Weight Regain After Bariatric Surgery

Fig. 10.1

Percent weight change trajectories for Roux-en-Y gastric bypass and laparoscopic adjustable gastric band (from Courcoulas AP, Christian NJ, et al. Weight change and health outcomes at 3 years after bariatric surgery among individuals with severe obesity. JAMA. 2013;310(22), with permission)

Fig. 10.2

Gastric bypass surgery weight regain between the second and sixth years postoperatively (from Adams TD, Davidson LE, Litwin SE, Kolotkin RI, LaMonte MJ, Pendleton RC, et al. Health benefits of gastric bypass surgery after 6 years. JAMA. 2012;308(11):1122–31, with permission)

10.2 Understanding the Mechanism of Action of Metabolic Procedures

Understanding how to maximize weight loss and obesity-related disease remission and understanding weight regain requires a broad understanding of how the procedures work. In the early history of bariatric procedures surgeons primarily constructed alterations in the stomach that were designed to restrict the amount of food people could eat (stapling of the stomach) or created malabsorption (bypassing a portion of the bowel). At the time, our understanding of the primary mechanism of surgery was limited to these two theories. The observation of remission of obesity-related disease, in particular diabetes, spurred the development of animal models to study how it was occurring.

We learned that procedures that cause restriction, like the adjustable gastric band, result in changes in intestinal hormones that are very similar to what would happen to a patient on a voluntary diet. For example, the hormone that causes hunger, ghrelin, increases after the adjustable gastric band is inserted, thereby making the patient hungry. The hormone that triggers satiety, GLP1, decreases. Devices that are based on restriction are similar to a voluntary diet and over time many patients are unable to maintain the initial weight loss. In a large and well-conducted trial, the 3-year weight loss after adjustable gastric band was only 19 % on average [1]. Metabolic procedure s, like the sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), operate primarily through different mechanisms. Currently, it appears that sleeve or gastric bypass restriction of food and malabsorption of calories account for only 5–7 % of the weight loss effect.

The changes that occur after a metabolic bariatric procedure are the following(3):

1.

A change occurs in the hormone signaling from the gut to the brain.
2.

Changes in the microbiome occur due to the different ways in which food is processed: these changes favor bacteria that are not as efficient at wringing calories out of food.
3.

Changes occur in the thermodynamics of the patient which causes an increase in energy expenditure in part through hormonal signaling and activation of receptors that cause an increase in thermogenesis.
4.

Changes occur in the food-reward part of the brain which cause postsurgical patients to crave different and healthier foods that are lower in fat and sugar.
5.

Leptin levels decline as the fat percentage decreases, resulting in less leptin resistance.
6.

The level of inflammation decreases as fat cells shrink in size, there by affecting the level of inflammation of the blood vessels that, in turn, affect every body system.

10.3 Why Weight Gain Occurs After a Bariatric Procedure

Once the patient experiences the Genetic Reset™ afforded by a metabolic bariatric surgery procedure, the patient then has an opportunity to make a permanent change in his/her weight and improve his/her health. Nationally accredited bariatric surgery programs have specific preoperative and postoperative education and support programs designed to allow the patient to maximize their Genetic Reset™ and health. Some patients may have such an overwhelming burden of genetic predisposition to obesity that any given procedure may not force enough change on the system. These patients may gain weight after the procedure regardless of the environmental changes they make. However, it seems likely that the failure of a patient to maximize his/her environmental change opportunities will make weight loss less robust or long lived. Interviews with patients who have regained a substantial amount of weight often show a long-standing history of familial obesity and an inability or failure to make substantial changes in their culture around food and exercise .

10.4 Ongoing Monitoring of Bariatric Surgical Patients

10.4.1 Measurement and Communication of Weight Status

All patients undergoing bariatric surgery procedures should be subsequently coded in the electronic health record as having a history of bariatric surgery (ICD10 Z98.84). Every patient seen in the practice for any reason should have a measured height, weight, and waist circumference taken with calculation of BMI and body fat percentage. Taking these measurements as a standard part of every physical exam for all patients will minimize any feeling of being singled out. These important vital signs of health should be given in writing to the patient. The patient will have a nadir of weight loss after bariatric surgery ranging in time from 6 months to 2 years after the procedure. After that, some weight regain may occur and it is crucial that the patient knows to immediately seek care and not delay until they have gained a substantial amount—defined as more than 10 %. Weight regain is accompanied by all the previous metabolic and epigenetic changes back into the patient’s system, making it harder to get that weight back off. Often patients who have been big are extremely sensitive to weight regain and want to have help and guidance if they start to regain weight.

10.4.2 Ongoing Evaluation of Obesity-Related Disease

Patients who have been obese will have a history of obesity-related disease. In the medical record, the obesity-related disease should be documented, i.e., history of type 2 diabetes and obstructive sleep apnea, so that providers are aware of these previous diagnoses. Once the patient loses weight they often go into temporary or permanent remission of obesity-related disease. The amount of weight loss and remission depends on the type of device or procedure utilized. For example, type 2 diabetes has a remission rate of 68.7 % after RYGB and 30.2 % of LAGB at 3 years [4] (Fig. 10.3). For this reason annual testing of HbA1C and fasting blood sugar is a required component of a patient’s annual lab work. Treatment of obstructive sleep apnea should not be discontinued without proof that the apnea has indeed resolved. Hypertension does not respond as well as other obesity-related diseases and often the bariatric patient will continue to need treatment even after massive weight loss and almost certainly during weight regain.

Fig. 10.3

Modeled probabilities and 95 % CIs for diabetes remission for each postoperative year of follow-up as a function of percent weight loss in participants undergoing LAGB (red lines) and RYGBP (blue lines). aRR estimates and 95 % CIs for the association between surgical type (RYGBP vs. LAGB) and diabetes remission are adjusted for percent weight change from baseline and a propensity score consisting of baseline demographic and clinical characteristics associated with the type of bariatric surgical procedure. aRR is greater for RYGBP than LAGB at each postoperative year; P ≤ 0.001 for each time point (from Purnell JQ, Selzer F, Wahed AS, Pender J, Pories W, Pomp A, et al. Type 2 diabetes remission rates after laparoscopic gastric bypass and gastric banding: results of the longitudinal assessment of bariatric surgery study. Diabetes Care. 2016;39(7):1101–7, with permission. Copyright 2016 by American Diabetes Association)

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