What Should Gastroenterologists Do about Obesity?
the esophagus in men. Obesity, the metabolic syndrome, and rapid weight loss are modifiable risk factors of gallstone formation, while an increase in BMI of 5kg/m2 is strongly associated with gallbladder cancer in women but not in men. The prevalence of non-alcoholic fatty liver disease (NAFLD), cirrhosis, and hepatocellular carcinoma has been independently associated with obesity, with the correlation between NAFLD and obesity being particularly robust. The prevalence of NAFLD ranges from 3 to 24% in the general population but increases to 58–74% in obese subjects. The metabolic syndrome, a persistent inflammatory state that promotes fatty acid accumulation as it promotes insulin resistance, is associated with obesity. NAFLD is considered the hepatic equivalent to the metabolic syndrome. As the parameters of the metabolic syndrome worsen, the risk for developing non-alcoholic steatohepatitis increases. Autopsy studies have shown an increase in the relative risk for developing cirrhosis in obese patients. A meta- analysis of overweight and obesity relative to liver cancer showed the risk for developing hepatocellular carcinoma to be considerably higher in men. If there were not already enough reasons to maintain a healthy weight, there is strong evidence that obesity, as measured by BMI, weight, waist-to-hip ratio, or waist circumference, is a significant risk factor for diverticulosis, diverticulitis, and diverticular bleeding. Obesity is a risk factor for advanced adenomatous colon polyps and colon cancer, demonstrating a dose–response relationship. For every one-unit increase in BMI above 30, there is a 1% increase in the frequency of advanced adenomas. For every two-unit increase in BMI, the risk for cancer increases by 7%, and for each 2cm increase in waist circumference the risk increases by 4%. Fecal incontinence, which is common in morbidly obese women, can worsen following bariatric surgery owing to diarrhea.
So, where do we go from here? Gastroenterologists and hepatologists, as they see so much obesity-related disease, must be diligent about counseling and treating overweight and obesity in their patients, with the ultimate objective of preventing progression to irreversible diseases such as cirrhosis and cancer. Just a 5–10% loss of bodyweight can substantially reduce symptoms of GERD, strengthening the evidence that excess weight is a major cause of GERD and that weight loss can be an effective treatment. Use of acid-suppressing agents will reduce
symptoms but not stop reflux, which appears to be a product of increased intra-abdominal pressure. A diet low in fat and rich in fruits, vegetables, and wholegrains is associated with reduced reflux symptoms and weight loss and may reduce the risk for diverticulitis, colon polyp formation, and many cancers. In NAFLD, a 10% loss of weight leads to a significant reduction in abnormal liver enzymes, which may become normal. Substantial weight loss in patients undergoing gastric bypass surgery is accompanied by a marked reduction in transaminases and a regression of fatty liver by cross- sectional imaging.
Any effective treatment plan must consider the patient’s willingness to undergo therapy, his/her ability to comply with specific treatment approaches, access to skilled care-givers, and financial considerations. Lifestyle modification, which involves a program of appropriate diet, physical activity, and behavior therapy, should be considered for all patients with a BMI ≥25kg/m2. Bariatric surgery may be necessary in patients with severe obesity and those who have significant comorbidities and fail to lose weight with non-surgical therapy.
Long-term pharmacotherapy should be considered in appropriate patients who are unable to achieve adequate weight loss after six months of lifestyle therapy and who have a BMI ≥30kg/m2, or ≥27kg/m2 with concomitant obesity-related disease. Yet, despite an expanse of knowledge of the causes and consequences of obesity in recent decades and breakthroughs in weight loss treatments, there are few and, with the recent withdrawal of sibutramine in the US, increasingly fewer long-term pharmacologic treatment options. In the US, the Food and Drug Administration has been resistant to allowing weight loss therapies to come to market as a result of safety concerns. Persons for whom weight loss treatments are not intended can be at risk for abuse. Meanwhile, the short- and long-term health risks of obesity are so significant, costly, and detrimental that failing to tackle the safety issues itself has dire consequences. The role of the gastroenterologist includes that of educator-in-chief on gastrointestinal and hepatic diseases for our patients, trainees, and colleagues, including information on the consequences of obesity. Gastroenterologists everywhere, it is time to step up to the plate. n
US GASTROENTEROLOGY & HEPATOLOGY REVIEW
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