presented by: mr. sultan alenazi 1.  overweight.  causes of obesity.  treatment of obesity....

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  • Slide 1
  • Presented By: Mr. Sultan Alenazi 1
  • Slide 2
  • Overweight. Causes of obesity. Treatment of obesity. Weight management. Weight maintenance. Underweight. 2
  • Slide 3
  • Obesity: is an excessive accumulation of energy in the form of body fat which impairs health. 3 ClassificationBMI UnderweightBelow 18.5 Normal 18.5 - 24.9 Overweight > 25.0 Pre-obese 25 - 29.9 Obese class I 30.0 - 34.9 Obese class II 35.0 - 39.9 Obese class III > 40.0
  • Slide 4
  • Recently, study made in Saudi Arabia showed the obesity and overweight are increasing in KSA with an overall obesity prevalence of 35.5%. Overweight defined by BMI of 25 or greater. Obesity is so widespread and its prevalence is rising so rapidly that many refer to it as an epidemic. Before examining the suspected causes of obesity and myriad treatments used to overcome it, it may be helpful to understand the development and metabolism of body fat. 4 Study made by Dr.Al-Nozha and others between 1995-2000.
  • Slide 5
  • Fat cell development When more energy consumed than is spent, much of the excess energy is stored in the fat cells of adipose tissue. The amount of fat in a persons body reflects both the number and size of the fat cells. The number of fat cells increases most rapidly during the growing years of late childhood and early puberty. Fat cell number increases more rapidly in obese children than in lean children, and obese children entering their teen years may already have as many fat cells as do adults of normal weight. 5
  • Slide 6
  • The fat cells expand in size as they fill with fat droplets, when the cells reach their maximum size, they may also divide. Thus obesity develops when a persons fat cells increase in number, size or both. With fat loss, the size of fat cells shrinks, but not their number, so people with extra fat cells tend to regain lost weight rapidly. 6
  • Slide 7
  • 7 During growth, fat cells increase in number. When energy intake exceeds expenditure, fat cells increase in size. When fat cells have reached their maximum size and energy intake continues to exceed energy expenditure, fat cells increase in number again. With fat loss, the size of the fat cells shrinks, but not the number. Fat Cell Development
  • Slide 8
  • Fat cell metabolism The enzyme lipoprotein lipase (LPL) promotes fat storage in both adipose and muscle cells. People with high LPL activity store fat especially efficiently. Because LPL is mounted on fat cell membranes and obese people have many fat cells, they generally have much more LPL activity in their fat cells than lean people do. Consequently, even modest excesses in energy intake have a more dramatic impact on obese people than on lean people. 8
  • Slide 9
  • The activity of LPL is partially regulated by gender-specific hormones- estrogen in women and testosterone in men. In women, fat cells in the breasts, hips and thighs produce abundant LPL, putting fat away in those body sites; in men, fat cells in the abdomen produce abundant LPL. This enzyme activity explains why men tend to develop central obesity whereas women more readily develop lower-body fat. Differences are also apparent in the activity of the enzymes controlling fat breakdown in various parts of the body. The lower body is less active than the upper body in releasing fat from storage. Consequently, people tend to have a more difficult time losing fat from the hips and thighs than from around the chest and abdomen. 9
  • Slide 10
  • Set Point Theory Many internal physiological variables, such as blood glucose, blood PH and body temperature, remain fairly stable under a variety of conditions. The hypothalamus and other regulatory centers constantly monitor and delicately adjust conditions so as to maintain homeostasis. The stability of such complex systems may depend on set point regulators that maintain variables within specified limits. Researchers have confirmed that after weight gain or losses, the body adjust its metabolism so as to restore the original weight. Energy expenditure increases after weight gain and decreases after weight loss. These changes in energy expenditure differ from those expected based on body composition and help to explain why it is so difficult for an underweight person to maintain weight gains and an overweight person to maintain weight losses. 10
  • Slide 11
  • 1)Genetics. 2)Environment. Genetics Genetics have important role in determining a persons susceptibility to obesity. Genes may not cause obesity, but genetic factors may influence the food intake and activity patterns that lead to it and the metabolic pathways that maintain it. Genetic makes a person more or less likely to gain or lose weight when overeating or undereating. Some people gain more weight than others on comparable energy intake. Similarly, some people lose more weight than others following comparable exercise routines. 11
