OBESITY

OBESITY BY

DR.SEFEEN SAIF ATTYASOHAG TEACHING HOSPITAL

HISTORICAL ASPECTSHippocrates is reported to have said “sudden death is more common in those who are fat than in the lean”

The greeks were the first to recognize obesity as a medical disorder Hippocrates wrote that ‘corpulence is not only a disease itself,but the harbinger of others”During the Middle Ages obesity was often seen as a sign of wealth, and was relatively common among the elite

OBESITY Overweight and obesity are terms used to

describe individuals with an increased body fat, a certain amount of body fat is necessary for storing energy, heat insulation ,shock absorption,and other functions

Measuring fat accurately in human requires special equipments and so usually excess weight is defined by measuring the body mass index (BMI)

BMI is calculated by measuring a person’s weight in KG divided by that person’s height in meters squared (kg/m²) .for example an adult weighing 90 kg with a height of 1.8 m has a BMI of 27.8

• The internationally accepted classification of BMI in adults is as follows BMI Classification

< 18.5 underweight

18.5–24.9 normal weight

25.0–29.9 overweight

30.0–34.9 class I obesity

35.0–39.9 class II obesity

≥ 40.0   morbid obesity

AETIOLOGY OF OBESITY

1-FAMILIAL & GENETIC PREDISPOSITION• There is a number of known genetic

conditions which produce a syndrome complex associated with obesity

• The best known is the prader-willi syndrome which is associated with deletions on chromosome 15 resulting in excessive appetite

• The contribution to weight gain of transmission in susceptable families ranges from 25-40% ,this transmission is derived from both maternal & paternal lines

2- DRUGSCorticosteroids Tricyclic antidepressantsSulfonylureas for diabetes Steroidal contraceptives3-ENDOCRINE CAUSEScushing’s syndrome due to excess

corticosteroid productionHypothalamic tumoursHypothyroidism

4-AGEWeight increases with age at least up

to 60 years 5-GENDERWomen have a higher prevalence of

excess weight than men 6-FAT INTAKEprevalence is higher in those with high fat

intake

7-SMOKING CESSATION• Cessation of smoking increases

weight ,the average weight gain is 2.8 kg in males & 3.8 in females

8-PHYSICAL ACTIVITYDeclining physical activity predisposes

to weight gain such as sedentary jobs and certain pastimes e.g. watching television and computer games

Body fat percentage

• Body fat percentage can be estimated from a person's BMI by the following formula:

• Body fat % = 1.2(BMI)+0.23(age)-5.4-10.8(gender)

where gender is 0 if female and 1 if male This formula takes into account the fact that body fat percentage tends to be 10 % greater in women than in men for a given BMI. It recognizes that a person's percentage body fat tends to increase as they age, even if their weight and BMI remain constant.

Cross-sections of the torso of a person of normal weight (left) and an obese person (right), taken by CT scan. Note the 3.6 cm of subcutaneous fat on

the obese person.

Pathophysiology of Obesity

Genetics vs. Environment• The relative contributions of genetics and environment

to the etiology of obesity have been evaluated in many studies, 30% to 40% of the variance in BMI can be attributed to genetics and 60% to 70% to environment.

• The interaction between genetics and environment is also important. In a given population, some people are genetically predisposed to develop obesity, but that genotype may be expressed only under certain adverse environmental conditions, such as high-fat diets and sedentary lifestyles .In the United States, as well as in other Western countries, greater numbers of people are being exposed to these adverse environmental conditions, and consequently, the percentage of people expressing the obesity genotype has increased.

• the possible pathophysiological mechanisms involved in the development and maintenance of obesity.

• This field of research had been almost unapproached until LEPTIN was discovered in 1994. Since this discovery, many other hormonal mechanisms have been elucidated that participate in the regulation of appetite and food intake, storage patterns of adipose tissue, and development of insulin resistance.

• Leptin and ghrelin are considered to be complementary in their influence on appetite, with ghrelin produced by the stomach modulating short-term appetitive control (i.e. to eat when the stomach is empty and to stop when the stomach is stretched).

