At the recent European Congress on Obesity, I had the occasion for a long chat with my friend and colleague Abdul Dulloo, from Friburg in Switzerland, who has worked extensively on the issue of weight regain.
I asked him how much evidence there is to support the common notion that losing weight makes you fatter – something many dieters claim to have experienced.
Indeed, both in animals and humans, weight loss, as a rule, is followed by a more rapid regain of body fat than lean body mass (i.e. preferential catch-up fat) than of lean body mass, as a result of which body composition post-weight regain results in a greater proportion of fat mass than before. But does this increased “fatness” persist over time?
This is where Dulloo made me aware of a recent paper he published in Obesity Reviews that examines this question.
What his analysis of prospective studies on this issue revealed is that paradoxically, people within a the normal weight range appear much more prone to weight gain over time with dieting than people who already have overweight or obesity.
Indeed as he points out,
“…it is dieting to lose weight in people who are in the healthy normal range of body weight, rather than in those who are overweight or obese, that most strongly and consistently predict future weight gain.”
The reasons for this rather unexpected finding are unclear and some have argued that repeated dieting to lose weight in normalweight people may represents unsuccessful attempts to counter genetic and familial predispositions to obesity – these people are genetically prone to weight gain, which is why they are dieting in the first place. Thus, rather than a causal relationship, the association between dieting and subsequent weight gain is just what would have happened to them anyway.
Others have argued that the metabolic effects resulting from the psychological “fear of fatness” (which prompts dieting) per se may increase the risk for weight gain hence a contributing factor to the obesity epidemic.
However, as Dulloo and colleagues discuss at length, based on their reanalysis of a wide range of human studies of weight loss and refeeding on body composition data on fat mass and fat-free mass (FFM) losses and regains, there is increasing support for the biological plausibility that dieting predisposes lean individuals (rather than those with overweight or obesity) to regaining more body fat than what had been lost (i.e. fat overshooting).
Overall the findings suggest that perhaps the reason why lean people regain fat faster is because their feedback signals in response to the depletion of both fat mass (i.e. adipostats) and fat-free mass (i.e. proteinstats), through the modulation of energy intake and adaptive thermogenesis, are more effective than in individuals with overweight or obesity, thus resulting in a faster rate of fat recovery relative to recovery of lean tissue (i.e. preferential catch-up fat).
In fact, it appears that lean people overshoot in terms of weight gain because the state of hyperphagia (in response to weight loss) appears to persist well beyond complete recovery of fat mass and interestingly until fat free mass is fully recovered (which may take months during which time fat gain continues).
Thus, it appears that in lean individuals “fat overshooting” following a diet is a prerequisite to allow complete recovery of fat-free mass (in obese individuals this may be less of an issue as recovery of fat-free mass is stimulated simply by the need to carry around a greater body weight).
Thus, it is easy to understand why repeated dieting and weight cycling would increase the risks for trajectories from leanness to fatness particularly in people who have a normal weight to begin with.
These findings have important public health implications and for promoting a “fear of fat”.
As Dulloo notes,
“Given the increasing prevalence of dieting in normal-weight female and male among young adults, adolescents and even children who perceive themselves as too fat (due to media, family and societal pressures), together with the high prevalence of dieting for optimizing performance among athletes in weight-sensitive sports, the notion that dieting and weight cycling may be predisposing a substantial proportion of the population to weight gain and obesity deserves greater scientific scrutiny.”
Indeed, I wonder how much of the obesity epidemic is directly attributable to normal weight people trying to lose weight for no good reason other than to look better.
Dulloo AG, Jacquet J, Montani JP, & Schutz Y (2015). How dieting makes the lean fatter: from a perspective of body composition autoregulation through adipostats and proteinstats awaiting discovery. Obesity reviews : an official journal of the International Association for the Study of Obesity, 16 Suppl 1, 25-35 PMID: 25614201
If you are planning to attend the 4th Canadian Obesity Summit in Toronto next week (and anyone else, who is interested), you can now download the program app on your mobile, tablet, laptop, desktop, eReader, or anywhere else – the app works on all major platforms and operating systems, even works offline.
You can access and download the app here.
(To watch a brief video on how to install this app on your device click here)
You can then create an individual profile (including photo) and a personalised day-by-day schedule.
Obviously, you can also search by speakers, topics, categories, and other criteria.
Hoping to see you at the Summit next week – have a great weekend!
Given that most people do not look at obesity as a chronic disease that requires professional management, the most common approach to losing weight is still for people to try to lose weight on their own.
But just how effective are these do-it-yourself approaches to weight management?
This is the topic of a systematic review and meta-analysis by Jamie Hartmann-Boyce and colleagues from Oxford University, published in the American Journal of Public Health.
Self-help programs were defined as self-directed interventions that do not require professional input to deliver (“self-help”) across a variety of formats, including but not limited to print, Internet, and mobile phone-delivered programs.
As such programs come in all shapes and sizes, the researchers also distinguished between “tailored” interventions as those in which participant characteristics were used to provide individualized content (e.g., tailored based on information provided by participants at baseline), and “interactive” interventions as those programs in which participants could actively engage with intervention content (e.g., through online quizzes or entering their own content).