  • Slide 12
  • Leptin Leptin: a protein produced by fat cells under direction of ob gene that decreases appetite and increases energy expenditure; sometimes called the ob protein. Leptin acts as a hormone, primarily in the hypothalamus. It promotes a negative energy balance by suppressing appetite and increasing energy expenditure. Leptin blood levels correlate directly with body fat: the more body fat, the more leptin. Obese people generally have high leptin levels and when people with low leptin levels gain weight, their leptin concentrations increase. But its action is ineffective in obesity ( obesity is associated with an insensitivity and resistance to leptin). Perhaps leptin or its receptors are defective or other signals override its action. 12
  • Slide 13
  • 13 Positive energy balanceNegative energy balance 1)Loss of body fat.1) Gain of body fat. 2) Blood leptin decreases. 2) Blood leptin increases. 3)Hypothalamus responds, stimulating appetite. 3) Hypothalamus responds, diminishing appetite. 4)Food intake increases and energy expenditure decreases. 4) Food intake decreases and energy expenditure increases. Leptins action in the body
  • Slide 14
  • 14 leptin Central effects Food intake Reversal of hypothalamic thyroid and gonadal dysfunction Peripheral effects T-cell number and function Indirect effects Improved metabolic profile Insulin Cholesterol Triglycerides HDL-cholesterol
  • Slide 15
  • Uncoupling proteins Other genes code involved in energy metabolism. These proteins may influence obesity by storing or spending energy with different efficiencies or in different types of fat. The body has two types of fat: white and brown adipose tissue. White adipose tissue stores fat for other cells to use for energy; brown adipose tissue releases stored energy as heat. When fat is oxidized, some of the energy is released in heat and some is captured in ATP. In brown adipose tissue, oxidation may be uncoupled from ATP formation; it produces heat only. Radiating energy away as heat enables the body to spend, rather than store, energy. 15
  • Slide 16
  • Researchers working on the protein that uncouples reactions in brown adipose tissue discovered a gene that codes for a second uncoupling protein. This protein is active not only in brown fat, but in white fat and many other tissues as well. Its actions seems to influence the basal metabolic rate (BMR) and oppose the development of obesity. Animals with abundant amount of this protein resist weight gain, whereas those with minimal amounts gain weight easily. Similarly, children with a genetic variant of this uncoupling protein are more overweight than others. 16
  • Slide 17
  • Environment The environment includes all of the circumstances that we encounter daily that push us toward fatness or thinness, such as: Overeating. Physical inactivity. 17
  • Slide 18
  • Drugs Sibutramine (Meridia): a drug used in the treatment of obesity that slows the reabsorption of serotonin in the brain, thus suppressing appetite and creating a feeling of fullness. ( most effective when used in combination with a reduced-kcalorie diet and increased physical activity). Orlistat (Xenical): a drug used in the treatment of obesity that inhibits the absorption of fat in the GI tract, thus limiting kcaloric intake. ( It inhibits pancreatic lipase activity, thus blocking dietary fat digestion and absorption by about 30%. The drug is taken with medication and is most effective when used in combination with a reduced-kcalorie, low fat diet). 18
  • Slide 19
  • 19 DrugsActionsSide Effects Sibutramine (Meridia) Suppresses appetite by inhibiting the uptake of serotonin*. Dry mouth, headache, constipation, insomnia and high blood pressure. Orlistat (Xenical) Inhibiting pancreatic lipase activity.Gas formation, frequent bowel movements and reduced absorption of fat-soluble vitamins. * Serotonin: is a neurotransmitter important in sleep regulation, appetite control and sensory perception among other roles. It is synthesized in the body from the amino acid tryptophan with the help of vitamin B6.
  • Slide 20
  • Surgery Surgery as an approach to weight loss is justified in some specific cases of clinically severe obesity morbid obesity ( BMI of 40 or greater). Surgical procedures effectively limit food intake by reducing the size of the stomach. They reduce the size of the outlet as well, so they delay the passage of food from the stomach into the intestine for digestion and absorption. The safe

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