Dr. Sharma's Obesity Notes

Readers of these pages are by now quite familiar with the increasing evidence showing that what happens to the fetus in utero may be a key determinant of obesity risk later in life. Thus, both small-for-gestational-age and large-for-gestational-age babies appear at increased risk for becoming obese kids (and adults).

One of the important determinants of infant weight is the magnitude of maternal weight gain in pregnancy. But how strong is this relationship really?

This question was now examined by David Ludwig (Harvard) and Janet Currie (Columbia) in a paper published last month in The Lancet.

The researchers examined data from a population-based cohort study that included all known births in Michigan and New Jersey, USA, between Jan 1, 1989, and Dec 31, 2003, or a total of 513 501 women and their 1,164,750 offspring.

Using a within-subject design to reduce confounding to a minimum, they noted a strong and consistent association between pregnancy weight gain and birthweight: infants of women who gained more than 24 kg during pregnancy were almost 150 g heavier at birth than were infants of women who only gained 8-10 kg.

Women who gained more than 24 kg during pregnancy were more than twice as likely to give birth to an infant weighing more than 4000 g than women who only gained 8-10 kg.

In light of the increasing evidence that larger infants are much more likely to become overweight and obese children (and later adults), this study certainly supports the need for efforts to prevent excessive weight gain during pregnancy.

Targeting obesity prevention and treatment strategies to younger women and limiting excessive weight gain during pregnancy, may well be the single most effective way to prevent obesity in future generations.

AMS
Edmonton, Alberta

Ludwig DS, & Currie J (2010). The association between pregnancy weight gain and birthweight: a within-family comparison. Lancet, 376 (9745), 984-90 PMID: 20691469

Today, I am going to throw out a bold statement on the state of overweight and obesity in Western societies: The time for primary prevention is over!

With two-thirds of the population now overweight or obese, we must accept that primary prevention has failed, the obesity horses are out of the the barn, there is no longer any point in locking the doors.

Rather, it’s now time to move on to secondary prevention; so let’s round up a posse and chase after the horses to catch them before they gallop off a cliff.

In developed countries around the world (including the US), we are beginning to see rates of overweight and obesity leveling off. This is not because these countries have now implemented strict measures to prevent obesity or to be taken as evidence that any such measures are working. I believe that the leveling off in the rates of overweight and obesity simply means that everyone in the Western world, who can be overweight or obese is now overweight or obese. The remaining third, that still has a normal weight, is overweight resistant and will never become obese, so let’s stop worrying about them.

Epidemiologists know, that in every epidemic comes a time when everyone who can be affected is affected. Even during the worst flu epidemic, a significant number of people will not come down with the flu no matter how much they are sneezed on or or how close they live to those who are affected. Yes, they may even have the virus circulating in their blood, but will yet have no sign of clinical disease nor will they develop it.

Obesity is no different. We are all exposed to the same societal factors that drive obesity. We are all surrounded by food (mostly unhealthy), we are all deprived of sleep, we all have sedentary jobs, we are all short of time, less than 5% of us eat the recommended diets or receive the recommended amount of daily activity. So why are we not all overweight or obese?

Because some of us are simply obesity resistant. For whatever reason (genetics, different metabolisms, distinct gut bugs, more brown fat, exercise addiction, etc.), some of us are either simply not obesity prone or are managing well to keep it at bay. Even if circumstances were to become more obesogenic, this proportion of our population would still not gain substantial amounts of weight - they are either truly (genetically) resistant, or would simply double their efforts to ward off those unwanted pounds - these people (I often refer to them as the “mutants”) will simply never become obese baring a catastrophe (e.g. an immobilising injury or illness, being put on an obesogenic drug, post-traumatic stress, severe depression, losing their income, etc.).

These are not the people we need to worry about. Educating them about the merits of eating healthier or being more active is a waste of time and resources - they are already eating just fine (or are resistant to their junk food diets) and are already getting plenty of exercise (or simply don’t need exercise because they are “natural-born” fidgeters). Any dollar spent on educating or incentivising them (e.g. tax breaks) is a dollar wasted.