For each intervention, the authors also coded the specific type of self-managment strategies ranging from goal setting to buddy systems.
The researchers found 23 randomized controlled trials comparing self-help interventions with each other or with minimal controls in overweight and obese adults, with 6 months or longer follow-up. Together these studies included almost 10,000 participants in 39 intervention arms.
Although the researchers noted considerable heterogeneity among studies, the average difference in weight loss at 6 months between the self-management and control groups was about 2 Kg, an effect that was no longer significant at 12 months.
Overall the type of program (tailored vs. non-tailored, interactive vs. non-interactive, etc.) did not make any notable difference to the success of participants.
The authors also noted that the only trial that examined a potential interaction with socioeconomic status found that the intervention was more effective for more advantaged populations.
Despite these rather sobering results, the authors come to the rather astonishing conclusion that,
“Results from this review show promising evidence of the effectiveness of self-help interventions for weight loss.”
“Public health practitioners and policymakers should look to implement self-help interventions as a component of obesity intervention strategies because of the high reach and potentially low cost of these programs.”
How exactly, the authors would come to these recommendations is unclear – my view would be that this could be a rather substantial waste of public health funding that could probably be put to much better use.
Based on this paper (despite the enthusiastic conclusions of the authors), my conclusion would be that the vast majority of current self-management programs are probably not worth the time or effort.
This is not to say that self-management does not have an important role in obesity management – it certainly does, but evidently needs to occur under professional guidance.
So, if you do have a medically relevant weight problem – get professional help!
Hartmann-Boyce J, Jebb SA, Fletcher BR, & Aveyard P (2015). Self-Help for Weight Loss in Overweight and Obese Adults: Systematic Review and Meta-Analysis. American journal of public health PMID: 25602873
The latest addition, just approved by the US FDA for the treatment of obesity in adults with a BMI of 40 to 45 kg/m2 or a BMI of 35 to 39.9 kg/m2 with a related health condition, is something I’ve posted about before - VBLOC or the vagal “pacemaker” as it is sometimes referred to.
Indeed, Enteromedics‘ rechargeable Maestro system is very much like an implantable cardiac pacemaker, in that it delivers an electronic signal – in this case to block the action of the vagus nerve. The exact mode of action is not entirely clear but the weight-loss mediating effect (in the 10-15% average range) is largely a result of reduced appetite and increased satiety.
Here is how Enteromedics describes its system:
“The Maestro® System consists of a subcutaneously implanted rechargeable neuroregulator and two electrodes that are laparoscopically implanted by a bariatric surgeon. It delivers VBLOC® vagal blocking therapy via these electrodes that are placed in contact with the trunks of the vagus nerves just above the junction between the esophagus and the stomach. The device intermittently blocks vagal nerve signals throughout the patient’s waking hours. The Maestro System is recharged using an external mobile charger and transmit coil worn by the patient. The device can be non-invasively programmed, and it can be adjusted, deactivated, reactivated or completely removed if desired.”
Obviously this is far from the be-all and end-all of obesity treatments – especially as it does not seem to work for everyone. Thus, the recently published results from the pivotal study (discussed here), was certainly far less impressive than the company may have hoped for.
Just where VBLOC treatment will ultimately find its place in bariatric care remains to be seen – this is certainly a space to watch.
Regular readers may recall past posts on the use of intermittent electrical blockade of the vagus nerves (VBLOC) as a means of reducing food intake to promote weight loss.
Now a large randomised controlled study of vagal blocakade, published by Sayeed Ikramuddin and colleagues, published in JAMA, reports on rather disappointing outcomes with this treatment.
In this study (ReCharge), conducted at one of 10 sites in the United States and Australia between May and December 2011, 239 participants with a BMI greater than 40 (or greater than 35 with at least one comorbidity), were randomised to receiving an active vagal nerve block device (EnteroMedics’ Maestro® Rechargeable (RC) System, n=162) or a sham device (n=77).
Over the 12-month blinded portion of the 5-year study (completed in January 2013), the vagal nerve block group lost about 9% or their initial body weight compared to only 6% in the sham group.
In addition to this rather modest difference in weight loss between the groups (about 3%), participants in the active treatment group also experienced a number of clinically relevant adverse effects (heartburn or dyspepsia and abdominal pain).
Thus, overall these rather disappointing results are in line with the previously disappointing observations in the smaller MAESTRO trial.
Based on these findings, it seems that intermittent electrical blockade of the vagal nerve may not hold its promise of a safe and effective long-term treatment for severe obesity after all.
Ikramuddin S, Blackstone RP, Brancatisano A, Toouli J, Shah SN, Wolfe BM, Fujioka K, Maher JW, Swain J, Que FG, Morton JM, Leslie DB, Brancatisano R, Kow L, O’Rourke RW, Deveney C, Takata M, Miller CJ, Knudson MB, Tweden KS, Shikora SA, Sarr MG, & Billington CJ (2014). Effect of reversible intermittent intra-abdominal vagal nerve blockade on morbid obesity: the ReCharge randomized clinical trial. JAMA, 312 (9), 915-22 PMID: 25182100