Nutritional Implications of Obesity: Before and After Bariatric Surgery.

Abstract

Obesity is defined as the accumulation of excess body fat to the extent that it may have an adverse effect on health. Generally, the body mass index (BMI) is utilized to characterize further the degree of obesity, and it is calculated based on height and weight in kg/m2. According to the definition established by the World Health Organization, individuals are classed as overweight if their BMI is ≥25, whereas obese individuals are those with a BMI ≥30. Based on the degree, obesity is further categorized into class I (BMI 30–34.9), class II (BMI 35–39.9), and class III (BMI ≥40). There is a linear correlation between incidence of chronic diseases and increased BMI. Obesity is now recognized as a worldwide epidemic, and its incidence is increasing exponentially. According to the World Health Organization's projections from 2005, approximately 1.7 billion people are considered overweight, and at least 400 million adults are obese.1 In the United States alone, nearly 33% of the population (97 million) are obese, and approximately 10 million people are morbidly obese (class III).1,2 Although obesity has a multifactorial etiology, the most relevant causes can be grouped into environmental, genetics, and behavioral factors. In general, increased calorie consumption and decreased physical activity play a key role. Contrary to common beliefs, the obese individual is not well nourished. The routine screening of obese patients prior to bariatric surgery has highlighted the multiple nutritional deficiencies of this patient population. The causes of this phenomenon are not entirely understood. It seems likely, though, that the excess caloric intake does not mean the overconsumption of fresh fruit, vegetables, and unprocessed foods, but rather the lack of consumption of these types of foods, exposing obese individuals to several micronutrient deficiencies.3 Therapeutic options for weight loss include dietary and behavioral modifications, increased physical activity, pharmacologic therapy, and, lastly, surgical intervention. Commonly, caloric restriction with behavioral modifications and physical activity lead to an average weight loss of only 5–10%.4 The addition of pharmacologic intervention can improve the results to 15%. Unfortunately, none of these interventions leads to long-lasting results, and weight regain seems to be the norm.5 Surgery, on the other hand, has been proven to provide consistent and durable weight loss, as stated by the National Institute of Health Consensus Development Conference Panel.6 In addition, weight loss surgery is associated with resolution or improvement, to different degrees, of the comorbid conditions associated with obesity.7 Although highly effective in terms of weight loss and resolution of comorbidities, the different bariatric surgery procedures can contribute to nutritional derangements postoperatively. Certainly, the procedures that affect the physiologic absorption of nutrients have a higher tendency to determine deficiencies, but also the procedures that solely reduce the quantity of intake can affect individuals' long-term nutritional status. It is a prime responsibility of the bariatric surgery team to assess, educate, and follow the obese patient in order to avoid dangerous nutritional abnormalities.