World Gastroenterology Organisation practice guidelines: Obesity

Introduction and summary 

Areas of uncertainty and key management points 

Key management points 

•The first treatment step is the basis for every subsequent step and consists of a diet, a less sedentary lifestyle, exercise, and behavioral modification. If weight loss of 5–10% is not achieved within 6months, the next step is the same basic treatment combined with medication. The last step is again a diet, a less sedentary lifestyle, exercise and behavioral modification, but now combined with bariatric surgery.

•Obesity requires long-term care, and it is important that management should be provided in a multidisciplinary environment with support from physicians, medical specialists (internists), dietitians, and surgeons.

•Providing education and information for children may be the best and least costly way of controlling obesity in the longer-term.

Definitions 

•Body mass index (BMI): weight (in kilograms) divided by the square of the individual’s height (in meters).

•The International Obesity Task Force (IOTF) definition of obesity (based on Caucasians with a “western” lifestyle) sets cut-off points of 25kg/m2 for adult excess weight and 30kg/m2 for obesity. These BMI cut-off points are considered to have a more international basis than other definitions.

•The BMI index ranges for children and teenagers should take the normal differences in body fat between boys and girls and differences in body fat at various ages into account:United States Centers for Disease Control and Prevention (CDC) definition:

−BMI⩾95th percentile for age=“overweight”

−BMI between the 85th and 95th percentiles=“at risk of overweight”

−European Childhood Obesity Group classification:

−BMI⩾85th percentile for age=“overweight”

−BMI⩾95th percentile for age=“obesity”

Epidemiology (Table 1, Fig. 1) 

Table 1. Global epidemiology, 2005–2015.

	2015	The World Health Organisation (WHO) projects that by 2015, approximately 2.3 billion adults will be overweight and more than 700 million will be obese
	2008	A report in the Journal of the American Medical Association (JAMA) shows that overall, in 2003–2006:
		•11.3% of children and adolescents aged 2–19years were at or above the 97th percentile of the 2000 BMI-for-age growth charts (extreme obesity)
		•16.3% were at or above the 95th percentile (obese)
		•31.9% were at or above the 85th percentile (overweight)
		•Prevalence estimates varied by age and by ethnic group
		•Analyses of the trends in high BMI-for-age showed no statistically significant trend over four periods studied (1999–2000, 2001–2002, 2003–2004, and 2005–2006), for either boys or girls
		Today, the mean BMI has increased and the most obese individuals have become much more obese, so that the curve of the normal distribution has shifted to the right
	2005	•WHO data show that in 2005, approximately 1.6billion adults (aged 15 or over) were overweight and that at least 400million adults were obese
		•At least 20million children under the age of 5years were overweight globally in 2005
		•Obesity has become an epidemic condition
		•In the United States, obesity among adults increased from 15.3% in 1995 to 23.9% in 2005

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Fig. 1. Body mass index (BMI) data by country: percentages of adults with a normal BMI.

Metabolic syndrome (Table 2, Table 3) 

Obesity plays a central role in the metabolic syndrome. Especially in non-Caucasian populations, genetic predisposition or adverse events in early life may contribute to the insulin resistance and adverse body-fat patterning seen in the metabolic syndrome and its related complications.

Table 2. Features of metabolic syndrome.

	•Hyperinsulinemia, insulin resistance, glucose intolerance
	•Type 2 diabetes mellitus
	•Hypertension
	•Atherogenic lipoprotein phenotype
	•Prothrombotic states
	•Increased risk of atherosclerotic cardiovascular disease

Table 3. Biological functions and health consequences.

Source: Grundy et al., Circulation 2005;112:2735–52.

	Body fat deposition	→	Excess weight
	↕
	Insulin sensitivity	→	Metabolic syndrome
	↕
	Regulation of blood glucose levels	→	Diabetes

Table 4 lists the National Cholesterol Education Program (NCEP) criteria for metabolic syndrome, following on from the WHO criteria, dating back to 2002–2003. In 2005, the International Diabetes Federation (IDF) published new criteria. Table 5 presents the differences between the three existing definitions.

Table 4. Clinical diagnosis of the metabolic syndrome: three or more of the following abnormalities.

Source: Grundy et al., Circulation 2005;112:2735–52.