• Leptin is produced by adipose tissue to signal fat storage reserves in the body, and mediates long-term appetitive controls (i.e. to eat more when fat storages are low and less when fat storages are high).

• While leptin and ghrelin are produced peripherally, they control appetite through their actions on the central nervous system In particular, they and other appetite-related hormones act on the hypothalamus,.

• There are several circuits within the hypothalamus that contribute to its role in integrating appetite, the melanocortin pathway being the most well understood.[ The circuit begins with an area of the hypothalamus, the arcuate nucleus, that has outputs to the lateral hypothalamus (LH) and ventromedial hypothalamus(VMH), the brain's feeding and satiety centers, respectively.

• The arcuate nucleus contains two distinct groups of neurons. The first group neuropeptide Y (NPY) (AgRP) and has stimulatory inputs to the LH and inhibitory inputs to the VMH. The second group pro-opiomelanocortin(POMC) and cocaine- and amphetamine-regulated transcript(CART) and has stimulatory inputs to the VMH and inhibitory inputs to the LH. Consequently, NPY/AgRP neurons stimulate feeding and inhibit satiety, while POMC/CART neurons stimulate satiety and inhibit feeding.

• Both groups of arcuate nucleus neurons are regulated in part by leptin. Leptin inhibits the NPY/AgRP group while stimulating the POMC/CART group. Thus a deficiency in leptin signaling, either via leptin deficiency or leptin resistance, leads to overfeeding and may account for some genetic and acquired forms of obesity.[

A comparison of a mouse unable to produce leptin thus resulting in obesity (left) and a

normal mouse (right)

Metabolic Predictors of Weight GainThe development of obesity occurs when

the caloric intake is disproportionate to the energy expended. Three metabolic factors have been reported to be predictive of weight gain: - low adjusted sedentary energy expenditure, - high respiratory quotient (RQ; carbohydrate-to-fat oxidation ratio), and - low level of spontaneous physical activity

• The resting metabolic rate (RMR) is strongly correlated to fat-free mass (FFM) in both men and women . However, RMR is only one component of the total daily energy expenditure, which also includes the thermic effect of food and physical activity .

• RQ is the second potential metabolic predictor of weight gain. A low RQ of 0.7 suggests that a person is oxidizing more fat than carbohydrate, whereas a ratio of 1.0 suggests that more carbohydrate than fat is being oxidized

Patterns of Body-Fat Distribution

GYNOID DISTRIBUTION• Fat stored mainly around the hips

and thighs and this is characteristic of women

ANDROID DISTRIBUTION• Storage of fat primarily in the abdomen

producing abdominal obesity

TO CHECK FOR ABDOMINAL OBESITY

WAIST CIRCUMFERANCE• Waist circumference is measured

halfway between the superior iliac creast and the rib cage in the

High Risk• Men > 102 cm• Women > 88 cm

waist circumferences representing normal,

overweight, and obese

• WAIST-HIP RATIO (WHR)This ratio is derived from measuring the

waist circumference divided by the hip circumference ,both in centimeters

The hip circumference is measured one-third of the distance between the superior iliac spine and the patella

Abdominal obesity is a risk to health if the WHR is >0.95 in males or >0.8 in females

Health risks Associated with Obesity

Mortality• Obesity is one of the leading preventable

causes of death worldwide. Large-scale American and European studies have found that mortality risk is lowest at a BMI of 20–25 kg/m2 A BMI above 32 has been associated with a doubled mortality rate

• On average, obesity reduces life expectancy by six to seven years, a BMI of 30–35 reduces life expectancy by two to four years, while severe obesity (BMI > 40) reduces life expectancy by 10 years.

Type 2 Diabetes• The relative risk of developing type 2 diabetes

increases steeply with increasing BMI. This relationship is best demonstrated by the Nurses' Health Study, which prospectively followed up more than 114,000 registered nurses for 14 years . Women with BMI of 35 kg/m2 or greater had a 93 times higher risk of developing diabetes than those with BMI of <22 kg/m2.

