fats. Unsaturated fats include polyunsaturated fats, and monounsaturated fats. They include most nuts, olives, avocados, and fatty fish, like salmon.

Very-low calorie diet (VLCD)
A person following a VLCD eats or drinks a commercially prepared formula that has 800 calories or less, instead of eating food. A VLCD can allow a person to lose weight more quickly than is usually possible with low-calorie diets, but should only be used under the supervision of a health care provider.

Waist circumference
A measurement of the waist. Fat around the waist increases the risk of obesity-related health problems. Women with a waist measurement of more than 35 inches or men with a waist measurement of more than 40 inches have a higher risk of developing obesity-related health problems, such as diabetes, high blood pressure, and heart disease.

Weight control
Achieving and maintaining a healthy weight by eating well and getting regular physical activity.

Weight-cycling
Losing and gaining weight over and over again. Commonly called “yo-yo” dieting.


Most of the definitions in this glossary were obtained from the Web site of the Weight Control Information Network (WIN), an information service of the National Institute of Diabetes and Kidney Disease (NIDDK). A few were slightly modified. The rest of the entries were added by Dr. Stephen Barrett.

This page was posted on July 26, 2007.

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