	Component	Trait	Defining value
	Abdominal obesity	Waist circumference	F: >80cm
			M: >94cm
	Atherogenic dyslipidemia	Triglycerides	>1.70mmol/L
		HDL cholesterol	F: <1.30mmol/L
			M: <1.04mmol/L or drug treatment
	Elevated BP	Ambulatory BP	Systolic ⩾130mmHg
			Diastolic ⩾85mmHg or drug treatment
	Elevated FPG	FPG	⩾100mg/dL or drug treatment

BP, blood pressure; F, female; FPG, fasting plasma glucose; HDL, high-density lipoprotein; M, male.

Table 5. Definitions of metabolic syndrome.

	WHO 1998	NCEP 2002–2003	IDF 2005
	Insulin resistance (hyperinsulinemic clamp, diabetes, IGTT)		Waist circumference
	Plus two or more of:	At least three of:	Plus two or more of:
	W/H ratio	Waist circumference
	Triglycerides ⩾1.7	Triglycerides ⩾1.7	Triglycerides ⩾1.7
	Or HDL cholesterol	HDL cholesterol	HDL cholesterol
		Fasting glucose >6.1	Fasting glucose >5.6
	RR >140/90	RR >130/85	RR >130/85
	Or Rx for microalbuminuria	Or Rx	Or specific treatment

BMI, body mass index; HDL, high-density lipoprotein; IDF, International Diabetes Foundation; IGTT, intravenous glucose tolerance test; NCEP, National Cholesterol Education Program (Adult Treatment Panel III); RR, Riva–Rocci (blood pressure); Rx, drug prescription; W/H, waist/height; WHO, World Health Organisation.

Patient history 

•Comprehensive nutritional history: patterns of food intake (including binge eating).

•Comprehensive weight history:

—Weight gain and maximum body weight.

—Weight trends.

•Family history:

—Excess weight and obesity.

—Premature heart disease (myocardial infarction or sudden death of father or other male first-degree relative ⩽55years of age, or of the mother or other female first-degree relative ⩽65years).

•Physical activities.

•Medication history:

—Corticosteroids.

—Antipsychotic agents.

—Antidepressants.

—Oral contraceptives.

—Oral hypoglycemic agents.

—Other drugs associated with weight gain.

•Cigarette smoking.

•Coexisting conditions:

—Sleep apnea: very loud snoring, cessation of breathing during sleep, often followed by a loud clearing breath and brief awakening.

•Stress incontinence.

•Patient’s motivation and willingness to reduce weight:

—Previous weight loss efforts.

—Perceived obstacles to successful weight management.

Physical examination 

Percentage of excess weight/obesity:

•Body weight and height.

•Percentage of body fat.

•Body mass index (Table 6):

—Most practical way to evaluate the overall degree of excess weight.

—BMI ⩾30 is associated with increased risks of death from all causes and from cardiovascular disease.

—Most patients with a BMI ⩾30, and many with a BMI of 25–30, have at least one coexisting condition.

Table 6. The international classification of adult underweight status, overweight status, and obesity relative to body mass index (BMI).

	Classification	Principal BMI cut-off points (kg/m2)
	Underweight	<18.50
	Severe thinness	<16.00
	Moderate thinness	16.00–16.99
	Mild thinness	17.00–18.49
	Normal range	18.50–24.99
	Overweight	⩾25.00
	Pre-obese	25.00–29.99
	Obese	⩾30.00
	Class I	30.00–34.99
	Class II	35.00–39.99
	Class III	⩾40.00

•Waist circumference:

—Most practical measure of central adiposity – a good indicator of abdominal fat.

—Predicts the risk for developing heart disease and other diseases

—Increased risk >100cm (>40inches) in men and >87.5cm. (>35inches) in women.

—Measurement is not particularly useful in persons with a BMI >40.

—Waist circumference is an independent predictor of patient outcome.

•Skinfold thickness.

Assessment for accompanying conditions 

•Diabetes:

—Presence of acanthosis nigricans as a sign of insulin resistance

—Impaired fasting glucose (IFG), between 5.55mmol/L and 6.94mmol/L. IFG is an independent risk factor for cardiovascular (macrovascular) disease and is a risk factor for type 2 diabetes.

•Hypertension:

—Systolic blood pressure of ⩾140mmHg or diastolic blood pressure ⩾90mmHg.

—Current use of antihypertensive agents.

•Coronary artery disease:

—Baseline electrocardiogram.

—History of myocardial infarction.

—Angina pectoris.

—Coronary artery surgery.