• Even women who were overweight had higher risk; those with BMI of 25.0 to 26.9 kg/m2 and 27.0 to 28.9 kg/m2 had relative risks of 8.1 and 15.8, respectively.

• Abdominal obesity, as measured by waist-to-hip ratio, may be a stronger predictor of diabetes than BMI alone

CHD A relationship between obesity and CHD mortality

was demonstrated in the Nurses' Health Study . The relative risk of CHD death increased significantly with increasing BMI Women with BMI of 29.0 to 31.9 kg/m2 and 32.0 kg/m2 or higher were at 4.6 and 5.8 times greater risk, respectively, than those with BMI values under 22.0 kg/m2. Moreover, the waist-to-hip ratio was strongly predictive of CHD mortality.

Women in the highest quintile of waist-to-hip ratio had a relative risk of CHD death of 8.7 compared with those in the lowest quintile.

Hypertension• The risk of hypertension also increases with

increasing BMI. • The hypertension associated with obesity is

characterized by an increase in vascular volume, whereas peripheral resistance is generally borderline or only slightly elevated .

• Several mechanisms may be involved in the development of hypertension in obese subjects: increased renal sodium and water absorption, sympathetic nervous system activation, changes in Na+/H+-ATPase activity, and growth factor–mediated structural changes to the vascular wall. In each case, hyperinsulinemia may be a contributing factor.

CHRONIC ABDOMINAL COMPARTMENTATION SYNDROME

• Abdominal obesity espcially in the morbid obese individual can result in chronic abdominal compartmentation syndrome

• It is thought that the mass of omental fat increases intra-abdominal pressure resulting in stress incontinence as well as increased gastric acid reflux

• The tenting of the diaphragm can increase intra-thoracic pressure raising right atrial pressure with associated pulmonary hypertention and subsequent breathlessness

Dyslipidemia• Impaired glucose use and increased hepatic glucose

output are not the only consequences of the higher FFA levels in obesity. Increased FFAs also affect lipid metabolism by increasing very-low-density lipoprotein production by the liver, reducing high density lipoprotein (HDL)-cholesterol levels, and increasing the number of small, dense low-density lipoprotein (LDL) particles . These smaller particles are better able to penetrate the arterial wall, more readily undergo oxidation and glycation, and are more atherogenic than larger, LDL particles. Even when the LDL cholesterol level does not change appreciably, atherogenic risk may be higher because of the presence of the smaller LDL particles. Taken together, these changes in lipoprotein profile are associated with increased risk of CHD.

Bone and cartilage degeneration (Osteoarthritis) Obesity is an important risk factor for osteoarthritis in most joints, especially at the knee joint (the most important site for osteoarthritis). Obesity confers a nine times increased risk in knee joint osteoarthritis in women. Osteoarthritis risk is also linked to obesity for other joints.

Data suggest that metabolic and mechanical factors mediate the effects of obesity on joints (University of Bristol).

liver • Fatty infiltration of the liver • In morbidly obese with BMI greater

than 40 only 2% have normal livers , 56% shows fatty infiltration and 42% have fatty infiltration associated with fibrosis or cirrhosis

Gallbladder DiseaseIs the most common form of digestive

disease in obese individuals There is a progressive linear increased

risk of gallstones from a BMI of 20 upwards

Weight loss may actually exacerbate gall bladder disease this may be caused by the rise in the circulating cholesterol as adipose tissue stores are mobilized and increase in the rate of cholesterol excreated in bile

PREGNANCY• Increased risk of developing

gestational diabetes • Increased risk for pregnancy induced

hypertention• Increased risk for urinary tract

infectionOther complications include:Pre-eclampsia,thrombophlebitis,post-

partum haemorrhage,wound infection

Obese women have an increased risk of caeserean delivery owing to a variety of factors including:

Fetal sizeAn increase in maternal pelvic soft tissue

narrowing the birth canalProlonged labour Malpresentations Recently ,an inrcreased risk of neural tube

defects especially spina bifida ,has been reported in women with BMI greater than 29

