About, 34% of adults and 17% of children in the United States are obese, defined as a BMI of 30 or greater. These are respectively double and triple the rates of a quarter century ago, and these numbers continue to rise. The highest rates arc in black women.
In adults, obesity is defined by body mass divided by the square of the height (BMI). Categories of obesity and overweight based on BMI proposed by the World Health Organization and National Institutes of Health (NIH) are well defined along with the most recent prevalence estimates for U.S. men and women.
Obese and overweight persons are at increased risk for heart disease, hypertension, dyslipidemia, type 2 diabetes, stroke, osteoarthritis, sleep apnea, gallbladder disease, certain cancers (endometrial, breast, colon), and overall mortality. The risks increase progressively with rising BMI. Obesity also is associated with reduced quality of life, societal discrimination, and increased health care costs. It is estimated that obesity added $147 billion to health care costs in 2008. In persons aged 65 years and older, obesity is associated with impaired physical functioning, including difficulty with activities of daily living.
Screening and Evaluation
The NIH and the U.S. Preventive Services Task Force (USPSTF) recommend screening all adults for obesity. The USPSTF recommends screening by calculating the BMI. The NIH recommends screening both with BMI and waist circumference measurement. Waist circumference is measured with a measuring tape placed around the waist at the level of the iliac crest. Central obesity (waist circumference in men >102 cm [40 in]; in women >88 cm [35 in]) is associated with an increased risk for type 2 diabetes, dyslipidemia, hypertension, and heart disease, not only in obese persons, but also in those who are overweight.
The assessment of obese patient begins with history and physical examination. The history should elicit chronology of weight gain, family history of obesity, medications which can promote weight gain, exercise, eating patterns, and symptoms and risk factors.
Assessment for comorbidities associated with obesity should be considered. The USPSTF does not recommend specific laboratory tests based on the presence of obesity, but the American Diabetes Association (ADA) recommends screening for diabetes in patients with a BMI of 25 or greater who have other risk factors for diabetes. Although the major cause of obesity is imbalance between caloric intake and energy expenditure, clinicians should consider less common causes as well.
The physician should assess the patient’s motivation for weight loss, and an individualized treatment plan should follow. Success may be improved by a team of health professionals, including a dietitian, a behavioral therapist, and an exercise therapist. The decrease caloric input and increase energy expenditure will result in weight loss.
The goal is to reduce body weight of 10% at a rate of 0.5 to 1 kg (1-2 lb.) per week during a 6-month period. This degree of weight loss will reduce the risk of many complications of obesity. In addition to lifestyle modification (behavioral changes, exercise, and diet), medication and surgery have become increasingly popular options. The overall management
The USPSTF recommends that clinicians offer all obese patients intensive counseling and behavioral interventions. This includes counseling in diet and exercise. Lifestyle modification has been shown to be the most effective intervention to prevent type 2 diabetes, and die ADA recommends lifestyle modification for diabetes prevention.
Behavioral therapy focuses on patient’s attention on his or her personal eating patterns and assists the patient to control or modify food intake, increase exercise, and avoid stimuli that trigger eating. Behavioral therapy is best when accomplished by a therapist trained in this technique.
Exercise as monotherapy is likely not adequate for significant weight loss. In a 12-month study of moderate to vigorous exercise for 1 hour daily, 6 days per week, women lost only 1.4 kg (3.1 lb.) and men lost 1.8 kg (4 lb.). However, exercise at a level of walking 60 to 90 minutes per day is effective in maintaining weight that is lost and, therefore, is a useful adjunct to any weight loss program. Exercise has other health benefits, including improving cardiovascular health and decreasing waist circumference.
Consistent Dietary Caloric Restriction
Dietary caloric restriction leads to successful weight loss. Obese patients can lose approximately 0.45 kg (1 lb.) weekly by decreasing their intake by 500 to 1000 kcal/d below what is needed to maintain current weight. Total calories should not be restricted to less than 800 kcal/d as “very-low-calorie” diets arc no more effective than low-calorie diets for successful long-term weight loss and have higher adverse consequences. No one diet has been shown to be superior to others when long-term outcomes are measured.
• All obese patients should be offered intensive counseling and behavioral interventions to encourage weight loss, including counseling in diet and exercise.
• No one diet has been demonstrated superior to others in achieving long-term weight loss.
With the rising prevalence of obesity, drug therapy has emerged as an attractive option for weight loss in obese patients, especially when lifestyle modification is ineffective. Short-term and long-term safety may limit their use in many patients. Current FDA-approved options for drug therapy in the United States include sympathomimetic drugs that suppress appetite (phentermine, diethylpropion) and drugs that alter fat absorption (orlistat). Several appetite suppressant medications, including sibutramine, have been removed from the market for safety concerns.
Sympathomimetic drugs are approved only for short-term use as an adjunct to other weight loss programs. Significant increases in blood pressure and arrhythmias can occur with phentermine; caution is indicated in patients with hypertension and cardiovascular disease, a recent study of low-dose, controlled- release phentermine plus topiramate combined with office based lifestyle intervention, modest weight loss was achieved (8.1 kg [17.8 lb.] at 56 weeks compared with 1.4 kg [3.1 lb.] in the placebo group. Significant improvement was noted in waist circumference, blood pressure, and lipid levels in the treatment group. Combination phentermine/topiramate has been FDA-approved for the treatment of obesity.
Orlistat is now available over the counter, is a lipase inhibitor that leads to fat malabsorption. A recent study showed the mean weight loss in patients treated with orlistat was 2.9 kg (6.4 lb.) at 12 months. Secondary benefits included reductions in LDL cholesterol level and blood pressure and, in patients with diabetes, glycemic control was improved. Approximately 15% to 30% of patients experienced gastrointestinal side effects (flatus, abdominal cramps, fecal incontinence, oily spotting), especially while consuming high-fat diets. Orlistat has not been associated with serious cardiovascular side effects. However, a recently completed review by the FDA noted rare reports of severe liver injury with orlistat. Malabsorption of fat-soluble vitamins A, D, and E has been reported, and vitamin supple mentation is advisable while taking the medication.
