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Obesity is the most prevalent nutritional problem in the United States today and is a major factor in the pathogenesis of hypertension, diabetes mellitus, hypercholesterolemia, heart disease, and such common forms of cancer as breast cancer, prostate cancer, uterine cancer and colon cancer. According to the 1998 National Heart Lung and Blood Institute guidelines for diagnosing overweight and obesity, one of every two Americans is overweight or obese. In some ethnic groups, one of every two women is obese, while in the general population one of three adults is obese. One of every three women is on a diet at any time, and the American public spends billions of dollars on fad diets and unproven remedies for weight reduction and nutritional health each year.
Why has obesity been a blind spot for American medicine until recent years? Our medical schools are based on allopathy, the use of drugs and surgery to treat disease. Prevention and nutrition have only recently been introduced into the curriculum of a minority of American medical schools, but form the basis of medical education in much of the rest of the world. Asian medicine, which was not influenced as much by the English system of the Royal College of Barbers and Surgeons, includes nutrition, food herbs, and herbal medicines as an integral part of health maintenance and treatment. Most American physicians today ignore the problem of obesity. They will treat patients for high blood pressure, high cholesterol or diabetes with drugs, without addressing the underlying nutritional etiology of these diseases. When asked why this is so, they respond with the following :
On January 1, 1998, The New England Journal of Medicine, a widely quoted and respected journal ran an editorial entitled, " Weight Loss: An Ill-Fated New Yearís Resolution" in which they asserted that weight loss was not achievable, the treatments were more risky than the disease itself, and even if you lost weight you wouldnít live longer. In fact, subsequent studies have shown that the morbidities associated with getting old occur over a shorter period of time in health conscious individuals, saving money for the health care system while improving quality of life for the elderly.
In fact, the pharmaceutical industry has developed its own diets and promulgated diets through organizations such as the American Heart Association, the American Cancer Society, and the American Diabetes Association that fail to deal with the nutrition-related chronic diseases related to obesity. In dealing with individuals with obesity, the dietary guidelines promulgated for populations must be individually tailored to meet the needs of the person dealing with the problem. The California Cuisine Pyramid was designed by the UCLA Center for Human Nutrition to move ahead from the late 1980ís pyramids to one designed for chronic disease prevention. The rationale for this pyramid will be developed later in the course.
After finishing this section of the course you should:
1) Understand the definition and causes of obesity.
Understand the impact of excess fat on endocrine/metabolic processes
Obesity is defined as excess body fat. Increased body weight does not always equate to increased body fat. For example, a professional football player could weigh 260 pounds and be six feet tall with no excess fat, just increased lean body mass.
One can assess body fat in several ways:
Body weight for height can be used in average people
Rule of thumb:
Life insurance tables can also be used to assess ideal weight based on minimum mortality. The most famous tables are the Metropolitan Life Insurance Tables of 1959 and 1983. These relate mortality from all causes to body weight at the time of life insurance medical examination. By this classification degrees of obesity are:
Prevalence of obesity from the USDA National Health and Nutrition Examination Survey (NHANES) by these standards is as follows:
Body Mass Index is used to estimate excess fat
Body Mass Index = Wt.(in kg.) / Ht.2(in meters2)
Overall morbidity and mortality increases exponentially at a calculated BMI of greater than 30. At any given BMI women have a greater percent body fat than men, so other methods are also needed to assess body fat clinically.
Other Methods of Estimating Body Fat
Total body potassium
Abnormal Fat Distribution
Male or Android Fat Cells
Female or Gynoid Fat
Garrow and Webster found that the regression of fat4/ H2 on weight/ H2 was 0.955 for women and 0.943 for men. Prediction equations were developed based on these findings. Fat in kg can be calculated from weight and height as follows:
These authors found that the errors were approximately 4.2 kg and 5.8 kg of fat for men and women respectively. This error is of similar magnitude to that found with the densitometry, total body water by dilution, and total body potassium counting. However, it was recognized in the original publication that this formula was not suitable for athletes or the elderly where there would be significant variations in lean body mass.
Lecture 1:Introduction to Nutrition in Western Civilization
Lecture 2: Dietary Macronutrients, Body Fat, and Blood Lipids
Lecture 3:Digestion and Absorption of Macronutrients
Lecture 4:Basic Principles of Nutrient Metabolism
Lecture 6:Fuel Utilization During Exercise
Lecture 7:Biochemistry of Oxidant Stress in Health and Disease Antioxidants
Lecture 8:Nutrition for the 21st Century