**6. Predictors of weight loss**

Predictors of weight loss outcomes after bariatric surgery fall can be categorized as: 1) presurgical factors, 2) postsurgical psychosocial variables (e.g., support group attendance), 3) postsurgical eating patterns, 4) postsurgical physical activity, and 5) follow-up at postsurgical clinic. There is varying evidence regarding these predictors and how well they correlate with success after bariatric surgery. However, the only factor which has been subjected to meta-analysis, and which shows a positive association with postoperative weight loss is preoperative weight loss. Other preoperatively identifiable factors associated with improved outcomes include Caucasian ethnicity or female gender [21], higher educational status, non-shiftwork working patterns, and divorced or single marital status [22].

Increased levels of preoperative physical activity and an absence of binge eating behavior also been linked with favorable results. Interestingly, increased age, smoking, a history of sexual abuse, or psychiatric illness have not been shown to have a significant impact. Conversely, diabetes mellitus seems to have a slight negative correlation with postoperative weight loss [22].

Other specific behavioral predictors associated with successful outcomes (e.g., ≥ 50% excess weight loss) are postoperative dietary adherence and support group attendance. Successful weight loss has been reported highest (92.6%) among patients reporting dietary adherence of >3 on a 9-point scale who graze no more than once-per-day. Post-operative patients with dietary adherence <3 but who graze daily or less have more than double the success rate of achieving >50% excess weight loss when their highest lifetime BMI is <53. Success rates also double for participants with low to moderate dietary adherence (3 or less) that attend support groups (either in-person or online) [23, 24]. While is unclear which specific components of these support groups are beneficial, or what constitutes optimal attendance frequency, it is possible that patients with low to moderate dietary adherence particularly benefit from the social support, accountability, and sharing of informational "tips" that promote adherence (i.e., cooking tips) [23, 24].

Alternatively, predictors of significant postoperative weight regain after bariatric surgery include indicators of baseline increased food urges, decreased well-being, and concerns over addictive behaviors. Postoperative self-monitoring behaviors are strongly associated with decreased weight regain. Data suggests that weight regain can be anticipated, in part, during the preoperative evaluation and potentially reduced with self-monitoring strategies after bariatric surgery [25]. Frequent selfweighing, at the very least, seems to be a good predictor of moderate weight loss, less weight regains, and avoidance of initial weight gain after surgery [26].

Given the chronic nature of obesity, patients after bariatric surgery should arguably be seeing a weight loss specialist for the remainder of their life. Especially after receiving a hypo absorptive operation, those patients should follow up with someone who is familiar with the specificities of their operation as well as pertinent side effects, nutritional deficiencies, etc. Long-term follow-up for patients after bariatric surgery is notoriously hard to achieve. There are multiple explanations of this, some of which are issues with the process, and others with the nature of the disease of chronic obesity. Weight loss programs sometimes do not set expectations for long term follow up in the beginning when patients start or reinforce this later. Resources can be present to get patients screened and set up for surgery but can be lacking post-operatively to keep patients engaged long-term. At some point, patients are often expected to continue follow up with their primary care physicians, who may or may

*Long Term Success and Follow-Up after Bariatric Surgery DOI: http://dx.doi.org/10.5772/intechopen.107177*

not be familiar with the nuances of the type of bariatric procedure that the patient received or have the resources themselves to assist patients in staying on track or helping struggling patients with weight regain. Individual motivation can falter when it comes to follow up, or long-term adherence to nutritional and lifestyle changes that are important for maintaining weight loss.

Very few bariatric surgery studies report long-term results with sufficient patient follow-up to minimize biased results [27]. One study of a national bariatric surgery database in France showed that the percentage of patients with one or more visits to a surgeon dropped from 87.1% to 29.6% between year 1 and 6 after surgery. Predictors of poor 5-year follow-up include male sex, younger age, absence of type 2 diabetes and poor 1-year follow-up [28].

### **7. Other reasons for long-term follow-up**

Many important long-term outcomes of bariatric surgery are still poorly understood, such as neurological and psychological complications, bone health, etc. Poor nutritional habits of obese people can result in baseline deficiency of several vitamins, minerals, and trace elements essential for body metabolism and normal physiological processes. Current bariatric surgical procedures such as sleeve gastrectomy, adjustable gastric banding, Roux-en-Y gastric bypass, and biliopancreatic diversion/duodenal switch can cause or exacerbate nutritional deficiencies and malnutrition, with different health implications unique to each surgery.

Purely restrictive operations such as adjustable gastric banding and sleeve gastrectomy affect the absorption of iron, selenium, and vitamin B12, while hypo absorptive operations such as gastric bypass and biliopancreatic diversion/duodenal switch have a more profound impact on the absorption of essential vitamins such as fat-soluble vitamins, minerals, and trace elements. Nutritional deficiencies in vitamins, minerals, and trace elements after bariatric surgery can result in clinical manifestations and diseases, such as anemia, ataxia, hair loss, and Wernicke encephalopathy [29].

Preoperative nutritional assessment and correction of vitamin and micronutrient deficiencies, as well as long-term postoperative nutritional follow-up, are important. Patient awareness, education and counseling start preoperatively, and continues after surgery. Dietetic counseling should continue frequently during the first year and be extended optionally afterwards, depending on individual and surgery specific factors. Vitamin supplementation should be discussed before surgery, with emphasis on specific needs required after surgery, and followed up on. Routine, relevant bloodwork should be obtained at appropriate intervals, with decrease in frequency as needed, but checks at least annually long term. Deviations from anticipated clinical course should prompt immediate reevaluation of nutritional levels. Planned and structured physical exercise should be systematically promoted to build and maintain muscle mass and improve bone health [30].

Weight loss programs utilizing bariatric surgery must implement robust, consistent, and evidence-based strategies to improve weight loss reduce weight regain. Long term follow up is an important factor in reinforcing behavioral modification necessary for long term weight loss, and monitoring for side effects possible after bariatric surgery. As adherence to long-term follow-up has been shown to decrease over time, it is important to identify measures that improve follow-up rates to get the maximum benefit from bariatric surgery, while minimizing long-term adverse effects and complications [31].
