Obesity

Contents:

• Definition of Obesity
• Quick facts
• Measurement of obesity
• Consequences
• Causes
• Treatment

Define Obesity/what is obesity?

Definition: It is a chronic disease of excess adipose tissue having multiple etiologies; genetic, environmental, behavioural and neurohormonal.

Obesity is a multifactorial , chronic disease characterised by an accumulation of visceral and subcutaneous fat, which promotes adipocyte dysfunction.

• More than 25% of adults in UK and over 40% of Americans are obese.
• Obesity is a major public health problem in higher income countries and an emerging health problem in lower income nations like India.
• According to WHO, greater then 1.9 billion adults were estimated to be overweight or obese globally in 2015 , of which 650 million were obese
• Obesity is associated with several of the most important diseases of humans like type 2 diabetes, dyslipidemia, cardiovascular diseases, hypertension and cancer.

• Central or visceral obesity, in which excess fat accumulates preferentially in the trunk and in the abdominal cavity (in mesentary and around viscera) is essential with a much higher risk for several diseases than in excess accumulation of subcutaneous fat

Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health.

Body Mass Index(BMI) has been used by WHO as a standard for assessing obesity for over 30 years. BMI is calculated by dividing an individual’s weight in kilograms by the square of his or her height in metres.

BMI = Weight(kg)/Height(m)^2

BMI does not take into account factors such as muscularity, frame size and bone density.

BMI has its own drawbacks, they are as follows:

• BMI can be particularly inaccurate for those who are fit and have a high muscle mass.
• BMI can occasionally overestimate (as in body builders) or underestimate (as in elders) total body fat.

• The normal range of BMI differs for different countries due to differences and genetic backgrounds.
• There are other methods to assess obesity such as:

1. Ideal body weight for height
2. skin fold thickness
3. waist circumference and waist to hip ratio

• However, BMI isthe clinically easiest system to use employing the simply measured parameters of height and weight.

• Obesity is associated with significant increase in both morbidity and mortality.
• over 200 health conditions ranging from hypertension, CAD to thromboembolic and skin disorders can be more prevalent in patients with Obesity.
• The following is the list of risks associated with obesity:

1. Hypertension
2. Type 2 Diabetes mellitus and Insulin resistance
3. CAD
4. stroke
5. Breast, endometrial and colon cancer
6. varicose veins
7. Depression
8. Cholelithiasis
9. sleep apnea syndrome
10. Osteoarthritis
11. Increase in all cause mortality
12. Deep vein thrombosis

• The etiology of obesity is complex and incompletely understood.
• Genetic, environmental and psychological factors are involved.
• In simple terms, obesity is a disorder of energy homeostasis.
• The two sides of energy equation, intake and expenditure are finely regulated by neural and hormonal mechanisms so that body weight is maintained within a narrow range for many years.
• Hypothalamus is the master regulator of energy homeostasis.

The Hypothalamus, Stomach and Adipocyte all play important roles in this complex process. Release of hormone Ghrelin from gastric oxyntic cellstriggers food intake. This compound stimulates the release of neuropeptides in the ‘Hunger Centre of Hypothalamus’ , increasing caloric consumption.

To signal adequate caloric load, the adipocyte releases hormone leptin, which activates satiety centre of hypothalamus and results in decreased food intake.

The stomach, adipocyte and hypothalamus, therefore constitute an intricate hormonal axis that helps to control energy homeostasis via appetite regulation. Defects within this axis can lead to energy imbalance with important metabolic consequences.

For example; leptin receptor deficiency results in a loss of satiety signal and development of obesity, likewise Ghrelin overproduction contributes to the hyperphagia and obesity seen in patients with Prader-Willi syndrome.

The above mentioned mechanism comes es under genetic influence causing obesity.

• Enviromental causes of obesity can be:

1. Greater food availability
2. Sedentary lifestyle

list of causes of Obesity:

simple Obesity Secondary Obesity

• Physical inactivity. Hypothyroidism
• Eating habits. Cushing syndrome
• Psychological factors. Hypothalamic disorder

(overeating may be a symptom of depression, anxiety and frustration)

• Genetic factors. Medications like valporic acid,

antidepressants, corticosteroids etc

Managing overweight and obese patients requires a variety of skills of a various health care practitioners (physicians, nutritionists, registered ditiations, psychologists and exercise physiologists) working as a multi disciplinary team to help patients achieve the changes they need over the long-term.

Treatment of overweight and obese people fall in 3 broad categories:

1. Behaviour modification(diet and exercise)
2. Pharmacotherapy
3. Surgical intervention

All three therapies are able to induce a degree of weight loss although variable. Only bariatric surgery, however, has been successful in helping people lose a significant amount of weight without regain.

Behaviour modification: It helps patients change the mall adaptive eating behaviour leading to obesity.

• The goal of behavioural treatment can include self monitoring of intake, control of emotional eating, stimulus control strategies , problem solving and relapsed prevention.
• Self-monitoring is the cornerstone to a successful behaviour therapy.
• Obese individuals often underestimate their food intake. Data have shown that individuals who record they are daily intake lose more weight than those who do not record their food intake.
• Strategy should be applied that help patients control their environment. For example; to stock their homes with healthier food options, avoiding eating while watching television.
• 2 main modifications are recommended for patients suffering from obesity.

1. Reduction in energy intake.
2. Augmentation in energy expenditure (exercise)

• Physical activity offers several advantages for patients trying to achieve and maintain wheat loss. It is useful for long-term weight maintenance and helps preserve lean body mass.

