What is obesity and its causes?What are the main types of gastric surgery used for weight loss?

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अतिरिक्त मोटापे का कारण

WHAT IS A OBESITY

In a world where food supplies are intermittent, the ability to store
energy in excess of what is required for immediate use is essential for
survival.

Fat cells, residing within widely distributed adipose tissue
depots, are adapted to store excess energy efficiently as triglyceride
and, when needed, to release stored energy as free fatty acids for use at
other sites. This physiologic system, orchestrated through endocrine and
neural pathways, permits humans to survive starvation for as long as
several months.

DEFINITION AND MEASUREMENT
Obesity is a state of excess adipose tissue mass. Although often viewed
as equivalent to increased body weight, this need not be the case—lean
but very muscular individuals may be overweight by numerical stan-
dards without having increased adiposity.

Body weights are distributed
continuously in populations, so that choice of a medically meaningful
distinction between lean and obese is somewhat arbitrary. Obesity is
therefore defined by assessing its linkage to morbidity or mortality.
Although not a direct measure of adiposity, the most widely used
method to gauge obesity is the body mass index (BMI), which is equal
to weight/height2
(in kg/m2)

  • Obesity describe a weight of 120% or above.obesity is often expressed in terms of body mass index BMI is calculated by measuring an individual weight in kg .and dividing his , height, in meters square
  • Causes of obesity:
  • inherited causes
  • Classification. BMI. associated health risk

Pear types , apple type

Effect of obesity

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Neurological Disease

liver Disease

irregular menses

pregnancy,

Stage 1) BMI perfusion, impaired exercise,

stage 2)BMI 27-35kg Dyspnoea reduced lungs and chest wall

stage 3)BMI >35KG Pulmonary hypertension and right heart

failure, hypercapnia, obesity, hypoventilation syndrome,

Evaluation and Management
of Obesity

More than 66% of U.S. adults are categorized as overweight or obese,
and the prevalence of obesity is increasing rapidly in most of the
industrialized world.

Children and adolescents also are becoming more
obese, indicating that the current trends will accelerate over time. Obe-
sity is associated with an increased risk of multiple health problems,
including hypertension, type 2 diabetes, dyslipidemia, obstructive
sleep apnea, nonalcoholic fatty liver disease, degenerative joint disease,
and some malignancies.

Thus, it is important for physicians to iden-
tify, evaluate, and treat patients for obesity

TREATMENT
Obesity
THE GOAL OF THERAPY

The primary goals of treatment are to improve obesity-related
comorbid conditions and reduce the risk of developing future comor-
bidities. Information obtained from the history, physical examina-
tion, and diagnostic tests is used to determine risk and develop a
treatment plan. The decision of how aggressively to


treat the patient and which modalities to use is determined by the
patient’s risk status, expectations, and available resources. Not all
patients who are deemed obese by BMI alone need to be treated, as
exemplified by the concepts of obesity paradox or the metabolically
healthy obese. However, patients who present with obesity-related
comorbidities and who would benefit from weight-loss intervention
should be managed proactively.

Therapy for obesity always begins
with lifestyle management and may include pharmacotherapy or
surgery, depending on BMI risk category.

LIFESTYLE MANAGEMENT
Obesity care involves attention to three essential elements of life-
style: dietary habits, physical activity, and behavior modification.
Because obesity is fundamentally a disease of energy imbalance,
all patients must learn how and when energy is consumed (diet),
how and when energy is expended (physical activity), and how to
incorporate this information into their daily lives (behavioral ther-
apy). Lifestyle management has been shown to result in a modest
(typically 3–5 kg) weight loss when compared with no treatment or
usual care.

Diet Therapy The primary focus of diet therapy is to reduce
overall calorie consumption. Guidelines from the American Heart
Association/American College of Cardiology/The Obesity Society
(AHA/ACC/TOS) recommend initiating treatment with a calorie
deficit of 500–750 kcal/d compared with the patient’s habitual
diet.

Alternatively, a diet of 1200–1500 kcal/d for women and
1500–1800 kcal/d for men (adjusted for the individual’s body
weight) can be prescribed. This reduction is consistent with a goal
of losing ~1–2 lb/week.