—Coronary artery procedures (e.g., angioplasty).

•Presence of other atherosclerotic diseases:

—Peripheral arterial disease.

—Abdominal aortic aneurysm.

—Symptomatic carotid artery disease.

•Musculoskeletal disease: osteoarthritis.

•Other obesity-associated diseases:

—Cancer screening.

—Pulmonary hypertension.

—Gynecological abnormalities (e.g., menorrhagia, amenorrhea).

—Gallstones.

Additional diagnostic tests 

Baseline and diagnostic laboratory tests:

Laboratory studies, to be performed as guided by the initial evaluation:

•Glycemia/insulinemia – blood glucose control:

—Fasting plasma glucose.

—Glycosylated hemoglobin.

—75g oral glucose tolerance test (2-h plasma glucose).

•Cholesterol – targets based on risk factors for coronary heart disease (CHD):

—Low-density lipoprotein (LDL) target levels:0–1 risk factors: 4.16mmol/L.2 risk factors: 3.38mmol/L.Patient has CHD or equivalent: 2.60mmol/L.Patient at high risk: 1.82mmol/L.

•Non-HDL target levels:0–1 risk factors: 4.94mmol/L.2 risk factors: 4.16mmol/L.Patient has CHD or equivalent: 3.38mmol/L.

—Triglyceride level.

•Liver function:

—Aspartate aminotransferase.

—Alanine aminotransferase.

—Alkaline phosphatase.

•Obstructive sleep apnea: nocturnal pulse oximetry or formal sleep study.

•Heart function:

—Chest film.

—Electrocardiogram.

—Additional diagnostic studies.

•Cardiovascular assessment.

•Cancer screening.

•Screening for secondary causes:

—Cushing’s syndrome.

—Hypothyroidism.

—Hypothalamic disease.

—Leptin deficiency.

Diets 

A recent meta-analysis summarized current outcomes (Table 7).

Table 7. Meta-analysis of diets in maintenance of weight loss: 29 studies with a follow-up period of at least 2years.

Source: Anderson et al., American Journal of Clinical Nutrition 2001;73:579–83.

		Follow-up (y)	Studies (n)	Weight loss (kg)	WLM (kg)	WLM (%)	Weight reduction (%)
	All	4.5	13	14.0	3.0	23.4	3.15
	Men	4.4	5	18.3	4.7	30.5	4.48
	Women	4.4	6	16.6	4.66	23.6	4.67
	VLCD	4.5	4	24.1	7.05	29.4	6.59
	HBD	4.5	8	8.8	1.99	17.8	2.11
	Lower exercise	2.7	6	22.0	7.47	27.2	6.66
	Higher exercise	2.7	6	20.9	14.99	53.8	12.49

HBD, hypoenergetic balanced diet; VLCD, very low-calorie diet; WLM, weight loss maintenance.

The long-term efficacy of diets requires further study; currently available results are listed in Table 8.

Table 8. Long-term efficacy of diets in 17 studies including 3030 patients, with a follow-up period of at least 3years and an attrition rate of less than 50% – median follow-up 5y (range 3–14y) in 2131 patients (70%) and with maintenance of all weight loss or at least 9–11kg of initial weight loss.

Source: Ayyard and Anderson, Obesity Review 2000;1:113–9.

			Range
	Initial weight loss (median)	11kg	4–28kg
	Successful weight maintenance	15%	0–49%
	Influence of initial treatment
	Diet + group therapy	27%	14–31%
	Diet alone	15%	6–28%
	Diet + behavioral therapy	14%	0–49%
	Influence of energy level of initial diet
	VLCD (300–600kcal)	14%	6–49%
	Conventional diet (800–1800kcal)	18%	0–31%
	Influence of intensity of follow–up
	Active approach	19%	13–49%
	Passive approach	10%	0–31%
	VLCD + behavioral therapy + active follow-up	38%	27–49%

VLCD, very low-calorie diet.

The minimum energy required by a normal-weight adult who stays in bed is approximately 0.8kcal/min (1150kcal/day).

•This maintains body temperature, function of the heart and other organs, and tissue repair.

•High levels of physical activity can increase energy expenditure 4–8-fold.

•As a guideline, a normal adult needs approximately 22–25kcal/kg nutrient intake to maintain 1 kg of body weight.

For weight loss to occur, energy intake must be less than energy expenditure.

•Predicted weight loss: 0.5–1.0kg/week, based on a calorie deficit of 500–1000kcal/day with no changes in physical activity.

