الفهرس 
Definition, etiology, pathophysiology andOnly 14 pages are availabe for public view
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Abstract
Obesity has increased prevalence to the extent that it has
reached epidemic proportions and became a major public health
concern.
Morbid obesity is considered a disease of excess energy
stores in the form of fat. Clinically severe obesity correlates with
a Body Mass Index (BMI) of greater than or equal to 40 kg/m2 or
a BMI of greater than or equal to 35 kg/m2 accompanied by
comorbid conditions.
The cause of obesity is complex and multifactorial and
includes genetic factors, microbiological factor, environmental
factors, behavioral factors, psychological factors, eating disorders,
endocrine causes and drug induced obesity. There are several
factors that are sharing in pathogenesis of obesity including
hormonal and enzymatic cause.
Obesity increases the risk of many physical and mental
conditions, obesity complications are either directly caused by
obesity or indirectly related as diabetes mellitus, hypertension,
dyslipidaemia, cardiovascular disease, atherosclerosis,
cerebrovascular disease, pulmonary dysfunction, gastroesophageal
reflux, cholelithiasis, non-alcoholic fatty liver disease,
deep venous thrombosis, pulmonary embolism, degenerative joint
disease, genital disorders, gestational diabetes, pre-eclampsia, and
delivery complications.
Effective weight loss therapy can reverse many of the
adverse effects of severe obesity. Available therapies include lifestyle changes (diet and exercise), very-low-calorie diets,
pharmacologic therapy, and surgery. Of these, bariatric surgery is
documented as the most consistently effective therapeutic
intervention for the severely obese.
Surgery is usually successful in inducing substantial weight
loss in the majority of obese patients with improvement or
reversal of obesity-related comorbidities and is achieved
primarily by an inevitable reduction in energy intake.
Bariatric procedures are based on two primary principles to
promote weight loss: gastric restriction and intestinal malabsorption.
Roux-en-Y gastric bypass (RYGB) is considered the
most common restrictive and mal-absorption procedure that
surgically alters the stomach capacity using surgical staples.
Weight loss is promoted by the restriction of the amount of food
and limitation of the absorption of food.
Complications of bariatric surgery could be classified into
surgical and nutritional complications; furthermore, the surgical
complications could be subdivided into early (<2 months) and late
complications and includes: Anastomotic or staple line leaks,
postoperative hemorrhage, venous thromboembolism, acute
gastric distension, small bowel obstruction, gastro-jejunostomy
anastomotic stricture, Marginal ulceration, Internal hernia, gastrogastric
fistula, gall stone disease and weight gain plus nutritional
complications which includes: vitamin B12 deficiency, Iron
deficiency, calcium and vitamin D deficiency, vitamin B9
(folates) deficiency, protein and carbohydrates deficiency. Nutrient deficiencies after bariatric surgery are common
and have multiple causes. Preoperative factors include obesity,
which appears to be associated with risk for several nutrient
deficiencies, and preoperative weight loss. Postoperatively,
reduced food intake, suboptimal dietary quality, altered digestion
and absorption, and nonadherence with supplementation regimens
contribute to risk of deficiency.
The most common clinically relevant micronutrient
deficiencies after gastric bypass include thiamine, vitamin B12,
vitamin D, iron, and copper. Reports of deficiencies of many
other nutrients, some with severe clinical manifestations, are
relatively sporadic. Diet and multivitamin use are unlikely to
consistently prevent deficiency, thus supplementation with
additional specific nutrients is often needed. Though optimal
supplement regimens are not yet defined, most micronutrient
deficiencies after gastric bypass currently can be prevented or
treated by appropriate supplementation.