obesity lec1

Absolute prevalence of obesity varies among countries (0.7-78.5). However, large rises in prevalence have been observed across the globe over the past few decades.

Overweight & obesity affect almost 2/3 (65.1%) of US adult.

The WHO estimates that over a billion adults are overweight & over 300 million are obese world wide. We are facing global obesity crises.

In USA, the prevalence of obesity in men, women & children is reported to be 28, 34 & 17% respectively.

It is a cause of major morbidity & mortality, is associated with numerous comorbidites such as cardiovascular diseases, type 2 diabetes, hypertension, sleep apnea/sleep disordered breathing, osteoarithritis as well as some cancers.

Obesity is associated with an increased risk of morbidity & mortality as well as reduced life expectancy, obesity responsible for more than 2.8 million deaths per year world wide.

@ Classification of obesity:

I- classification is based on number & size of adipose cell:

  1- Hypertrophic obesity: many individuals, often those with mild or moderate obesity beginning in middle age, have an adipose tissue with normal number of adipocytes but containing large quantities of fat in each cell.

  2- hyperplastic obesity: other individuals, often those with marked obesity & a history dating to early childhood, has an adipose depot made up of too many adipocytes each containing fat reasonably normal in quantity.

II- classification according to fat distribution:

  1- Android, apple shaped or upper body obesity: is associated with increased risk of diabetes, hypertension & cardiovascular diseases, this type of obesity is most common in males.

  2- Gynoid, pear shaped or lower body obesity: the fat distributed in the lower extremities around the hips or femoral region, is relatively benign & is common in females.

Note: a simple determination of waist to hip circumference can identify the two types of obesity (a ratio is about 0.7 is considered normal, > 0.7 upper body obesity, < 0.7 lower body obesity).

@ Causes of obesity:

   A- Primary: genetics, twin studies indicate strong correlation in body weight & body fatness between identical twins & it appears that heredity plays a substantial role in the development of obesity in this case.

Family studies show that obesity runs in families, but they do not critically separate environmental from genetic factors.

  B- secondary:

1- Excessive calories intake.

2- Inactivity.

3- Socioeconomic class: in the west, the low socio-economic class person is obese, while in the east, the high socio-economic class person is obese.

4- Endocrine disorder as myxoedema, Cushing syndrome.

@ Complications of obesity:

1- Diabetes: the prevalence of diabetes is about 2.9 times higher in overweight than in normal weight individuals (poor control of NIDDM)

2- Cerebrovascular: obesity is major risk factor to CVA.

3- Coronary heart disease: increase TG &/or cholesterol, high Bpr.

4- Respiratory complications as dyspnea.

5- Gout & arthritis.

6- Gall stones.

7- Cancer: ca. colon & prostate in males & of the breast in females.

8- Undesirable social, psychological & economic consequences of obesity.