•In general, diets <800kcal/day are not recommended.

Reduced-calorie diets include those specifying caloric intakes:

• Very low (less than 800 kcal/day).

—To be used only when more rapid weight loss is needed.

—Medical monitoring is necessary.

•Low (800–1500kcal/day).

•Moderate (about 500kcal less than typical daily intake).

•Lowering energy intake either by reducing the appetite or by lowering the energy density of the foods eaten is able to facilitate body weight reduction – more controlled intervention trials are needed to assess whether the effects on body weight are also sustained in the longer-term.

Low-carbohydrate diets 

These show better 6-month results than with low-fat diets, but the differences are no longer significant at 12months.

•<60g of carbohydrates daily.

•Many diets (such as the Atkins and South Beach diets) start with <20g of carbohydrates daily and gradually increase the quantity.

High-fiber diets (legumes, vegetables, wholemeal diets) 

Potential adjuncts to effective dietary management 

Physical activity 

•Exercise is recommended as a weight loss intervention, particularly when combined with dietary change.

•The combination of increases in physical activity and caloric restriction results in more weight reduction and body composition changes (fat versus lean mass) than diet or physical activity alone.

•Exercise is associated with improved cardiovascular disease risk factors even if no weight is lost:

—It reduces abdominal adipose tissue and improves insulin resistance.

—It increases plasma high-density lipoprotein (HDL) cholesterol levels and reduces triglyceride levels and blood pressure.

—Resistance training may be particularly beneficial in modifying body composition.

—Adults should set a long-term goal of a minimum of 30min of moderate-intensity physical activity per day.

—Exercise is a predictor of weight maintenance.

Behavioral modification and counseling 

Behavioral therapy (Table 9) may result in an 8–10% loss in body weight at 6months.

Table 9. Behavioral therapy: studies published 1990–2000.

Sources: Wing RR, “Behavioral approaches to the treatment of obesity,” in: Bray GA, Bouchard C, James WPT, editors, Handbook of obesity, 2nd ed. (New York: Dekker, 1998), pp. 855–74; McTigue et al., Annals of Internal Medicine 2003;139:933–49; Kushner, Surgery for Obesity and Related Diseases 2005;1:120–2.

	Duration of behavioraltherapy (months)	Studies (n)	Average weight loss (kg)
	5	12	10.4 (11.1%)
	18	7	8.2 (9.5%)
	24	2	7.1 (7.0%)
	12	USPSTF RCTs	3.7–5.7

RCT, randomized controlled trial; USPSTF, United States Preventive Services Task Force.

Behavioral treatment is generally provided in individual or small-group sessions held weekly for 6months. Its key features include:

Introduction 

Generally, drugs only play a role in settings in which resources are not a key issue. The medicines available for combating obesity are limited in number and effectiveness (Table 10). Nevertheless, weight loss medications can help patients adhere to lifestyle advice, and may result in clinically significant and meaningful improvement of symptoms, risk factors, and quality of life. An understanding of the benefits and risks associated with each of the available drugs is required in order to allow appropriate selection and use of weight-management drugs.

Table 10. Drugs prescribed for weight loss.

	Drug Generic name, proprietary name (manufacturer)	FDA approval	ScheduleIV controlled substance	Mechanism	Dosage	Weight loss beyond that with placebo	Side effects	Comments
	Phentermine E.g.: Adipex-P (Gate); Fastin (Hi-Tech); Ionamin (Celltech)	Approved for weight loss	Yes	Sympatho-mimetic mechanism	15, 30, or 37.5mg/day	4%	Dry mouth, insomnia, dizziness, mild increase in blood pressure (rarely more severe) and heart rate	Insufficient data from RCTs; increased risk of pulmonary hypertension probably not a concern; pregnancy category C; available as generic; requires blood-pressure monitoring
	Diethylpropion Tenuate (Sanofi-Aventis)	Approved for weight loss	Yes	Sympatho-mimetic mechanism	25mg 3× a day or 75mg controlled-release daily	3%	Dry mouth, insomnia, dizziness, mild increase in blood pressure and heart rate	Has minimal effect; excreted by kidneys; pregnancy category B; requires blood-pressure monitoring
	Sibutramine Meridia (Abbott)	Approved for weight loss	No	Inhibition of norepinephrine and serotonin reuptake	5, 10, or 15mg/day	5%	Mild increase in blood pressure and heart rate (rarely more severe), palpitations	Pregnancy category C; requires blood-pressure monitoring
	OrlistatXenical (Roche); Alli (GlaxoSmithKline)	Approved for weight loss	No	Lipase inhibition in gastrointestinal tract	120mg 3× a day (Xenical) or 60mg 3× a day; available over the counter (Alli)	3%	Oily spotting, flatus with discharge, fecal urgency	Side effects decrease with time; may work better when fat remains in diet, but this results in increased side effects; decreases LDL cholesterol; pregnancy category B
	Rimonabant Acomplia (Sanofi-Aventis)	Not approved	n.a.	Inhibition of cannabinoid receptor CB1	20mg/day	5%	Nausea, diarrhea, anxiety, depression	Prototype of a new class of prescription drugs. No longer available in Europe