The calorie deficit can be instituted through
dietary substitutions or alternatives. Examples include choosing
smaller portion sizes, eating more fruits and vegetables, consum-
ing more whole-grain cereals, selecting leaner cuts of meat and
skimmed dairy products, reducing consumption of fried foods and
other foods with added fats and oils, and drinking water instead of
sugar-sweetened beverages. It is important that dietary counseling
remains patient centered and that the selected goals are SMART
(specific, measurable, agreed upon, realistic, timely).


The macronutrient composition of the diet will vary with the
patient’s preference and medical condition. The 2015 U.S. Department
of Agriculture Dietary Guidelines for Americans , which
focus on health promotion and risk reduction, can be applied to treat-
ment of patients who are overweight or obese. The recommendations
include maintaining a diet rich in whole grains, fruits, vegetables, and


dietary fiber; decreasing sodium intake to <2300 mg/d; consuming fat-free or low-fat dairy products; and keeping added sugars and saturated fat intake to <10% of daily calories. Application of these guidelines to specific calorie goals can be found on the website Since portion control is one of the most difficult strategies for patients to manage, the use of preprepared products such as meal replacements is a simple and convenient suggestion. Examples include frozen entrees, canned beverages, and bars. Use of meal replacements in the diet has been shown to result in a 7–8% weight loss.

Numerous randomized trials comparing diets of different macro- nutrient composition (e.g., low-carbohydrate, low-fat, Mediterra- nean) have shown that weight loss depends primarily on reduction of total caloric intake and adherence to the prescribed diet, not the specific proportions of carbohydrate, fat, and protein in the diet.

The macronutrient composition will ultimately be determined by the patient’s taste preferences, cooking style, and culture. How- ever, the patient’s underlying medical problems are also important in guiding the recommended dietary composition.

The dietary pre- scription will vary according to the patient’s metabolic profile and risk factors. A consultation with a registered dietitian for medical nutrition therapy is particularly useful in considering patient pref- erence and treatment of comorbid diseases. Another dietary approach to consider is based on the concept of energy density, which refers to the number of calories (i.e., amount of energy) a food contains per unit of weight. People tend to ingest a constant volume of food regardless of caloric or macronutrient content. Adding water or fiber to a food decreases its energy density by increasing weight without affecting caloric content.

Examples of foods with low-energy density include soups, fruits, vegetables, oat- meal, and lean meats. Dry foods and high-fat foods such as pretzels, cheese, egg yolks, potato chips, and red meat have a high-energy density. Diets containing low-energy-dense foods have been shown to control hunger and thus to result in decreased caloric intake and weight loss. Occasionally, very low-calorie diets (VLCDs) are prescribed as a form of aggressive dietary therapy.

The primary purpose of a VLCD is to promote a rapid and significant (13- to 23-kg) short-term weight loss over a 3- to 6-month period. The proprietary formulas designed for this purpose typically supply ≤800 kcal, 50–80 g of protein, and 100% of the recommended daily intake for vitamins and minerals. According to a review by the National Task Force on the Prevention and Treatment of Obesity, indications for initiating a VLCD include the involvement of well-motivated individuals who are moderately to severely obese (BMI, >30 kg/m2 have


failed at more conservative approaches to weight loss, and have
a medical condition that would be immediately improved with
rapid weight loss. These conditions include poorly controlled type 2
diabetes, hypertriglyceridemia, obstructive sleep apnea, and symp-
tomatic peripheral edema. The risk for gallstone formation increases

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exponentially at rates of weight loss >1.5 kg/week (3.3 lb/week). 2847
Prophylaxis against gallstone formation with ursodeoxycholic acid
(600 mg/d) is effective in reducing this risk.

VLCDs should be used
only in limited circumstances and only when provided by trained
practitioners in a medical care setting where medical monitoring
and high intensity lifestyle intervention can be provided. Medical
supervision is required because of the rapid rate of weight loss and
potential for health complications.


Physical Activity Therapy Although exercise alone is only moder-
ately effective for weight loss, the combination of dietary modifica-
tion and exercise is the most effective behavioral approach for the
treatment of obesity. The most important role of exercise appears to
be in the maintenance of the weight loss. The Physical Activity
Guidelines for Americans recommend


that adults should engage in 150 min of moderate-intensity or
75 min a week of vigorous-intensity aerobic physical activity per
week, performed in episodes of at least 10 min and preferably
spread throughout the week.