RHEOLOGY• A number of haemostatic factors is

associated with weight gain , particularly factors which may relate to thrombosis and the risk of fatal myocardial infarction

• A 15% weight loss is associated with a decrease in blood viscosity by 20% and in haematocrite by 5.5% wheras plasma fibrinogen remains unaffected

Cancer

• The impact of obesity on cancer mortality was evaluated prospectively in a study of 750,000 men and women who were followed for 12 years . Men and women who were at least 40% overweight were 33% and 55% more likely, respectively, to die from cancer than those of average weight. Specifically, the mortality ratios for colorectal and prostate cancer in men and endometrial, uterine, cervical, ovarian, gallbladder, and breast cancer in women were highest among those who were at least 40% overweight.

• Similarly, in the Nurses' Health Study, cancer mortality increased with increasing BMI . The cancer death rate for women with BMI of 32 kg/m2 was twice that for women with BMI of less than 19 kg/m2.

Breast cancer Age has a significant impact on the risk of

developing breast cancer Pre-menopausal obese women have the same

risk as lean women ,but post menopausal women exhibit a higher risk

Abdominal obesity and a positive family history increase this risk

Central adiposity is associated with enhanced conversion of androgens to oestrogen in the fat mass and a reduced sex – hormone – binding globulin (SHBG) which adds to an increase in free oestradiol levels

MEDICAL MANAGEMENT OF OBESITY

The medical management of weight can be considered in four approaches based on the most recent advice given by the Royal college of physicians in scotland and england

1-Weight reduction2-weight maintenance plan3-drug therapy4-very –low-calorie diets

1-Weight reductionThis aims to provide a 3-month management plan

designed specifically to the needs of each individual patient

This comprises:A-a moderate reduction in energy intake of about 600

cal. ,this produces a greater weight loss than more strict diets due to improved compliance

B-behavioural modification therapy which is designed to support a process of change in the individual’s attitude regards food intake ,life style and physical activity

C-promotion of increased physical activity : walking briskly for 30 minutes each day can contribute to 200 cal. Of energy expenditure daily resulting in an additional weight loss of 1 kg. /month

Dietary changes• The Mayo Clinic advises obese people to

reduce their total daily calorie intake and to consume more fruits, vegetables and whole grains.

• It is important that your diet is varied - you still continue to enjoy the tastes of different foods.

The consumption of sugar, certain refined carbohydrates and some fats should be reduced significantly.Behavioural changes including advice nt to snack between meals ,not to buy excess food, and not to eat while feeling depressed

Physical activity

• The more you move your body the more calories you burn.

• To lose a kilogram of fat you need to burn 8,000 calories .

• Walking briskly is a good way to start increasing your physical activity if you are obese. Combining increased physical activity with a good diet will significantly increase your chances of losing weight successfully and permanently!

2-Weight maintenance planThe weight reduction is then followed by

a 3-month programme emphasizing weight maintenance

Exercise is designed to prevent weight regain once lost by dietary restriction for example moderate exercise of 30 min. of brisk walking each day can maintain a weight of 70 kg whereas without such extra activity the weight

Would plateau out on 77 kg on the same dietary intake

3-DRUG THERAPY

APPETITE SUPPRESSANTS(anorectic agents)

The first group :act on the hypothalamus influencing catecholaminergic pathway for example amphetamine

Because of their cerebral stimulant action and potential misuse all are restricted

The second group : act on the hypothalamic serotonergic system namely di-fenfluramine and dexfenfluramine

They have no cerebral stimulant or addictive activity

These two drugs were used worldwide for many years until their withdrawal in 1997 owing to their cardiopulmonary side effects

Prescription medications for losing weight

• Prescription medications should really only be considered as a last resort. if obesity has reached such a point as to significantly undermine health, then prescription drugs may become an option.

