Nutrition 101Natural RemediesWeioht ManagementPhysician Education
Vitamins and MineralsNutrition and AgingNutrition and DiseaseResearch
HomeSite Search
Weight Management Home


1200 Calorie

1500 Calorie

What is a
Food Portion?


Body Mass Index (BMI)/Protein

Trigger Foods


ScaleCauses and Metabolic Consequences of Obesity

Obesity is defined as excess body fat, and results from a gene-environment interaction. The deposition of fat when there is excess energy intake relative to expenditure is entirely normal. While man is well-adapted to starvation as the result of thousands of years of exposure to irregular food supplies, he is poorly adapted to overnutrition. In fact, man has only had a surplus of food in the past 100 years. Therefore, it is not surprising that there has not been an adaptation to overnutrition. The modern high fat diet combined with physical inactivity has resulted in an epidemic of obesity and overweight affecting one of every two Americans. There are clearly individual differences in metabolism and energy efficiency which are in part inherited. Therefore, while genetics determines the potential for obesity, diet, exercise, and lifestyle determine whether and to what extent obesity develops.

The metabolic consequences of obesity are highly dependent on fat distribution. Increased abdominal fat accumulation is associated with insulin resistance. While this fat distribution is called android obesity, it can occur both in men and women. However, lower body, or gynoid, obesity occurs only in women and castrate men. Abdominal adipocytes release free fatty acids more readily under the influence of catecholamines, and these fatty acids in the portal circulation may engender insulin resistance. Women with abdominal obesity have higher levels of male hormones than women with lower body fat or gynoid obesity. In fact, visceral obesity is associated with hyperinsulinemia, hypertriglyceridemia, glucose intolerance, hypertension, and common forms of cancer. In addition, polycystic ovarian syndrome, characterized by insulin resistance, dysmenorrhea, hirsutism and obesity, is more common in women with upper body obesity. Infertility is also more common in overweight women.

The health consequences of obesity include some of the most common chronic diseases in our society. Obesity is an independent risk factor for heart disease, the most common killer disease in our country. Non-insulin dependent diabetes mellitus, hypertension and stroke, hyperlipidemia, osteoarthritis, and sleep apnea are all more common in obese individuals. Weight loss of only 20 pounds can be associated with marked reductions in the risk of these chronic diseases. Conversely, adult weight gain is associated with increased risk of breast cancer in postmenopausal women. Psychiatric disorders are no more common in obese individuals, but the incidence of mild depression and anxiety is increased in obese compared to non-obese individuals. It has not been determined how much of the increased risk is secondary to the negative reaction of our society to obese individuals versus endogenous differences associated with obesity. .

Obesity is the most common nutritional disorder in this country and there has been a thirty percent increase in the incidence of obesity over the past ten years. The exact cause of this epidemic has not been determined, but more hectic lifestyles, with reduced time for exercise and increased caloric intake, have been identified as potential factors. The intake of fat has increased over the last eighty years, but the increased incidence of obesity was observed despite the availability of over 1,000 so-called fat-free foods. When sugar replaces fat in these foods, there is often no difference in caloric content as compared to the full-fat version, so that consumption of fat-free foods does not reduce calorie intake.

Obesity is a complex disorder for which no simple single solution will suffice.

Diagnosis and Vertically Integrated Management of Obesity







Nutrition 101 - Natural Remedies - Weight Management - Physician Education
Vitamins & Minerals - Nutrition & Aging - Nutrition & Disease - Research