Focusing on simple ways to add
physical activity into the normal daily routine through leisure
activities, travel, and domestic work should be suggested. Exam-
ples include brisk walking, using the stairs, doing housework and
yard work, and engaging in sports. Asking the patient to wear a
pedometer or accelerometer to monitor total accumulation of steps
or kcal expended as part of the activities of daily living is a use-
ful strategy.

Step counts are highly correlated with activity level.
Studies have demonstrated that lifestyle activities are as effective
as structured exercise programs for improving cardiorespiratory
fitness and weight loss. A high level of physical activity (>300 min
of moderate-intensity activity per week) is often needed to lose
weight and sustain weight loss. These exercise recommendations
are daunting to most patients and need to be implemented gradu-
ally. Consultation with an exercise physiologist or personal trainer
may be helpful.


Behavioral Therapy Cognitive behavioral therapy is used to help
change and reinforce new dietary and physical activity behaviors.
Strategies include self-monitoring techniques (e.g., journaling,
weighing, and measuring food and activity); stress management;
stimulus control (e.g., using smaller plates, not eating in front of
the television or in the car); social support; problem solving; and
cognitive restructuring to help patients develop more positive and
realistic thoughts about themselves.

When recommending any
behavioral lifestyle change, the patient should be asked to identify
what, when, where, and how the behavioral change will be per-
formed. The patient should keep a record of the anticipated behav-
ioral change so that progress can be reviewed at the next office visit.
Because these techniques are time consuming to implement, their
supervision is often undertaken by ancillary office staff, such as a
nurse-clinician or registered dietitian.


PHARMACOTHERAPY

Adjuvant pharmacologic treatments should be considered for patients
with a BMI ≥30 kg/m2
or for patients with a BMI ≥27 kg/m2
who
have concomitant obesity-related diseases and for whom dietary
and physical activity therapy has not been successful. When an
antiobesity medication is prescribed, patients should be actively
engaged in a lifestyle program that provides the strategies and skills
needed to use the drug effectively, since such support increases total
weight loss.


Medications for obesity have traditionally fallen into two major
categories: appetite suppressants (anorexiants) and gastrointestinal
fat blockers.. Four new antiobesity medications have been approved
by the U.S. Food and Drug Administration (FDA) since : lor-
caserin, phentermine/topiramate (PHEN/TPM) extended release,
naltrexone sustained release (SR)/bupropion SR, and liraglutide.
Gastrointestinal fat blockers reduce the absorption of selective
macronutrients, such as fat, from the gastrointestinal tract.


Centrally Acting Anorexiant Medications Anorexiants affect sati-
ety (the absence of hunger after eating) and hunger (the biologic
sensation that prompts eating). By increasing satiety and decreasing
hunger, these agents help patients reduce caloric intake without a
sense of deprivation. The target site for the actions of anorexiants
is the ventromedial and lateral hypothalamic regions in the central
nervous system The biologic effect of these agents.


on appetite regulation is produced by augmentation of the neu-
rotransmission of three monoamines: norepinephrine; serotonin
(5-hydroxytryptamine [5-HT]); and, to a lesser degree, dopamine.
The classic sympathomimetic adrenergic agents (benzphetamine,
phendimetrazine, diethylpropion, mazindol, and phentermine)
function by stimulating norepinephrine release or by blocking its
reuptake. Among the anorexiants, phentermine is the most com-
monly prescribed; there are limited long-term data on its effective-
ness. A 2002 review of six randomized, placebo-controlled trials
of phentermine for weight control found that patients lost 0.6–6.0
additional kg of weight over 2–24 weeks of treatment. The most
common side effects of the amphetamine-derived anorexiants are
restlessness, insomnia, dry mouth, constipation, and increased
blood pressure and heart rate.


PHEN/TPM is a combination drug that contains a catecholamine
releaser (phentermine) and an anticonvulsant (topiramate). Topira-
mate is approved by the FDA as an anticonvulsant for the treatment
of epilepsy and for the prophylaxis of migraine headaches. Weight
loss was identified as an unintended side effect of topiramate
during clinical trials for epilepsy. The mechanism responsible for
weight loss is uncertain but is thought to be mediated through the
drug’s modulation of γ-aminobutyric acid receptors, inhibition of
carbonic anhydrase, and antagonism of glutamate.

