Achieving optimal weight outcomes for patients with obesity is important to the management of their chronic disease. All interventions present risks for weight regain. Bariatric surgery is the most efficacious treatment, producing greater weight losses that are sustained over more time compared to lifestyle interventions. However, approximately 20–30% of patients do not achieve successful weight outcomes, and patients may experience a regain of 20–25% of their lost weight. This paper reviews several factors that influence weight regain after bariatric surgery, including type of surgery, food tolerance, energy requirements, drivers to eat, errors in estimating intake, adherence, food and beverage choices, and patient knowledge. A comprehensive multidisciplinary approach can provide the best care for patients with weight regain. Nutrition care by a registered dietitian is recommended for all bariatric surgery patients. Nutrition diagnoses and interventions are discussed. Regular monitoring of weight status and early intervention may help prevent significant weight regain.
1.3. Energy Requirements. Nutrition prescription is an important component of nutrition intervention of weight management. It can be quite challenging to determine energy (calorie) requirements. Predictive equations are commonly used; however, the accuracy can vary and do not account for body composition which can impact energy requirements [20, 21]. There are reductions in energy requirements during and shortly after weight loss . With the significant changes
of both fat mass and fat free mass after bariatric surgery, it puts into question how much reduction in energy requirements occur with weight loss.
Adaptive thermogenesis is a decrease in energy expenditure (EE) after weight loss beyond what can be predicted from changes in fat mass and fat free mass . In a study with nonsurgical, obese subjects, those with larger weight loss showed a greater reduction in measured resting metabolic rate (RMR) compared to predicted values . Several studies have assessed metabolic rate in bariatric surgery patients,and they have found a decrease in RMR after surgery .
In patients with vertical banded gastroplasty, a reduction in sleeping metabolic rate persisted after adjustment for body composition, at both 12 months and 98 months as long as weight loss was maintained . In RYGB patients who experience weight regain, it has been seen that their RMR is lower than the weight stable group and that predictive formulas overestimate their RMR . Reduction in energy requirement is sustained as long as weight loss is maintained in both surgical and nonsurgical patients; for those who regain weight to or above their starting weight, adaptive thermogenesis is no longer observed [4, 24].
An important component of total daily energy requirements is energy expenditure. Physical activity is important for both weight and other health related outcomes; however, most Canadians do not meet the recommended levels of activity, regardless of BMI. In one particular study, only 1/3 of the surgical group reported engaging in a level of physical activity consistent with recommendations for prevention of weight regain, compared with 60% of the non-surgical group
. Regular activity after surgery is related to better % EWL, maintenance of loss and fat-free mass [25, 26]. The increase in total amount of activity from presurgery to postsurgery has been found to be more important than the intensity. Overall, more physical activity is associated with better postoperative weight loss maintenance [27, 28].
A sustained adaptive thermogenesis favors positive energy balance and may predispose to weight regain . Measurement of resting energy requirements would improve accuracy of nutrition prescriptions, and optimization of energy expenditure may be helpful to achieve energy balance to help prevent further weight regain.
Stoklossa CJ. Gastroenterology Research and Practice, Volume 2013.