Rather, it is now time to switch gears, time to call a spade a spade, and time to move on to secondary prevention. As my epidemiologist colleagues are well aware, in contrast to primary prevention, secondary prevention is not about preventing anyone from getting the condition; it is about ensuring that the problem does not get worse in the people who already have the problem.

Normally, in secondary prevention, you focus your efforts solely on the people who have the problem. However, when two-thirds of the population have it, you may as well treat the whole population, because making exceptions for those who don’t have the problem may simply not be practical. When most people have iodine deficiency, supplementing foods with iodine makes sense, even if this means that some people who do not need more iodine will get more iodine (thereby slightly increasing their risk for hyperthyroidism).

But moving to secondary prevention also means using different and more intense interventions. Thus in the secondary prevention of heart attacks, it is no longer simply enough to cut out the salt and add 20 mins of exercise to your day. After that first heart attack, you definitely want to make sure that your blood pressure and cholesterol levels are well controlled, even if this means increasing your dose of medications. And we are no longer talking about smoking less - no, after that heart attack, smoking is an absolute “no-no”.

Similarly, in the secondary prevention of obesity, simply eating more fruit and vegetables or walking more steps will not be enough. It is likely going to take far more drastic changes to your diet and to your activity levels to halt progression or reverse your condition. Effective weight management is neither easy nor simple (if it was simple for you, you’d be in the weight-resistant category in the first place). Now that you already have the problem, you will need special attention, special dedication, perhaps even special treatments to stop gaining more weight and hopefully lose some of that excess weight and keep it off. To some readers, secondary prevention may sound much more like treatment than prevention - this is because secondary prevention is in fact far closer to treatment than prevention.

Indeed, moving to secondary prevention requires a drastic rethinking in how we address the overweight and obesity epidemic at a population level. The question no longer is, how to help thin people stay thin. The question now is, how to help overweight and obese people not gain any more weight and perhaps receive treatments that will help them lose some of that excess weight and keep it off.

This may still mean we need to rebuild our neighbourhoods, deal with food insecurity, improve our diets, promote physical activity, and everything else that we should have done years ago at the first sign of the epidemic. But, because today we should no longer be worrying about primary prevention (which may have been easier had we actually done it), we will need far greater resolve and efforts to support far more radical changes at a societal level (not dissimilar the lengths we go to to remove peanuts from schools) to begin seeing clinically significant changes in weight at a population level - I purposely use the term “clinical”, because we now talking of disease control rather than disease prevention.

Skeptics may ask, “But what about the children? Is there not still time for primary prevention there?” To them my answer is that I do not for an instant believe that we will make a dent in the childhood obesity epidemic without first (or at least concurrently) addressing adult obesity (see previous post on this). Thus, probably the best primary prevention for childhood obesity simply takes us back to more secondary prevention for their parents.

Simply distributing more condoms in a population where most people already carry HIV is a waste of perfectly good condoms. It’s now time to put the anti-retrovirals in the drinking water.

AMS
Banff, Alberta

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As blogged previously, health-care professionals including physicians, nurses, psychologists, dietitians, fitness professionals, medical students, and even health professionals who specialise in obesity are often biased against obese people.

This anti-fat prejudice has direct implications for the health of those struggling with excess weight as it can increase vulnerability for depression, low self-esteem, anxiety, suicidality, maladaptive eating behaviors, avoidance of physical activity, poorer outcomes in behavioral weight loss programs, and hesitation to seeking preventive health-care services.

Perhaps one reason why health professionals are particularly prone to anti-fat prejudice, may be because conventional health education curricula tend to focus primarily on the importance of “controllable” lifestyle reasons for obesity, with health promotion/public health programs typically emphasizing dieting and physical activity as the cornerstones of obesity treatment and prevention. (see my previous posting: Does the Focus on Prevention Promote Weight Bias?)

Thus, the predominant focus on personal control may well increase the notion that people with excess weight simply lack willpower or are gluttonous and lazy.

This hypothesis was now tested by Kerry O’Brien (Manchester, UK) and colleagues in a paper just published online in OBESITY.