PHEN/TPM
has undergone two 1-year pivotal randomized, placebo-controlled,
double-blind trials of efficacy and safety: EQUIP and CONQUER.
In a third study, SEQUEL, 78% of CONQUER participants con-
tinued to receive their blinded treatment for an additional year.
All participants received diet and exercise counseling. Partici-
pant numbers, eligibility, characteristics, and weight-loss outcomes
are displayed in Table 395-5. Intention-to-treat 1-year placebo-
subtracted weight loss for PHEN/TPM was 9.3% (15-mg/92-mg
dose) and 6.6% (7.5-mg/46-mg dose), respectively, in the EQUIP
and CONQUER trials.

Clinical and statistical dose-dependent
improvements were seen in selected cardiovascular and metabolic
outcome measurements that were related to the weight loss. The
most common adverse events experienced by the drug-randomized
group were paresthesias, dry mouth, constipation, dysgeusia, and
insomnia. Because of an increased risk of congenital fetal oral-cleft
formation from topiramate, women of childbearing age should
have a negative pregnancy test before treatment and monthly
thereafter, and use effective contraception consistently during med-
ication therapy.


Lorcaserin is a selective 5-HT2C receptor agonist with a func-
tional selectivity ~15 times that of 5-HT2A receptors and 100 times
that of 5-HT2B receptors. This selectivity is important, since the
drug-induced valvulopathy documented with two other seroton-
ergic agents that were removed from the market—fenfluramine
and dexfenfluramine—was due to activation of the 5-HT2B recep-
tors expressed on cardiac valvular interstitial cells. By activating
the 5-HT2C receptor, lorcaserin is thought to decrease food intake
through the pro-opiomelanocortin (POMC) system of neurons.
Lorcaserin has undergone two randomized, placebo-controlled,
double-blind trials for efficacy and safety. Participants were ran-
domized to receive lorcaserin (10 mg bid) or placebo in the BLOOM
study and lorcaserin (10 mg bid or qd) or placebo in the BLOSSOM
study. All participants received diet and exercise counseling. Partic-
ipant numbers, eligibility, characteristics, and weight-loss outcomes
are displayed in

. Patients who were overweight or
obese had at least one coexisting condition (hypertension, dys-
lipidemia, cardiovascular disease, impaired glucose tolerance, or
sleep apnea)—medical conditions that are commonly seen in the
office setting. Intention-to-treat 1-year placebo-subtracted weight
loss was 3.6% and 3.0%, respectively, in the BLOOM and BLOSSOM
trials. Echocardiography was performed at the screening visit and..

SURGERY
Bariatric surgery (Fig. 395-2) can be considered for patients with
severe obesity (BMI, ≥40 kg/m2
) or for those with moderate obe-
sity (BMI, ≥35 kg/m2

) associated with a serious medical condition.
Weight-loss surgeries have traditionally been classified into three
categories on the basis of anatomic changes: restrictive, restrictive
malabsorptive, and malabsorptive.

More recently, however, the clin-
ical benefits of bariatric surgery in achieving weight loss and allevi-
ating metabolic comorbidities have been attributed largely to changes
in the physiologic responses of gut hormones, bile acid metabolism,
the microbiota, and in adipose tissue metabolism.

Metabolic effects
resulting from bypassing the foregut include altered responses of
ghrelin, glucagon-like peptide 1, peptide YY3-36, and oxyntomod-
ulin. Additional effects on food intake and body weight control
may be attributed to changes in vagal signaling.

The loss of fat
mass, particularly visceral fat, is associated with multiple meta-
bolic, adipokine, and inflammatory changes that include improved
insulin sensitivity and glucose disposal; reduced free fatty acid flux;
increased adiponectin levels; and decreased interleukin 6, tumor
necrosis factor α, and high-sensitivity C-reactive protein levels.


Restrictive surgeries limit the amount of food the stomach can
hold and slow the rate of gastric emptying. Laparoscopic adjustable
gastric banding is the prototype of this category. The first banding
device, the LAP-BAND, was approved for use in the United States
in 2001 and the second, the REALIZE band,
in 2007.

