I have long postulated that the benefits of exercise in weight management have little to do with burning calories. Rather, I am pretty sure that when people lose weight with exercise, they do so because of the impact that exercise may have on their food intake (I call it exercising to ruin your appetite!).
Thus, I am happy to acknowledge my affirmation bias in paosting about the recent study by Larissa Ledochowski and colleagues from the University of Innsbruck, Austria, published in PLOS One on the outcome of a randomised controlled trial of brisk walking on cravings for sugary snacks.
The study was conducted in 47 overweight volunteers who reported habitually consuming a fair share of sugary snacks. Following 3 days of “chocolate abstinence” subjects were randomised (using a within-subject design) to a 15-min brisk walk or passive control.
On each occasion, subjects were then stressed using the Stroop color–word interference task after which they reported their urges for sugary snacks using the State Food Craving Questionnaire [FCQ-S] adapted for sugary snacks.
Compared to the control situation, brisk walking resulted in a significant and relevant reduction in the urge for sugary snacks and attenuated the increase in sugar-cravings under trigger conditions (stress).
Although the authors are careful about not over-interpreting their findings from this acute study (that did not actually measure sugary-snack intake), they do make the following speculation regarding clinical relevance,
“This study adds to the increasing evidence that physical activity can somehow help to regulate the urge to consume snack food. It may be easy for overweight people to fit in short bouts of low-moderate intensity physical activity, instead of being sedentary, to elevate affective activation and valence and reduce high energy food cravings which may be triggered by stress and the presence of snack foods.”
While I am certain that more intense exercise may well trigger a hunger response, it appears that even a short bout of brisk walking may help dispel those cravings for sugary snacks (let me know if you have experienced this).
In last week’s 2015 Lancet series on obesity, the majority of papers focus on policy interventions to address obesity. It suggests that a reframing of the obesity discussion, that avoids dichotomies (like nature vs. nurture debates) may provide a path forward – both in prevention and management.
The policy framework presented by Christina Roberto and colleagues in The Lancet, is based on the NOURISHING framework, proposed by the World Cancer Research Fund International to categorise and describe these actions.
Together, the actions in this framework address the food environment (e.g. food availability, taxation, restrictions on advertising, etc.), food systems (e.g. incentives and subsidies for production of healthier foods) and individual behaviour change (e.g through education and counselling).
This “food-centric” view of obesity is complemented by recognising that physical activity, much of which is dictated by the built environment and captivity of the population in largely sedentary jobs, also has a role to play.
On a positive note, the Christina and colleagues suggest that there may be reasons for careful optimism – apparently 89% of governments now report having units dedicated to the reduction of non-communicable diseases (including obesity), although the size and capacity of many of these units is unknown.
On the other hand, despite an increasing number of such efforts over the past decades, no country has yet reversed its epidemice (albeit there is a flattening of obesity growth rates in the lower BMI ranges in some developed countries – with continuing rise in more severe obesity).
Despite the potential role of government policies in reducing non-communicable diseases (including obesity) by “nudging” populations towards healthier diets and more physical activity, the authors also note that,
“…the reality is that many policy efforts have little support from voters and intended programme participants, and although the passage of policies is crucial, there is also a need to mobilise policy action from the bottom up.”
Indeed, there is growing list of examples, where government policies to promote healthy eating have had to be reversed due to lack of acceptance by the public or were simply circumvented by industry and consumers.
Nevertheless, there is no doubt that policies in some form or fashion may well be required to improve population health – just how intrusive, costly and effective such measures will prove to be remains to be seen.
All of this may change little for people who already have the problem. As the article explains,
“There are also important biological barriers to losing excess weight, once gained. Changes in brain chemistry, metabolism, and hunger and satiety hormones, which occur during attempts to lose weight, make it difficult to definitively lose weight. This can prompt a vicious cycle of failed dieting attempts, perpetuated by strong biological resistance to rapid weight loss, the regaining of weight, and feelings of personal failure at the inability to sustain a weight-loss goal. This sense of failure makes people more susceptible to promises of quick results and minimally regulated claims of weight loss products.”
Not discussed in the article is the emerging science that there may well be other important drivers of obesity active at a population level that go well beyond the food or activity environment – examples would include liberal use of antibiotics and disinfectants (especially in agriculture), decreased sleep (potentially addressable through later school start times and mandatory afternoon naps in childcare settings), increasing maternal age at pregnancy (addressable by better access to childcare), time pressures (e.g. policies to address time-killing commutes), etc.
Perhaps what is really needed is a reframing of obesity as a problem where healthy eating and physical activity are seen as only two of many potential areas where policies could be implemented to reduce non-communicable diseases (including obesity).
Some of these areas may well find much greater support among politicians and consumers.
For all my Canadian readers (and any international readers planning to attend), here just a quick reminder that the deadline for early bird discount registration for the upcoming 4th Canadian Obesity Summit in Toronto, April 28 – May 2, ends March 3rd.
To anyone who has been at a previous Canadian Summit, attending is certainly a “no-brainer” – for anyone, who hasn’t been, check out these workshops that are only part of the 5-day scientific program – there are also countless plenary sessions and poster presentations – check out the full program here.
To register – click here.
In 2011, The Lancet dedicated a special issue to the topic of obesity – the general gist being that obesity is a world wide problem which will not be reversed without government leadership and will require a systems approach across multiple sectors. The Lancet also noted that current assumptions about the speed and sustainability of weight loss are wrong.
This week, The Lancet again dedicates itself to this topic with ten articles that explore both the prevention and management of obesity.
According to Christina Roberto, Assistant Professor of Social and Behavioural Sciences and Nutrition at the Harvard T H Chan School of Public Health and a key figure behind this new Lancet Series, “There has been limited and patchy progress on tackling obesity globally”.
Or, as Sabine Kleinert and Richard Horton, note in their accompanying commentary, “While some developed countries have seen an apparent slowing of the rise in obesity prevalence since 2006, no country has reported significant decreases for three decades.”
As Kleinert and Horton correctly point out, a huge part of this lack of progress may well be attributable to the increasingly polarised false and unhelpful dichotomies that divide both the experts and the public debate, thereby offering policy makers a perfect excuse for inaction.
These dichotomies include: individual blame versus an obesogenic society; obesity as a disease versus sequelae of unrestrained gluttony; obesity as a disability versus the new normal; lack of physical activity as a cause versus overconsumption of unhealthy food and beverages; prevention versus treatment; overnutrition versus undernutrition.
I have yet read to read all the articles in this series and will likely be discussing what I find in the coming posts but from what I can tell based on a first glance at the summaries, there appears to be much rehashing of appeals to governments to better control and police the food environments with some acknowledgement that healthcare systems may need to step up to the plate and do their job of providing treatments to people who already have the problem.
As much as I commend the authors and The Lancet for this monumental effort, I would be surprised if this new call to action delivers results that are any more compelling that those that followed the 2011 series.
I can only hope I am wrong.
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