The long-term efficacy of bariatric surgery is not entirely clear, and weight regain and diabetes relapse are problems for some patients. Exercise is a feasible and clinically effective adjunct therapy for bariatric surgery patients. We hypothesize that exercise is also a critical factor for long-term weight loss maintenance and lasting remission of type 2 diabetes.
- Bariatric surgery can be an effective therapeutic option for obesity.
- The long-term efficacy of bariatric surgery is not entirely clear; weight regain and diabetes relapse are problems for some patients.
- Recent evidence indicates that exercise is a feasible and clinically effective adjunct therapy for bariatric surgery patients.
- Exercise may also be a critical factor for long-term weight loss maintenance and lasting remission of type 2 diabetes.
Bariatric surgery is a generally safe and effective treatment option for obesity and encompasses a number of different procedures. The most commonly performed bariatric surgery procedures in the sleeve gastrectomy and Roux-en-Y gastric bypass (RYGB), result in dramatic weight loss, improvements in peripheral tissue insulin sensitivity, and diabetes remission in a large percentage of patients. A structured exercise program is a feasible and effective adjunct therapy for bariatric surgery patients that elicits additional cardiometabolic benefits compared with those experienced with bariatric surgery–induced weight loss alone. Structured exercise increases total daily energy expenditure and improves skeletal muscle mitochondrial energetics, fat oxidation, and insulin sensitivity. It is not clear, however, whether exercise or physical activity can overcome the “metabolic adaptation” or decreased energy expenditure that occurs with surgery-induced weight loss and have an impact on overall daily energy balance. In recent years, the advent of technology that permits quantitative and comprehensive assessment of nonexercise PA and sedentary behavior underscores the importance of these behaviors in energy balance, weight regulation, and the development or worsening of obesity. These behaviors also likely contribute to outcomes after bariatric surgery.
The Long-term Efficacy of Bariatric Surgery Is Variable
Why Do Some Bariatric Surgery Patients Experience Suboptimal Weight Loss, and Weight Regain?
The problem of suboptimal weight loss, weight regain, is increasingly being recognized, and further investigation is needed to understand the physiological and behavioral origins of interpatient variation in surgery-induced weight loss. Current evidence indicates that greater BMI, age, diagnosis, cognitive function, personality, and mental health are strong predictors of suboptimal weight loss and diabetes relapse.
From the perspective of energy balance, a reduced TDEE per kg of fat-free mass (FFM) could compensate for bariatric surgery–induced caloric restriction, which could underlie the variation in weight loss and predispose weight regain. This metabolic adaptation, or hypometabolism, that occurs with weight loss includes changes in resting metabolic rate (RMR), diet-induced thermogenesis (DIT), and PA-associated EE (the main components of TDEE), has not been studied after bariatric surgery.
study determined by total body mass, primarily FFM, and so the loss of adipose and particularly lean tissue mass after bariatric surgery means that less energy is required to sustain resting metabolism. Furthermore, weight loss–induced adaptive thermogenesis results in lower energy expenditure per kilogram of lean tissue than what would be expected. In other words, the body becomes more efficient at using energy. Two mechanisms may explain this adaptation in humans; first, the loss of the different components of FFM mass (internal organs and skeletal muscle mass) does not happen with the same proportion or at the same rate. In this regard, the gastrointestinal system (GI) has a high resting energy demand, up to 10% of body oxygen consumption, and so GI resection (gastric sleeve for example) is likely a mechanism for a reduction in RMR per lean tissue mass.
The alterations in RMR after bariatric surgery have been described in three phases: the first is an elevated RMR that occurs immediately after surgery; a second phase of adaptive thermogenesis is evident between the third and sixth month postsurgery; and third, the adaptive thermogenesis typically disappears after the first year postsurgery. The degree of adaptive thermogenesis has been suggested to be related to the degree of energy balance, so patients who are in energy balance have suppressed adaptive thermogenesis.
EXERCISE AS AN ADJUNCT THERAPY
Bariatric Surgery Patients Engage in Very Low Daily Physical Activities
Is Presurgery Exercise a Viable Therapeutic Approach?
A common belief exists, even in contemporary articles, that lifestyle intervention approaches including exercise are ineffective for treatment of persons with severe obesity. Part of the reason for this perception is that there have been very few well-controlled exercise trials in severely obese bariatric surgery patients.
Does Exercise Contribute to Greater Weight Loss After Bariatric Surgery?
Exercise alone typically results in weight loss of less than 3% of initial body weight. This often leads to a perceived lack of health benefit of exercise by obese patients in the absence of appreciable weight loss, despite its physiological and psychological health benefits independent of weight loss. However, exercise administered in combination with diet-induced caloric restriction results in significantly greater reductions in body weight (−8.4% vs −11.4% for men and −5.5% vs −7.5% for women after 4-month workout period), even in patients with severe obesity (10.9 kg vs 8.2 kg over a 6-month intervention. Currently, there is scant equivalent evidence for this effect of exercise with bariatric surgery patients.
The lack of an exercise effect on weight in these intervention studies is likely due to the strong influence of surgery as well as the large variability in weight loss. Reports on the mean weight loss induced by surgery with or without exercise do not account for the possibility that a higher dose or intensity of exercise may elicit additional weight loss or alter body composition or regional adiposity in a favorable way after surgery. Aerobic exercise is particularly effective at reducing visceral adipose tissue, a fat depot that is strongly linked to hepatic insulin resistance (IR) and T2D. It is also plausible that exercise could be particularly effective at eliciting additional weight loss in patients who are experiencing suboptimal weight loss after surgery.
Is Exercise Important for Weight Loss Maintenance?
A significant number of bariatric surgery patients also experience weight regain and reoccurrence of comorbidities. Maintaining weight loss is a well-recognized problem for patients who try diet-induced calorie restriction to lose weight (nonsurgical), with reports suggesting that 12–18 months after weight loss, 33%–50% of initial weight loss is regained. Exercise has proven to be an important factor for long-term weight loss maintenance after calorie restriction.
Exercise May Counteract the Physiological Adaptations That Occur With Bariatric Surgery–Induced Weight Loss
Exercise, particularly resistance exercise, can help to attenuate muscle mass loss in RYGB patients. In the context of diet-induced calorie restriction, a number of randomized studies have shown that during weight loss, supervised exercise prevents the loss of FFM. However, the long-term significance of exercise-induced preservation of muscle mass during calorie restriction on incident mobility disability and physical function has yet to be studied.