FDA, Food and Drug Administration (United States); RCT, randomized controlled trial; LDL, low-density lipoprotein; n.a., not available. Schedule IV controlled substance: so listed under the Controlled Substances Act (1970) in the United States.

The drug trials have generally only covered short periods, and no studies of long-term administration have been published. Most studies have reported treatment periods of 1–2years. All medication is interrupted after 1–2years, and as obesity is an incurable disease, it recurs in the same way as diabetes insulin treatment is stopped.

In randomized trials of medications approved by the United States Food and Drug Administration (FDA) combined with changes in lifestyle, in comparison with placebo and changes in lifestyle alone, it was found that the reduction from the initial weight was 3–5% greater with the medications.

•Reductions in risk factors for cardiovascular disease are generally related to the amount of weight reduction.

•The criteria for pharmacologic therapy in combination with lifestyle approaches to facilitate weight loss and prevent weight regain are:

—BMI>30.

—BMI>27 plus coexisting conditions.

Phentermine and diethylpropion 

•Randomized trials show a 3–4% greater weight reduction in comparison with placebo. (The drugs are no longer available in Europe.)

•Adrenergic stimulants enhance norepinephrine release in certain brain regions, leading to reduced food intake, but only limited data are available on efficacy and safety.

•Blood pressure should be closely monitored in patients who have prehypertension or are receiving treatment for hypertension.

•There is a potential (although low) risk of dependency and drug abuse (the agents are classified by the Drug Enforcement Agency in the United States as Schedule IV controlled substances).

•Approved for short-term use only; limited data suggest these stimulants may be effective for >10years.

Sibutramine 

•Sibutramine is modestly effective in reducing weight, with differing effects on cardiovascular risk and various adverse effect profiles.

•Treatment with sibutramine reduced body weight but not blood pressure.

•Randomized trials have shown a 5% greater weight reduction in comparison with placebo (but only short-term trials have been carried out; administration of the drug for more than 18months is not allowed).

•The drug is a serotonin–norepinephrine reuptake inhibitor that reduces appetite. Combination with lifestyle modification resulted in more weight loss at 12months (combination: 12.1kg; sibutramine alone 5.0kg; lifestyle intervention alone 6.7kg).

•Patients who had the greatest initial weight loss and were most physically active were most likely to maintain weight loss successfully.

•Common side effects: hypertension and tachycardia (related to adrenergic properties).

Orlistat 

•Orlistat is modestly effective in reducing weight, with differing effects on cardiovascular risk and various adverse effect profiles.

•In patients with essential hypertension, therapy with a weight loss diet or orlistat treatment reduced body weight and blood pressure.

•One study of orlistat plus lifestyle changes reported a weight reduction of approximately 3% more than with lifestyle intervention alone.

•The drug is a triacylglycerol lipase inhibitor and causes a 30% reduction in dietary fat absorption in the intestinal lumen.

•It is available over the counter at lower dosages in the United States (60mg, three times a day).

•It has been shown to result in about 2% more weight loss in comparison with placebo over a period of 4–24months.

•The pharmacologic effect depends on the presence of dietary fat, but a low-fat diet is recommended for patients receiving orlistat.

•Major side effects (usually short-lived) include oily spotting, flatus with discharge, and fecal urgency.

Rimonabant 

•Rimonabant administration produces modest weight loss of approximately 5% after 1year.

•The drug is a selective cannabinoid receptor CB1 blocker. The cannabinoid system contributes to the regulation of food intake, energy balance, and body weight.

•Modest amounts of weight loss may still be potentially beneficial.

