Obesity is measured in a number of ways. The standard method is to start with your height and weight. From these measurements, the percent of ideal body weight is calculated through height/weight tables, or body mass index (BMI) is calculated through specific tables or calculations. Body fat is most often measured through a skin-fold test with calipers, and/or bioelectric impedance. Simple circumference measures of waist and hips are used to assess fat distribution in a waist-to-hip ratio.
How is obesity defined?
The National Institutes of Health defined obesity in 1985, stating that any individual 20% or more over desirable weight is obese. The medical community has further defined the condition, identifying terms for its progressing severity. Beginning in the moderately obese category, the risk of mortality and other medical complications begins to rise. Individuals who are 30% or more over desirable weight are at risk for heart disease, type 2 diabetes, and hypertension. Obesity can also refer to a body mass index (BMI) of 30+, while the phrase “overweight” can denote a lower BMI. Obesity is often defined as excessive body fat, which in some cases can be independent of weight.
How is obesity related to gender?
There is a different distribution of fat among males and females. A study involving more than 1 million men and women by the American Cancer Society has discovered the following:
Obese males, regardless of smoking habits, have a higher mortality from cancer of the colon, rectum, and prostate. Excess fat in males will be found mostly in the stomach area.
Obese females have a higher mortality from cancer of the gallbladder, biliary passages, breast (postmenopausal), uterus (including both cervix and endometrium), and ovaries. In the case of endometrial cancer, women with marked obesity showed the highest relative risk (5:4) for the obese versus the non-obese. In women, the excess fat will be mostly in the thigh or gluteal area.
Excess abdominal fat is more often related to disease than are fat deposits in the thigh or gluteal areas.
What are the causes of obesity?
Thought at one time to be a simple problem and easily solved, obesity is now recognized as a complex and often chronic condition. Disagreement and debate still prevail on almost every key issue concerning obesity. Although the basic cause of obesity is an imbalance between calorie intake and energy expenditure, why this imbalance occurs is not always clear. The tendency to gain excess weight varies from one person to another, even when food intake, physical activity, and lifestyle appear to be the same.
The underlying causes of obesity are multi-factorial in origin and include:
Increased caloric intake
High-fat diet
Physical inactivity
Reduced basal metabolic rate (BMR) – BMR is the energy required for basic bodily functions, e.g., breathing, pumping blood
Reduced dietary thermogenesis (DT) – DT is the calories burned in the digestion and absorption of food
Heredity (may affect BMR, number of fat cells, etc.)
Medical conditions/medical treatment, e.g., hypothyroidism, steroids. Less than 5% of all cases of obesity are caused by medical conditions or by treatments for medical disorders
Psychological problems
What are the risks of obesity?
Being obese can seriously affect health and longevity. Obesity has been established as a major contributor to five of the ten leading causes of death in the United States:
Coronary heart disease
Certain cancers, e.g., breast, colon
Stroke
Diabetes mellitus
Atherosclerosis
In addition to the five major diseases, obesity has been associated with an increased risk for:
Hypertension
Insulin resistance
Elevated total cholesterol and low-density lipoprotein levels (LDLs)
Reduced high-density lipoprotein levels (HDLs)
Elevated triglyceride levels
Gallbladder disease/gallstones
Digestive diseases
Sleep apnea
Gout
Osteoarthritis and degenerative joint disease of the hips and knees