Pharmacologic options for weight loss include orlistat for long-term use, the appetite suppressants phentermine and diethylpropion for short-term use, and loriciferan.
For class II or III obese patients (BMI >35) in whom diet, exercise, and/or medication have failed, especially those with significant obesity-related comorbidities, weight loss surgery should be considered. The NIH Consensus Development Conference Statement suggested the following criteria for considering a patient for bariatric surgery:
1. Patients should be well-informed, motivated, eager to participate in treatment and long-term follow-up, and have acceptable operative risks.
2. Patients should have a BMI that exceeds 40.
3. Patients with a BMI between 35 and 40 with obesity- related comorbidities, such as severe sleep apnea, diabetes, or severe joint disease, should be considered.
4. Patients should be evaluated by a multidisciplinary team with medical, surgical, psychiatric, and nutritional expertise.
Surgical therapies involve restriction of stomach size and malabsorption of ingested calories as their mechanisms of action. Based on worldwide survey data, the most common procedures are Roux-en-Y gastric bypass (65.1%), laparoscopic adjustable band procedures (24%), vertical banded gastroplasties (5.4%), and biliopancreatic diversion (4.8%) (Figure 17). The laparoscopic adjustable band procedure is increasing in popularity among patients and physicians, although the weight loss with loss with this procedure, and restrictive surgeries in general, is less robust.
Randomized controlled and cohort studies comparing bariatric surgery with nonsurgical interventions have found that surgery results in more dramatic and sustained weight loss and leads to improvement in obesity-related comorbidities. In a meta-analysis comprising 16,944 patients with a mean BMI of 47 (range 32-69) who underwent some type of bariatric procedure, the average weight loss at 12 months was 43.46 kg (95.6 lb.) for Roux-en-Y gastric bypass, 32.16 kg (70.8 lb.) for vertical band gastroplasty’, 30.19 kg (66.4 lb.) for adjustable gastric banding, and 51.93 kg (114.2 lb.) for biliopancreatic diversion. Diabetes resolved in 76.8% of patients, hypertension resolved in 61.7%, obstructive sleep apnea resolved in 85.7%, and hyperlipidemia improved in 70%. Another meta-analysis reached similar conclusions. In a large retrospective cohort study, all-cause mortality decreased by 40% in the surgery group compared with the control group at a mean follow-up of 7.1 years. However, in a recent subset of obese, high-risk, primarily male patients, bariatric surgery was not significantly associated with survival during a mean of6.7 years of follow-up. Some studies document short-term improvements in quality of life.
Bariatric surgery carries procedure-specific short-term and long-term risks. Surgical mortality rates are low (<1%) and appear to be reduced with the laparoscopic approach and with surgeons who perform a high volume of the procedures.
An average of 20% to 25% of lost weight is regained in 10 years. Dietary counseling, and behavioral modification are recommended. For patients who have undergone a Roux-en-Y procedure, recent guidelines suggest twice yearly monitoring of vitamin D, calcium, phosphorus, parathyroid hormone, and alkaline phosphatase levels. To assess nutritional deficiencies after a malabsorptive procedure, ferritin, vitamin B, folate, vitamin D, and calcium levels should be assessed every six months for the first 2 years and then annually. Bone mineral density testing is recommended yearly until stable.
The prevalence of obesity was 42.4% in 2017~2018. [Read CDC National Center for Health Statistics (NCHS) data brief]
From 1999–2000 through 2017–2018, the prevalence of obesity increased from 30.5% to 42.4%, and the prevalence of severe obesity increased from 4.7% to 9.2%. [Read CDC NCHS data brief]
Obesity-related conditions include heart disease, stroke, type 2 diabetes, and certain types of cancer that are some of the leading causes of preventable, premature death.
The estimated annual medical cost of obesity in the United States was $147 billion in 2008 US dollars; the medical cost for people who have obesity was $1,429 higher than those of normal weight.
Obesity affects some groups more than others.
Non-Hispanic Black adults (49.6%) had the highest age-adjusted prevalence of obesity, followed by Hispanic adults (44.8%), non-Hispanic White adults (42.2%) and non-Hispanic Asian adults (17.4%).
The prevalence of obesity was 40.0% among adults aged 20 to 39 years, 44.8% among adults aged 40 to 59 years, and 42.8% among adults aged 60 and older.
Obesity and socioeconomic status
The association between obesity and income or educational level is complex and differs by sex and race/ethnicity.
Overall, men and women with college degrees had lower obesity prevalence compared with those with less education.
By race/ethnicity, the same obesity and education pattern was seen among non-Hispanic White, non-Hispanic Black, and Hispanic women, and among non-Hispanic White men, although the differences were not all statistically significant. Although the difference was not statistically significant among non-Hispanic Black men, obesity prevalence increased with educational attainment. Among non-Hispanic Asian women and men and Hispanic men, there were no differences in obesity prevalence by education level.
Among men, obesity prevalence was lower in the lowest and highest income groups compared with the middle-income group. This pattern was seen among non-Hispanic White and Hispanic men. Obesity prevalence was higher in the highest income group than in the lowest income group among non-Hispanic Black men.
Among women, obesity prevalence was lower in the highest income group than in the middle-and lowest-income groups. This pattern was observed among non-Hispanic White, non-Hispanic Asian, and Hispanic women. Among non-Hispanic Black women, there was no difference in obesity prevalence by income.