•It is a new medication; better-quality studies with longer follow-up periods after treatment are needed before definitive recommendations can be made.

•It has been approved for the treatment of obesity in most of Europe and in Mexico and Argentina.

•It has not approved by the FDA due to concerns about side effects (including depression, anxiety, nausea and diarrhea, suicidal ideation, and suicide).

•In Europe, it is contraindicated in patients with severe depression and/or patients receiving treatment with antidepressive medications.

•It is not recommended for patients with other untreated psychiatric conditions.

•It is only allowed to be taken for a maximum of 2years.

Other drugs 

Intragastric balloon 

•A soft, saline-filled balloon is placed in the stomach endoscopically. It promotes a feeling of satiety and restriction.

•Obesity treatment with an intragastric balloon (IGB) itself, and the technique of positioning the balloon, appear to be safe.

•Placement is temporary (6months) and the method can be used prior to surgery in patients with morbid obesity.

•There appears to be little additional benefit of the intragastric balloon in relation to weight loss.

•IGB placement is reported to enhance motivation and encourage patients to change eating habits, following a well-organised diet and a program of behavioral modification. IGB may serve as an adjuvant factor in achieving and maintaining weight loss.

•Balloon treatment is permitted for a maximum period of 6months; removal of the balloon leads to recurrence of the disease.

Liposuction 

Introduction and key points 

It is difficult to compare different treatment options with surgery, as there have been few trials. Most results reported for diets and medications are short-term results. Although there are some data for medication that show results up to 2years, a proper comparison of different options would need to include 5-year or even 10-year results when available or state that there are no long-term results. Studies of surgical treatment do report long-term results, with follow-up periods of 1, 3, 5, and even 10years in some instances. Larger numbers of randomized studies using intention-to-treat analysis are needed.

The type of surgical intervention used depends on BMI and available resources. Adjustable gastric bands are the least invasive, safest, and most effective intervention and this is therefore probably the preferred surgical approach. When finances do not permit this approach, a gastric bypass is the next best operation. For patients with a BMI> 60, gastric bypass is the best surgical procedure, although there have been some reports that gastric bands are also effective. However, the choice of surgery should always take account of individual circumstances and can never be based on BMI alone.

Bariatric surgical procedures 

Bariatric surgical procedures reduce caloric intake by modifying the anatomy of the gastrointestinal tract. In the United States, the Roux-en-Y gastric bypass (open or laparoscopic) is the most commonly used operation. Bariatric operations can be classified into three types: restrictive procedures, malabsorptive procedures, and combined restriction–malabsorption procedures.

Restrictive procedures limit intake by creating a small gastric reservoir with a narrow outlet to delay emptying. These include:

•Gastric stapling (gastroplasty) – a recently developed method involving vertical restrictive (sleeve) gastrectomy (Fig. 2b). Partial gastric resection leaves a narrow tube of stomach as an alimentary conduit.

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Fig. 2. Classification of bariatric surgery.

•Adjustable gastric banding (Fig. 2a). This operation is performed laparoscopically and has been in use since 1995. It includes insertion of a subcutaneous reservoir. The extent of gastric restriction can be adjusted using injections of saline into the reservoir.

Malabsorptive procedures bypass varying portions of the small intestine, where nutrient absorption occurs.

Combination restriction–malabsorption procedures:

Combination procedures are sometimes performed as staged operations, with restriction followed by a Roux-en-Y procedure after initial weight loss has made surgery less difficult and reduced the operative risk.

Contraindications, associated risks, and complications 

Contraindications:

Mortality risks associated with bariatric surgery:

Perioperative complications:

Postoperative gastrointestinal complications:

Psychosocial factors have also been associated with a suboptimal surgical outcome:

Patients often require readmission or reoperation for complications or treatment of coexisting conditions. The risks require a multidisciplinary assessment including the following fields:

Results 

Patient outcome:

•The potential benefit of bariatric surgery for patients with mild obesity (BMI30–35) remains unclear. One randomized study reported significant benefits of surgery using an adjustable gastric band in comparison with medical therapy and behavior modification.

•The safety and efficacy of laparoscopic adjustable gastric banding (LAGB) have been demonstrated as a surgical therapy for morbid obesity in the short-term. Recent research on LAGB with the Swedish Adjustable Gastric Band (SAGB) shows that it is effective in achieving a mean sustainable weight loss of >50% at 8years after surgery, with an acceptably low morbidity rate.