According to the Mayo Clinic prescription medications should only be considered if:

• Other strategies to lose weight have failed • The patient's BMI is over 27 and he also has diabetes,

hypertension, or sleep apnea. • The patient's BMI is over 30 • There are two approved drugs a physician may consider,

Sibutramine (Meridia in USA/Canada, Reductil in Europe and much of the world) or Orlistat (Xenical). Bear in mind that as soon as you stop taking these drugs the overweight problem generally comes back - they have to be taken indefinitely

FAT ABSORPTION INHIBITOR(orlistat)

Orlistat inhibits pancreatic and gastric lipases ,this produces a 30% reduction in dietary fat absorption which can contribute to a caloric deficit of about

Adverse side effects are mainly related to the effects of fat malabsorption on the gut

1-loose oily stools 2-flatus with discharge3-increased defecation 4-faecal incontinence Contraindications 1-chronic malabsorption states2-cholestases 3-hepatic failure4-Pregnancy5-breast feeding6-children

• Bulk forming drugs and diuretics should not be used to enhance fat loss

• Thyroid replacement therapy should only be used in obese persons when there is evidence of biochemical hyperthyroidism and not otherwise

4-VERY-LOW-CALORIE DIETS(VLCD)

• produce weight loss of 1.5-2.5 kg/week• They are used for short –term rapid weight loss • Considered only for obese persons with BMI >30Composition of the dietThe composition of the diet should ensure a

minimum of 50 gm of protein each day for men and 40 gm for women to minimize muscle degradation

• Energy content should be 400 cal for women and 500 cal for men

• Most use liquid feed although VLCD made of solid food are used but are less successful

Side effects Side effects may be a problem in the early stages of

the diet ,especially orthostatic hypotension ,headache ,diarrhoea and nausea

Contraindications1-cardiac disease ,unstable angina, recent myocardial

infarction ,significant cardiac arrythmias and cardiac failure

2-cerebrovascular disease ,recent stroke 3-unstable epilepsy4-major organ system failure 5- protein wasting conditions 6-pregnant women ,during breast feeding and in

children

Weight loss surgery (bariatric surgery)

There are two types of bariatric surgeries:• Restrictive procedures - These make the

stomach smaller. The surgeon may use a gastric band, staples, or both. After the operation the patient cannot consume more than about one cup of food during each sitting, significantly reducing food intake.

• Malabsorptive procedures - Parts of the digestive system, especially the first part of the small intestine (duodenum) or the mid-section (jejunum), are bypassed. Doctors may also reduce the size of the stomach. This procedure is generally more effective than restrictive procedures. However, the patient has a higher risk of experiencing vitamin/mineral deficiencies because overall absorption is reduced.

No patient should undergo bariatric(anti-obesity) surgery before

Medical investigation and treatment Psychological assessment has excluded

significant disorders and confirmed that the patient can cope with the severe dietary restriction imposed by the surgery

Weight reduction on medical therapy indicates compliance with the enforced dietary restrcition after surgery in addition it makes surgical intervention easier

INDICATIONSThe ideal patient is one who has :No major perioperative risk factors Stable personality and has no eating

disorders and who has come down to a BMI of 35 or less with medical management

CONTRAINDICATIONSMajor risk category for perioperative

cardiac complications Significant chronic obstructive lung

disease Non-compliance with medical therapyPsychological instabilityEating disordersHiatus herniaGastro-oesophageal reflux disease

INTRAGASTRIC BALLOON

• The principle of this intervention is to reduce gastric volume by inserting a silicon balloon that has a valve to which is attached a filling tube

• The deflated balloon is inserted into the stomach under I.V. sedation and local pharyngeal anaesthesia

• The position of the balloon is checked by flexible endoscopy

•

• The balloon is then filled with 800 mL saline and the filling tube is detached from the valve

• The position of the filled balloon is checked radiologically

• Intragastric balloons are not intended as a permanent solution but as a temporary over a period of 3-4 months to enable weight loss

VERTICAL BANDED GASTROPLASTY (VBG)

Vertical banded gastroplasty open or laparoscopic is the most commonly performed procedure

Its advantages include simplicity and ease of performance

Specific complications include • Bolus obstruction • Disruption of the staples partitioning

off the pouch (reduced by double stapling)

