Prevalence and Epidemiology of Gastrointestinal Symptoms Among Normal Weight, Overweight, Obese and Extremely Obese Individuals

Until recently, the epidemiology of gastrointestinal (GI) symptoms had not been adequately studied in relation to increasing body mass index. To date there are only a few studies in the literature, and thus the relationship between obesity and specific GI symptoms is poorly understood. Future studies that incorporate different ethnicities from varied geographic locations are urgently required. A greater understanding of how GI symptoms are related to obesity and the physiology will be important in the clinical management of these patients.

The obesity epidemic has brought with it a barrage of comorbid conditions, medical and psychological complications, and complex patients for the physician to interpret. Studies on the role of gastrointestinal (GI) symptoms in overweight and obese individuals have been very limited, which is surprising given that the GI tract is responsible for the mechanical and chemical breakdown of food for absorption by the body. The prevalence of those classified as overweight in the United States has not changed much since the 1960s, however, there has been a significant almost threefold increase in the prevalence of obesity that started in 1976 to 1980 and peaked in 1999 to 2000. The largest increase has occurred in the extremely obese category; there has been a sevenfold increase in prevalence in this category between 1960 and 2006 ( Fig. 1 ). In the middle of this epidemic of increasing body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters) in the United States, the first study assessing the epidemiology of digestive symptoms was conducted at the Johns Hopkins Weight Management Center in 1994. The study aimed to determine the prevalence of GI symptoms among obese and normal weight binge eaters.

It was almost a decade later when a patient-based study of morbidly obese patients undergoing laproscopic Roux-en Y gastric bypass reported substantial increases in GI symptoms compared with normal controls. Following this initial report, there were 3 population-based studies from the United States, New Zealand, and Australia that provided new information about the prevalence of GI symptoms among various BMI categories (normal 18.5–24.9 kg/m ² , overweight 25.0–29.9 kg/m ² , obese class I 30.0–34.9 kg/m ² , obese class II 35.0–39.9 kg/m ² , and obese class III >40.0 kg/m ² ). Subsequently, there have been an 5 more studies including 2 from Europe, 2 from the United States, and a recent study from Iran. Moreover, there have been other studies that have provided limited information because of the groups assessed or the variables selected in these studies. Despite the global prevalence of obesity, it is evident from the literature that there are few studies assessing the epidemiology of GI symptoms among overweight, obese, or extremely obese individuals either in the community or among patients in the clinical setting.

This review focus only on studies that have aimed to determine the prevalence of multiple GI symptoms in either patient-based samples or in the community ( Table 1 ).

Table 1

Characteristics of studies assessing GI symptoms among overweight and obese individuals

Study	Year	Country	Total (n)	Weight Classification	Study Design	Study Sample	GI Symptoms
Foster et al	2003	United States	43	BMI	Cross-sectional	Patient	Abdominal pain, GERD, IBS, reflux, dysphagia
Delgado-Aros et al	2004	United States	1963	BMI	Cross-sectional	Population	Nausea, vomiting, satiety, upper abdominal pain, lower abdominal pain, bloating, diarrhea, constipation
Talley et al	2004	New Zealand	980	BMI	Cohort	Population	Abdominal pain, bloating, heartburn, acid regurgitation, diarrhea, constipation, IBS
Talley et al	2004	Australia	777	Increased BMI	Cross-sectional	Population	Nausea, vomiting, early satiety, upper abdominal pain, lower abdominal pain, bloating, postprandial fullness, hard stools, decreased stools, increased stools, loose watery stools, heartburn, acid regurgitation
Aro et al	2005	Sweden	983	BMI	Cross-sectional	Population	Dysphagia, fullness, retching, acid regurgitation, early satiety, nausea, vomiting, heartburn, central chest pain, burning feeling rising in chest, constipation, diarrhea, incomplete evacuation, pain at defecation, pain relieved at defecation, straining, urgency, flatus, abdominal distention, nightly urge to defecate
van Oijen et al	2006	Netherlands	1023	BMI	Cross-sectional	Patient	Acid regurgitation, heartburn, dyspepsia, GERD, lower abdominal pain
Cremonini et al	2006	United States	637	Weight loss/gain	Cohort	Population	Dyspepsia, GERD, chest pain, dyspepsia dysmotility, dyspepsia pain
Cremonini et al	2009	United States	4096	BMI	Cross-sectional	Population	Abdominal pain, fullness, food staying in stomach, bloating, acid regurgitation, heartburn, nausea, vomiting, dysphagia, anal blockage, diarrhea, constipation, lumpy/hard stools, loose/watery stools, fecal urgency, fecal incontinence
Pourhoseingholi et al	2009	Iran	2790	BMI	Cross-sectional	Population	Abdominal pain, constipation, diarrhea, bloating, heartburn, anal pain, anal bleeding, nausea and vomiting, dysphagia, incontinence

Gastrointestinal symptoms

The studies published so far have assessed 47 GI symptoms ( Box 1 ). These consist of upper and lower GI symptoms. The most common symptom assessed in these studies was abdominal pain with 7 out of 9 studies reporting an overall abdominal pain; only 2 studies reported upper and lower abdominal pain as separate symptoms. Upper GI symptoms included acid regurgitation, gastroesophageal reflux disease (GERD), dysphagia, vomiting, heartburn, dyspepsia, retching, and nausea; lower GI symptoms included constipation, diarrhea, fecal incontinence, incomplete evacuation, and anal blockage. Some symptoms were commonly reported in 4 or more studies and these included acid regurgitation, bloating, constipation, diarrhea, dysphagia, heartburn, nausea, and vomiting. Although irritable bowel syndrome (IBS) is a syndrome and not a categoric symptom, this was included because the data were available from the studies.

Box 1

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