Obesity and overweight

Obesity and overweight

1. Liver Anatomy

   • The upper surface of the liver is percussed at the level of the fifth intercostal space. Superior, anterior, posterior and right surfaces of the liver are continuous with each other and are related to the diaphragm and anterior abdominal wall.
   • The anterior surface is separated from the inferior (visceral) surface by a sharp anterior (inferior) border that is clinically palpable on deep inspiration. The inferior surface is related to the hepatic flexure (the area where the vertical ascending (right) colon takes a right-angle turn to become the horizontal transverse colon), right kidney, transverse colon, duodenum and stomach. The gallbladder straddles the undersurfaces of liver segments IVB and V.
   • Blood Supply The liver has a unique dual blood supply (about 1500 mL/min) both from the proper hepatic artery (20-40%) and from the portal vein (60-80%

2. Microscopic Anatomy

   • The surface of the liver is covered by visceral peritoneum (serosa), with a Glisson capsule underneath. At the porta hepatis, the Glisson capsule travels along the portal tracts (triads), carrying branches of the hepatic artery, the portal vein, and the bile ducts into the liver substance.
   • Sinusoids are large-diameter capillaries lined by endothelial cells between rows of plates or cords of hepatocytes. Sinusoids also contain Kupffer cells of the reticuloendothelial system (RES). Each hexagonal lobule has a central portal tract with branches of the hepatic artery, the portal vein, and bile ducts, as well as a peripheral tributary of the hepatic vein. Bile canaliculi between hepatocytes drain into bile ductules in the portal triad. Bile ductules then form several orders of intrahepatic bile ducts, in an arrangement resembling the twigs and branches of a tree.

3. BMI

   • Grade 1 overweight (commonly and simply called overweight) - BMI of 25-29.9 kg/m 2
     • Grade 2 overweight (commonly called obesity) - BMI of 30-39.9 kg/m 2
       • Grade 3 overweight (commonly called severe or morbid obesity) - BMI ≥40 kg/m 2
   • Some authorities advocate a definition of obesity based on percentage of body fat, as follows:
     • Men: Percentage of body fat greater than 25%, with 21-25% being borderline
     • Women: Percentage of body fat great than 33%, with 31-33% being borderline

4. comorbidities related to obesity

   • Respiratory: Obstructive sleep apnea, [4] greater predisposition to respiratory infections, increased incidence of bronchial asthma, and Pickwickian syndrome (obesity hypoventilation syndrome)
     • Malignant: Reported association with endometrial (premenopausal), prostate, colon (in men), rectal (in men), breast (postmenopausal), gall bladder, gastric cardial, biliary tract system, pancreatic, ovarian, renal, and possibly lung cancer, as well as with esophageal adenocarcinoma and multiple myeloma
       • Psychological: Social stigmatization and depression
         • Cardiovascular: Coronary artery disease, [8] essential hypertension, left ventricular hypertrophy, cor pulmonale, obesity-associated cardiomyopathy, accelerated atherosclerosis, and pulmonary hypertension of obesity
           • Gastrointestinal (GI): Gall bladder disease (cholecystitis, cholelithiasis), nonalcoholic steatohepatitis (NASH), fatty liver infiltration, and reflux esophagitis
             • Cutaneous: Intertrigo (bacterial and/or fungal), acanthosis nigricans, hirsutism, and increased risk for cellulitis and carbuncles
               • Extremity: Venous varicosities, lower extremity venous and/or lymphatic edema
                 • Miscellaneous: Reduced mobility and difficulty maintaining personal hygiene

5. Diagnosis

   • Laboratory studies
     • Fasting lipid panel Liver function studies Thyroid function tests Fasting glucose and hemoglobin A1c (HbA1c)
   • Evaluation of degree of body fat
     • Caliper-derived measurements of skin-fold thickness Dual-energy radiographic absorptiometry (DEXA) Bioelectrical impedance analysis Ultrasonography to determine fat thickness Underwater weighing

6. possible causes

7. diets

   • Atkins diet
     • If people consume large amounts of refined carbohydrates, their insulin levels rise and fall rapidly. Rising insulin levels trigger the body to store energy from the food that is consumed, making it less likely that the body will use stored fat as a source of energy.
   • Zone diet
     • The Zone diet encourages the consumption of high-quality carbohydrates - unrefined carbohydrates, and fats, such as olive oil, avocado, and nuts.
   • Vegetarian diet
     • The majority of vegetarians are lacto-ovo vegetarians, in other words, they do not eat animal-based foods, except for eggs, dairy, and honey.

8. Physiology of hunger

   • Craving for food (need to eat) Associated with other physiological factors e.g. release of Ghrelin, rhythmical contractions of stomach. Seeking an adequate food supply. No direct mechanisms to inhibit hunger.
   • Neuronal control of food intake
     • Feeding center:
       • Lateral nuclei of the hypothalamus
     • Satiety center:
       • Ventro-medial nuclei of the hypothalamus (VNH)

9. surgery

   • gastric banding
     • In gastric banding surgery, no part of the stomach is removed .Either staples or a band are used to separate the stomach into two parts, one of which is a very small pouch that can hold about one ounce of food. The food from this "new" stomach empties into the closed-off portion of the stomach and then resumes the normal digestive process.
   • gastric bypass
     • surgeon makes a small stomach pouch by stapling part of the stomach together or by vertical banding. This limits how much food you can eat. Next, the surgeon attaches a Y-shaped section of the small intestine to the pouch. That creates a bypass for food
   • sleeve gastrectomy
     • the stomach is reduced to about 15% of its original size, by surgical removal of a large portion of the stomach along the greater curvature. The result is a sleeve or tube like structure. The procedure permanently reduces the size of the stomach, although there could be some dilatation of the stomach later on in life.

10. Drugs

    • With the exception of orlistat, medications indicated for obesity target appetite mechanisms. The medications available for obesity treatment work primarily in the arcuate nucleus to stimulate the POMC neurons, which promote satiety.
      • Phentermine  Topiramate/phentermine  Lorcaserin  Natrexone/bupropion  Liraglutide