• Pouch dilatation

RESECTIONAL GASTRIC BYPASS(RGB)

this operation has been advocated recently and consists of subtotal gastrectomy with roux-en-Y reconstruction

It produces weight loss by a combination of reduced intake and malabsorption

Currently , this operation has to be regarded as a remedial procedure to be undertaken for failures after less major bar iatric operations

Patients who have undergone ( RGB)require long-term vit. B12 replacement and an oral iron therapy

Open Roux-en-Y Gastric Bypass(RYGB)

• RYGB is both a gastric restrictive procedure and a mildly malabsorptive procedure. A small gastric pouch restricts food intake, while the Roux-en-Y configuration provides malabsorption of calories and nutrients.

• Mason described the optimal parameters for restriction necessary for adequate weight loss, including a gastrojejunostomy of 1.2 cm or less in diameter and a gastric pouch of 15 to 30 mL.

Advantages• The RYGB is more effective than vertical banded gastroplasty in

terms of weight loss. The presence of dumping syndrome following gastric bypass may encourage patients to avoid sweets.

Disadvantages• Dumping syndrome occurs in a variable number of patients

following gastric bypass. It is due to rapid emptying of hyperosmolar boluses into the small bowel. Patients may experience bloating, nausea, diarrhea, and abdominal pain after ingesting sweets or milk products. Vasomotor symptoms such as palpitations, diaphoresis, Dumping syndrome may provide a beneficial effect in promoting weight loss by causing patients to avoid sweets.

• A few postoperative complications are specific to gastric bypass, including distal gastric distention and internal hernia. Distal gastric distention is often heralded by hiccups and left shoulder pain. Internal hernia may be difficult to diagnose. Patients may present with vague periumbilical pain, nausea, and vomiting. A radiographic upper gastrointestinal study is valuable in diagnosis. Operative repair is indicated, and involves reduction of the herniated bowel and suture closure of the mesenteric defect.

BILIOPANCREATIC DIVERSION

This intervention is popular on the Europian continent and results in substantial weight loss (average 70% at 2 years)

This operation consist of distal two-thirds gasterectomy with closure of the duodenal stump

The ileum is then transected 250 -350 cm from the ileo-caecal valve ,the distal end (alimentary limb=250-350 cm) is closed and brought up for end –to-side anastomosis with the gastric reminant

The proximal end (biliopancreatic limb) is anastomosed end –to-side to the alimentary limb about 50 cm from the ilio-caecal valve

Laparoscopic Adjustable Gastric Banding (LAGB)

• Adjustable gastric banding involves the minimally invasive (laparoscopic) or open-approach placement of a silicone band around the proximal stomach to restrict the amount of solid food that can be ingested at one time. Furthermore, the adjustable nature of the band allows the amount of restriction to be increased or decreased, depending upon the patient's weight loss. The Food and Drug Administration approved the laparoscopic adjustable gastric band for use in the United States in June 2001.

AdvantagesLaparoscopic adjustable gastric banding is a relatively

simple procedure that takes less operative time than the more complex procedures such as laparoscopic RYGB or laparoscopic biliopancreatic diversion. No staple lines or anastomoses are required. The adjustable nature of the laparoscopic band allows the degree of restriction to be optimized for the patient's weight loss.

Disadvantages• the need for frequent postoperative visits for band

adjustment. Some patients (5 to 10%) experience band slipping or gastric prolapse, which usually requires reoperation. Other potential problems include band erosion, gastroesophageal reflux, alterations in esophageal motility, and esophageal dilatation.

REMEMBER THAT• The under –excercising and over-eating are the

causes of obesity always walk as much as possible every day

• You can eat what you like and grow thin provided you make sure that your caloric intake is less than your caloric expenditure

• Mental work does not require additional calories• Alcohol may be an important factor in the

causation of obesity ,alcohol is used by the body solely as a source of energy and thus it frees an equivalent number of food calories which are then stored as fat

• To weigh yourself regularly this will show how successful are your efforts to reduce over weight

THANKYOU