The American College of sports medicine recommends 150 minutes of moderate intensity aerobic physical activity (such as Tennis or brisk walking) per week, 75 minutes of vigorous intensity, aerobic exercise (such as jogging or swimming laps) per week or an equivalent combination of moderate and vigorous intensity aerobic activity. Resistance training is also recommended twice per week.

Pharmaco therapy can enhance weight loss in selected obese patients , and they should only have a role as a part of comprehensive weight management program that includes behavior therapy, diet and physical exercise.

• Dietary therapy, physical exercise and behaviour modification should be considered before using drugs.
• Drugs may be used if BMI > 30kg/m^2
• Drugs may also be used if BMI is 27 to 30 kg per metre square and the patient has an increase the risk of:

1. Asian ethnicity
2. overweight/obesity related disease likely to improve with weighloss, such as type 2 diabetes, obstructive sleep apnea and dyslipidemia of obesity.

• The patient should be monitored for safety throughout.
• If the patient has not lost at least 5% of their body weight by week 12 using drugs, consider for discontinuation.
• Each and every drug for weightloss comes with its own side effects.
• The following are the drugs for weightloss:

1. Sibutramine

Along with lifestyle modification, it provides a mean weight loss of approximately 4.5 kg at 1 year.

Side effects include dry mouth, constipation, headache and insomnia.

Produces a dose related increase in heart rate and may increase blood pressure and cardiovascular events.

Withdrawn due to cardiovascular effect.

2. Orlistat

Produces favourable changes in total cholesterol cholesterol levels, free fatty acids, HBA1C and insulin sensitivity.

Side effects include oily stools , faecal urgency , diarrhea, flatulence , fecal incontinence , bloating and abdominal pain that can be minimized by a low fat diet.

3. Phentermine – Topiramate

This combination has been approved for use in obese patients, along with dietary restrictions and lifestyle modification.

Topiramate is contradicted in pregnancy; hence it is recommended that pregnancy testing is done before starting the medication and then every month to ensure patients are not pregnant while taking the medication.

This combination worsens depression and suicidal ideation; It can also cause mood disorders, anxiety and insomnia.

Phentermine, approved in 1959, is the most commonly prescribed antiobesity medication.

There are other antiobesity medications approved by FDA(food and drug administration):

– a fixed dose of Naltrexone SR and buproprion SR

– Liraglutide

– Lorcaserine

• Surgery remains the only proven modality , effective in inducing and maintaining weight loss and in reducing lifetime obesity related morbidities and mortality.
• There is a criteria established in 1991 by NIH Concensus Development Conference by which patients undergo consideration for operative treatment of obesity: individuals with a BMI of 40kg/m^2 or greater and individuals with a BMI of 35 to 40 kg/m^2 with significant obesity related comorbidities(comobidity: Simultaneous presence of two or more diseases or medical conditions in a patient)
• It was also added in a 1998 NIH guidelines that potential surgical candidates must have failed at a non operative attempts at weight loss. They also must be psychologically stable and willing to follow post operative diet instructions. Finally, they must not have any medical (I.e., endocrine) cause for their obesity.
• Bariatric procedures induce weight loss by decreasing energy intake.

Types of weight reduction surgeries:

1. Restrictive procedures

2. Adjustable gastric banding (AGB)

3. Sleeve gastrectomy (SG)

4. Malabsorptive procedures

5. Biliopancreatic diversion with or without duodenal switch

6. Combination of malabsorption and restriction

7. Roux-en-Y gastric bypass

Currently, the 4 most common bediatric operations in the United States are sleeve. Gastrectomy , Roux-en-Y gastric bypass, Adjustable gastric banding and Biliopancreatic diversion with or without a deodorant switch.

1. Sleeve Gastrectomy:

• SG is currently the most common operative intervention, recently having surpassed RNYGB for morbid obesity in the United States.
• In this procedure, the surgeon removes approximately 85% of stomach laproscopically, so that the stomach takes the shape of a tube or ‘sleeve’.
• This procedure is not reversible.
• SG results in excellent weight loss and commorbidity reduction that exceeds or is comparable to that of other accepted bariatric procedures.
• Weight loss in the first 2 years is from 60% to 75% of excess body weight (EBW). Long-term data is limited, but the 5 and 10 year follow-up data have demonstrated the durability and safety of the SG procedure.

2. Biliopancreatic diversion with or without duodenal switch:

• Here, the stomach is reduced in size, the gall bladder is removed, the proximal duodenum is divided and reanastomosed to more distal small bowel and a short common channel is created via jejunoileostomy.
• Weight loss is predominantly secondary to malabsorption, complications related to malnutrition are more frequent in this procedure.

3. Roux-en-Y gastric bypass:

• RNYb remains the gold standard of weight loss procedures, although the SG might replace it in near future.
• Weight loss averages from 60% to 80% EBW within 2 years. Nutritional problems tend to be less severe than those of BPD or BPD/DS. Evidence of long-term weight loss of 60% of EBW up to 15 years after the procedure exists.

Complications of bariatric operations:

Complication of bariatric operations may occur early, that is, occurring preoperatively or before the patient is discharged from the hospital, Or late, that is, occurring after the patient has been discharged.

Early complication. Late complication

1. Anastomotic leak. Nutritional disturbances.
2. Deep venous thrombosis Marginal ulcers and

or pulmonary emboli. anastomotic strictures

3. Bleeding. Internal hernia

4. Infection. Afferent limb syndrome

5. Splenic or visceral injury. Cholelithiasis, band

slippage, band erosion,

Esophageal dilation.