Obesity and metabolic syndrome
Obesity
Simple definition, see the table.
The prevalence of comorbidities and risk of future morbidities increase considerably at a BMI >30. A waist circumference of >102cm for men and >88cm for women are indicators of increased metabolic risk as well.
Etiology is genetic and environmental, twin studies have shown that a significant portion of weight variation is genetic, although of course a large part of it is based on lifestyle factors.
Excess energy consumed by adults is generally stored as triglycerides in adipocytes. Increases can be as a result of hyperplasia (increased fat cell numbers) or hypertrophy (increased fat cell size). Those who gain fat with hypertrophy (commonly abdominal fat) generally have a greater inflammatory response, are more likely to be insulin resistant and suffer from other systemic diseases. Leptin is a cytokine protein that is secreted by adipocytes and is shown to have an effect on the CNS, and it effects food intake (leptin deficient animals eat a lot more (hyperphagic) and become obese). Other peripheral signals also change the amount we want to eat, review the table below that shows the effect different biological modulators have on food intake.
As well as having too much of an +ve energy balance, around 1% of the obese popuation have a diseaes that can explain their obesity. These diseases include Cushings, hypothalamic damage, insulinoma and hypothyroidism.
Diseases associated with obesity include:
- Hypertension
- Coronary artery disease
- Cancer
- Diabetes mellitus
- Gallstones
Metabolic syndrome
This is a combination of at least three of the following conditions:
- Abdominal obesity
- Hypertension
- Hyperglycemia
- Hypertriglyceridemia
- Low HDL levels
The syndrome is associated with increased risk of cardiovascular disease and type II diabetes. In the US about ¼ of the adult population of metabolic syndrome