There is no doubt that exercise is good for you and that individuals with obesity, both before and after bariatric surgery (like everyone else), would stand to benefit from increasing their levels of physical activity.
Following bariatric surgery, exercise may be particularly important not just to increase physical fitness, but also to limit the obligatory loss in muscle mass that generally accompanies weight loss.
Now, a study by David Creel and colleagues, published in OBESITY, compares three┬álevels of exercise intervention in patients following bariatric surgery in terms of effectiveness and adherence.
A total of 150 patients undergoing bariatric surgery were randomised to either┬ástandard care (SC), pedometer use (P), or exercise counseling group (C).
The standard care group (SC)┬áreceived no exercise support by the bariatric center beyond a simple┬áeducational pamphlet.
Participants in the pedometer group (P)┬áwere given a pedometer and a one-page information sheet on using the device to increase physical activity. This handout promoted the progressive attainment of 10,000 steps/day. Individuals were asked to wear their device daily and record date, steps achieved, and whether they wore the device the entire day, part of the day, or not at all. Journals were collected, but no feedback was provided.
Participants in the exercise counselling group (C) were regularly seen at the bariatric centre and counselled by a certified exercise professional using motivational intervention techniques with individual goal setting.
Based on physical activity measurements using an accelerometer over two weeks before and┬á2, 4, and 6 months postoperatively, there was no difference between the SC and P groups, with a statistically significant but modest increase in daily steps in the C group that emerged at 4 months and was maintained at 6 months (about 1,000 extra steps per day compared to SC).
There was no notable difference in exercise tolerance, which increased in all three groups post surgery.
No group┬áreached the 10,000 steps/day or 150 bout-minutes/week recommended for general health
As may be expected from these rather modest results, no┬ásignificant differences in weight or weight change were found between groups at any time point.
Thus, these findings suggest that handing out a pedometer and asking patients to journal their activity is no more effective┬áin promoting physical activity, than simply handing out a pamphlet; moreover, even adding in counselling by an exercise professional adds little (if anything) to the outcome.
Although the researchers discuss the possibility that an even more intense intervention may provide more benefit, the modest findings certainly question the effectiveness of activity interventions post surgery.
Certainly, simply handing out pedometers does nothing, and adding in expensive group meetings or meetings with exercise professionals adds little more.
These finding by no means speak against the value of exercise after bariatric surgery – they just speak against the indiscriminate use of expensive healthcare resources, when they achieve little more than can be achieved by handing out a pamphlet.
Now a paper by James Mitchell and colleagues, published in JAMA Surgery, reports on the postoperative eating behaviors and weight control strategies that are associated with differences in body weight seen at 3 years after bariatric surgery.
The study looks at┬áself-reported data from over 2000 participants in the The Longitudinal Assessment of Bariatric Surgery-2 (LABS-2) study, a multicenter observational cohort study at 10 US hospitals in 6 geographically diverse clinical centers in the USA. Participants completed detailed surveys regarding eating and weight control behaviors prior to surgery and then annually after surgery for 3 years.
The researchers assessed 25 postoperative behaviors related to eating, weight control practices, and the use of alcohol, smoking, and illegal drugs.
The three key behaviours associated with poor outcomes were lack of weekly self-weighing, continuing to eat when feeling full more than once a week, and eating continuously during the day.
Thus, a participant who postoperatively started to self-weigh regularly, stopped eating when feeling full, and stopped eating continuously during the day after surgery would be predicted to lose almost 40% of their baseline weight compared to only 24% weight loss in participants who did not adopt these behaviours.
Other behaviours that had negative influences on outcomes included problematic use of alcohol, smoking and illegal drugs.
Thus, as one may have suspected all along, helping patients adopt and adhere to behavioural changes that include self-montioring and mindful eating behaviours can be expected to substantially affect the success of bariatric surgery.
Seoul, South Korea
Melanocyte-stimulating hormone (a-MSH), which is produced from the hormone precursor proopiomelanocortin (POMC) and acts on the hypothalamic melanocortin-4 receptor, plays a key role in the regulation of satiety and energy expenditure.
In very rare instances, mutations of the gene coding for POMC can cause severe early onset obesity characterised by increased appetite. Due to other effects of POMC deficiency, patients will present with pale skin, red hair and clinical signs of hypocortisolism.
Now, a paper by Peter K├╝hnen and colleagues published in the New England Journal of Medicine, shows that treating patients with the melanocortin-4 receptor agonist, setmelanotide, can result in significant reduction in appetite and body weight.
The open-label study was performed in two adult patients with POMC deficiency, in cooperation with Rhythm Pharmaceuticals, which provided the study medication and regulatory support.