•It is uncertain whether patients with extremely severe obesity are appropriate candidates for bariatric surgery.

—The operative risk may be greater for these patients, and surgical access may be difficult to impossible. Mortality rates may be higher among patients with a BMI⩾70.

—In the obese, bariatric surgery may be risky, but the risk of not reducing their weight may well be greater than the risks of the operation. This will continue to be an area of uncertainty until the results of further trials become available.

•The effectiveness of procedures varies and there are limited long-term outcome data:

—No large, randomized trials have compared current bariatric surgical techniques with medical management of severe obesity.

—A 2005 Cochrane Review suggests a typical weight loss of 20–50kg (44–110lb) with various bariatric procedures, in comparison with a modest weight gain in medically treated patients.

—The Swedish Obese Subjects (SOS) trial showed weight changes that were significantly greater in the surgical group than in the control group. However, the gain in life expectancy observed in the SOS study was modest.

—In general, weight loss with malabsorptive procedures tends to be greater than weight loss with solely restrictive procedures.

—Improvement in obesity-associated conditions – including diabetes, hyperlipidemia, hypertension, and sleep apnea – is reported after bariatric surgery.

—The SOS data suggest that some of these benefits, although still significant, are less marked at 10 years than at 2 years.

Management of obesity 

Treatment outcome 

General:

•A 5–10% reduction in weight may be sufficient for favorable modification of waist circumference, blood pressure, circulating cytokines, and (variably) fasting levels of glucose, triglycerides, and HDL cholesterol.

•A change in the treatment regimen should be considered if weight loss is less than 5% in the first 6months.

•Willingness to achieve weight reduction is important in predicting success.

Lifestyle intervention. Studies have shown that in comparison with standard care, lifestyle intervention:

•Significantly reduces body weight and cardiovascular risk factors.

•Has favorable effects, which are maintained for up to 3years.

Physical activity without a reduced calorie intake leads to limited weight loss results.

Treatment combinations. Dietary and lifestyle interventions, along with pharmacologic weight loss treatment, provide modest weight loss and may improve markers of cardiovascular risk factors, although these benefits occur mainly in patients with cardiovascular risks.

Maintenance of weight reduction 

The body has multiple mechanisms for modifying the energy balance to reestablish the original body weight. Weight loss induces a reduction in energy expenditure, hindering maintenance of weight loss. Failure to maintain weight loss is a common problem.

While short-term weight loss depends on caloric restriction, maintenance of weight loss mostly depends on the level of physical activity. For most people, long-term success is still difficult to achieve and current therapies for obesity do not provide sufficient support for patients in adhering to the required lifestyle changes.

Predictive factors for maintaining weight loss include:

•Eating a low-fat, fiber-enriched, protein-rich diet.

•Frequent self-monitoring of body weight and food intake.

•High levels of physical activity.

•Long-term patient–provider contact.

•Weight loss of more than 2kg in 4weeks.

•Frequent/regular attendance at a weight loss program.

•Patient’s belief that body weight can be controlled.

•Behavioral interventions (may be helpful).

Protective factors against weight regain: expending about 2500kcal/week, either through:

•Moderate activity for approximately 80min/day (brisk walking).

•Vigorous activity for 35min/day (jogging).

Treatment and support options:

Risks of weight loss 

Some studies have concluded that intentional weight loss reduces mortality, whereas unintentional weight loss was associated with an increased risk of mortality.

Due to an increased flux of cholesterol through the biliary system, weight loss may increase the chances of cholelithiasis developing. Diets with moderate amounts of fat that trigger gallbladder contraction may reduce this risk. Slow weight loss – e.g., 0.5–1.0kg/week – has been shown to prevent the formation of gallstones seen in patients with higher weight loss rates. Weight loss with adjustable gastric bands is associated with an incidence of gallstone formation that is no different from that in the normal population.

Stakeholders and management options 

Which of the obesity treatment or prevention approaches (Table 11) is resource-dependent? All stakeholders need to take action at global, regional, and local levels. Excess weight and obesity, as well as the related chronic diseases, are largely preventable.

Table 11. Decision scheme for weight loss treatment.

Source: Adapted from guidelines from the U.S. National Heart, Lung, and Blood Institute.