In contrast to
previous devices, these bands have diameters that are adjustable
by way of their connection to a reservoir that is implanted under
the skin. Injection of saline into the reservoir and removal of saline
from the reservoir tighten and loosen the band’s internal diameter,
respectively, thus changing the size of the gastric opening.

Although
the mean percentage of total body weight lost at 5 years is estimated
at 20–25%, longer-term follow-up has been more disappointing
leading to near abandonment of the procedure. In the laparoscopic
sleeve gastrectomy, the stomach is restricted by stapling and dividing
it vertically, removing ~80% of the greater curvature and leaving a
slim banana-shaped remnant stomach along the lesser curvature.
Weight loss after this procedure is superior to that after laparoscopic
adjustable gastric banding.


The three restrictive-malabsorptive bypass procedures combine
the elements of gastric restriction and selective malabsorption:
Roux-en-Y gastric bypass, biliopancreatic diversion, and biliopan-
creatic diversion with duodenal sw.

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most commonly undertaken and most accepted bypass procedure.
They are routinely performed by laparoscopy.


These procedures generally produce a 30–35% average total
body weight loss that is maintained in ~60% of patients at 5 years.
Significant improvement in multiple obesity-related comorbid
conditions, including type 2 diabetes, hypertension, dyslipidemia,
obstructive sleep apnea, quality of life, and long-term cardiovascu-
lar events, has been reported. A meta-analysis of controlled clinical
trials comparing bariatric surgery versus no surgery showed that
surgery was associated with a reduced odds ratio (OR) risk of global
mortality (OR = 0.55), cardiovascular death (OR = 0.58), and all-cause
mortality (OR = 0.70).


Among the observed improvements in comorbidities, the pre-
vention and treatment of type 2 diabetes resulting from bariatric
surgery has garnered the most attention. Fifteen-year data from the
Swedish Obese Subjects study demonstrated a marked reduction
(i.e., by 78%) in the incidence of type 2 diabetes development among
obese patients who underwent bariatric surgery.

Several random-
ized controlled studies have shown greater weight loss and more
improved glycemic control at 1 and 3 years among surgical patients
than among patients receiving conventional medical therapy. A
retrospective cohort study of >4000 adults with diabetes found that
overall 68.2% of patients experienced an initial complete type 2 dia-
betes remission within 5 years after surgery. However, among these
patients, one-third redeveloped type 2 diabetes within 5 years. The
rapid improvement seen in diabetes after restrictive-malabsorptive
procedures is thought to be due to caloric restriction, reduced insu-
lin resistance, and surgery-specific effects on glucose homeostasis
brought about by alteration of gut hormones.


The mortality rate from bariatric surgery is generally <1% but
varies with the procedure, the patient’s age and comorbid condi-
tions, and the experience of the surgical team.

The most common
surgical complications include stomal stenosis or marginal ulcers
(occurring in 5–15% of patients) that present as prolonged nausea
and vomiting after eating or inability to advance the diet to solid
foods.

These complications typically are treated by endoscopic bal-
loon dilation and acid suppression therapy, respectively. For patients
who undergo laparoscopic adjustable gastric banding, there are no
intestinal absorptive abnormalities other than mechanical reduction
in gastric size and outflow.

Therefore, selective deficiencies are
uncommon unless eating habits become unbalanced. In contrast,
the restrictive-malabsorptive procedures carry an increased risk
for micronutrient deficiencies of vitamin B12, iron, folate, calcium,
and vitamin D.

Patients with restrictive-malabsorptive procedures
require lifelong supplementation with these micronutrients.
Intraluminal Gastric Balloons Recently, the FDA approved two
gastric balloon devices for weight loss that are placed in the stom-
ach endoscopically.

The RESHAPE device consists of two silicone
balloons attached to a central silicone shaft, whereas the ORBERA
is a single-balloon device. Mean weight loss of 7.2 kg and 8.8 kg,
respectively, was seen for these devices in short-term pivotal trials.
Both systems are approved only for up to 6 months of use in adults
with a BMI of 30–40 kg/m2
. Adverse effects include nausea, vomit-
ing, and abdominal pain.

sibutramine.

Bulk agents . psychotherapy, liposuction, surgery,

  • laparoscopic adjustable gastric banding
  • Laparoscopic sleeve gastrectomy

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