Both patients weighed around 150 Kg with marked hyperphagia and both responded to treatment with a substantial reduction in appetite and dramatic weight loss of over 20 Kg over 12-13 weeks.
After a brief interruption, one patient was again treated for 42 weeks, ultimately losing 51 kg (32.9% of her initial body weight).
As the authors note,
“Setmelanotide appeared to completely reverse hyperphagia, leading to impressive weight loss and normalization of insulin resistance. More important, both patients reported a dramatic improvement in their quality of life after the initiation of setmelanotide therapy. Moreover, the substantial and ongoing reduction in body weight was similar to the changes observed after leptin administration in patients with leptin deficiency.”
Over all the treatment was well tolerated with no major adverse effects.
While these observations were made in very rare patients with documented POMC deficiency, these findings may have broader implications for individuals with more common “garden-variety” obesity.
“Both patients described here had very high leptin levels before treatment, suggesting leptin resistance. In patients with proopiomelanocortin deficiency, the leptin signal is probably not properly transduced into anorexigenic responses, given the lack of melanocyte-stimulating hormone. Setmelanotide substitutes for melanocyte-stimulating hormone and binds at its receptor, thus overcoming leptin resistance. On the basis of the observation that obese patients without known genetic abnormalities have severe leptin resistance and regain weight owing to a post-dieting increase in appetite, we speculate that setmelanotide may also be effective in nongenetic forms of obesity.”
Appropriate studies in patients with non-POMC deficient obesity are currently underway.
Regular readers will be well aware of the┬áEdmonton Obesity Staging System┬á(EOSS), which classifies individuals living with obesity according to the presence and severity of medical, mental and functional complications on a 5-point ordinal scale.
We have┬ápreviously shown┬áthat EOSS provides a better assessment of mortality risk than BMI, waist circumference, or the presence of metabolic syndrome.
Now, a paper by Sonja Chiappetta and colleagues from Offenbach, Germany, published in┬áSOARD, shows that EOSS strongly predicts early surgical complications and mortality in patients undergoing bariatric surgery.
The authors analysed data from 534 patients, collected prospectively, for patients undergoing laparoscopic sleeve gastrectomy (LSG), laparoscopic Roux-en-Y gastric bypass (LRYGB), or laparoscopic omega-loop gastric bypass (LOLGB).
As typical for a bariatric surgery population, the mean BMI was around 50 kg/m2.
While the total postoperative complication rate for the entire patient sample was 9%, the complications rates were 0% for patients with EOSS Stage 0 (5% of patients), 1.6% for Stage 1 ( (12%), 8% for Stage 2 (71%), 22% for Stage 3 (13%) and 100% for Stage 4 (0.2%).
There was no significant difference in BMI levels across EOSS stages and not consistent association of EOSS stage with age.
From these findings the authors conclude that,
“Patients with EOSSÔëÑ3 have a higher risk of postoperative complications. Our data confirm that the EOSS is useful as a scoring system for the selection of obese patients before surgery and suggest that it may also be useful for presurgical stratification and risk assessment in clinical practice. Patients should be recommended for obesity surgery when their EOSS stage is 2 to prevent impairments associated with metabolic disease and to reduce the risk of postoperative complications.”
Thus, following weight loss, not only does the body need fewer calories, doing┬áthe same amount of physical work uses┬áfewer calories than before (the joke is that, if you ran 5K a day to lose weight, you have to run 10K a day to keep it off).
Now, a study by┬áMaria┬áFernstr├Âm and colleagues, published in Obesity Surgery, shows increased mitochondrial efficiency following bariatric surgery.
The researchers performed skeletal muscle biopsies in 11 women before and at 6┬ámonths after gastric bypass surgery.
Measurements in isolated mitochondria showed a marked increase in coupled respiration (state 3) and overall mitochondrial capacity (P/O┬áratio) with a non-significant increase in uncoupled (state 4) respiration.
Thus, at 6 months following gastric bypass surgery, both the mitochondrial capacity for coupled, i.e., ATP-generating, respiration increased as well as┬áthe┬áP/O┬áratio improved.
As the authors note, not only would this increased “fuel efficiency” in part┬áexplain the decreased basal metabolism often associated with weight loss but also the propensity for weight regain that often follows weight-loss interventions.
Obviously, due to lack of a control group, this study does not demonstrate that these changes are in any way specific to weight-loss following bariatric surgery.
Also, given that the nadir of weight loss is generally not achieved until about 18 months following surgery, the changes observed in this study may not represent the maximum increase in mitochondrial efficiency to be achieved with further weight loss.