				Obesity level
				Grade 1	Grade 2	Grade 3
	Western countries
	BMI	25.0–26.9	27.0–29.9	30.0–34.9	35.0–39.9	⩾40
	Waist (cm)
	Male	94–102	94–102	⩾102	⩾102
	Female	80–88	80–88	⩾88	⩾88
	Eastern/Asian countriesa
	BMI	23.0–24.9	25.0–29.9	30.0–34.9	⩾35	⩾35
	Waist (cm)
	Male	<90	<90	⩾90	⩾90
	Female	<80	<80	⩾80	⩾80
	Treatment options
	No comorbidity	Diet	Diet	Diet	Pharmaco-therapyb	Surgeryc if supervised diets with or without pharmaco-therapyb fail
		Exercise	Exercise	Exercise	Supervised diets
				Behavioral therapy	If these fail: surgeryc
				Pharmaco-therapyb,d
	Comorbidity present	Diet	Diet	Diet	Pharmaco-therapyb	Surgeryc if supervised diets with or without pharmaco-therapyb fail
		Exercise	Exercise	Exercise	Supervised diets
		Behavioral therapy	Behavioral therapy	Behavioral therapy	Surgeryc,e
				Pharmaco-therapyb,e

BMI, body mass index; F, female; M, male.

a Asians are at greater risk, and decisions are taken one step earlier in these patients. b Only in patients with obesity-related disease who are unable to achieve adequate weight loss with available conventional lifestyle modifications and have no absolute contraindications for drug therapy. c Only in patients with obesity-related disease who are unable to lose weight with available conventional therapy and have no absolute contraindications for surgery. d While there is no evidence for surgery in patients with BMI 30–35 and no complications,exceptions are possible when there is significantcomorbidity. e There isevidence for surgery in patients with BMI 35–40 and comorbidities; according to experts, the cut-off point is likely tobe lowered to 30 during the next few years.

Individual level. The patient should avoid energy-dense foods, limit the intake of alcohol, remember the nonsatiating effects of foods rich in calories such as fat and alcohol (alcohol having an additional disinhibitory effect on eating), and bear in mind the better satiation and satiety effects of proteins followed by complex carbohydrates.

Governments, international partners, civil society and nongovernmental organizations, and the private sector should:

The food industry should:

Management options relative to available resources (Table 12, Table 13, Table 14)

Table 12. Management cascade relative to available resources.

	Resources	Management options by BMI
		25–30	30–35	35–40	>40
	High/affluent	DEB	DEB + M	DEB	DEB
				M + SD	SD + surgery
			±Surgery	±Surgery	±Surgery
	Medium/normal	DEB	DEB	DEB	DEB
				SD	SD±surgery
	Low/absent	DEB	DEB	DEB	DEB±surgery

DEB, diet, exercise, and behavior change (must be supervised); M, medication – only effective in case of moderate increase in BMI (must be supervised); SD, strictly supervised diets. Notes: 1.Whatever treatment is given, diet, exercise, and behavioral changes should always be prescribed. 2.“±Surgery” is added to indicate that if the other strategies fail, then this is an option. Even in low-resourced countries, surgery is an option if obesity needs to be addressed. An open gastric bypass is not an expensive operation. 3.In the United States, there are cheap medications (phentermine, diethylpropion) and more expensive (sibutramine) ones, with orlistat being the most expensive.

Table 13. Diet: cascade relative to the resources available.

	Resources	Diet types
		There should always be an energy restriction of at least 600kcal below everyday needs, which is in practice even more restricted than the 600kcal (since to maintain 1kg in body weight, 20–25kcal is needed, so that someone weighing 120kg needs to eat at least 2400kcal in order not to slim)
	High/affluent	High-protein diets
		Low-carbohydrate diets
	Medium/normal	High-fiber diets
		Low glycemic index diets
	Low/absent	No energy-dense foods
		Reduced-fat diets

N.B.: The costs of the diet differ in countries in which fruits and vegetables are plentiful but meat is more expensive, and the reverse may be true elsewhere. It is of course difficult to emphasize energy restriction or reduction first, before discussing in detail the changes in macronutrients and diet composition.

Table 14. Surgery: cascade relative to the resources available.

	Resources available	Surgical procedure
	High	Biliopancreatic diversion with duodenal switch
	Normal	Laparoscopic gastric bypass
		Adjustable gastric band
		Sleeve gastrectomy
	Low	Open gastric bypass; in severe obesity, a long-limb gastric bypass
		Vertical banded gastroplasty
		Sleeve gastrectomy