University students (n = 159; 85% females) enrolled in a health promotion/public health bachelors degree program were randomised to take part in one of three 12-week tutorials:

1) A discussion of research on common causes and treatments for obesity emphasizing personal responsibility and control (e.g., overeating and lack of exercise).

2) A discussion of genetics (biological predispositions/heritability) and socioenvironmental (e.g., the calorie-dense food environment) reasons for obesity providing research evidence and discussion on uncontrollable causes of obesity.

3) A discussion of research on rates of hazardous drinking in young people (16–24 years), its consequences, drivers, and reduction approaches. (this was the control group).

Before and after tutorials, participants were examined both for explicit bias (e.g. “I don’t like fat people much”, “Fat people tend to be fat pretty much through their own fault”) and implicit bias (using a test that examines participants tendencies to associate negative attributes (e.g., “bad,” “lazy”) with “obese/fat people,” or positive attributes (e.g., “good,” “motivated”) with “thin/slim people”).

The researchers hypothesised that those receiving training about the controllable causes of obesity (e.g., diet and exercise) will display increased anti-fat prejudice relative to the control participants.

Conversely, the researchers expected that those receiving information on the uncontrollable causes of overweight and obesity (i.e., genetics, environment) will show reduced anti-fat prejudice.

And this is pretty much exactly what the researchers found: While, the diet/exercise condition (traditional obesity-related health curriculum) showed a 27% increase in motivated/lazy implicit anti-fat prejudice, the genes/environment condition exhibited a 27% decrease in implicit “good/bad” anti-fat prejudice and a decrease of 12% in implicit “motivated/lazy” anti-fat prejudice (there was no change in the alcohol education group).

Given this evidence that emphasising the importance of “controllable” risk factors for obesity in the education of health professionals can increase their anti-fat bias, it is perhaps time to rethink health professional educations.

As the authors point out:

“…health educators should ensure that information on genetic, social and environmental causes of obesity, and their interactions, is delivered in a convincing manner along side traditional information on causes and treatments of obesity, such as diet and exercise.“

This study not only has implications for professional education but also for public health campaigns that tend to focus exclusively on diet and exercise while avoiding placing as much attention on genetic and non-controllable risk factors.

My own experience in presenting our recently published aetiological framework for obesity assessment to health professional audiences is consistently met with an often palpable change in attitude amongst my colleagues, many of whom have explicitly thanked me for opening their eyes to the complexity of this condition.

As long as we as health professionals do not address anti-fat bias amongst our peers, those struggling with excess weight will continue to suffer the consequences.

AMS
Edmonton, Alberta

O’Brien KS, Puhl RM, Latner JD, Mir AS, & Hunter JA (2010). Reducing Anti-Fat Prejudice in Preservice Health Students: A Randomized Trial. Obesity (Silver Spring, Md.) PMID: 20395952

Later today, Michelle Obama will step in front of the press in Washington to launch her initiative on addressing the childhood obesity epidemic in the US.

I am certain that she has no illusions as to the size of this challenge (no pun intended).

I will not go into details about the planned campaign or the considerable obstacles that she will need to overcome (for a thoughtful discussion of this go to the Canadian Press article by Nancy Benac).

Rather I’d like to turn my gaze to Canada and dare to ask the question: Where is the prominent Canadian public figure that is prepared to stand up and head a Canadian strategy to match Obama’s efforts?

If the US has an obesity problem, so do we!

If the US is now going to seriously take on this issue, so must we!

As Director of the Canadian Obesity Network, I can assure anyone willing to step forward that the Network with its over 4000 members and partners stands prepared to take up the challenge.

Any prominent Canadian public figure wishing to follow in Obama’s footsteps is welcome to simply step forward and drop me a line.

In the meantime, I will be carefully watching to see if the US initiative actually has enough support and teeth to really take on the countless interest groups and stakeholders that are perfectly happy with leaving things just the way they are.

Send me your comments on why you think so far no Canadian public figure has stepped forward to spearhead a campaign to address our own obesity epidemic and whether or not you think this would really make a difference.

AMS
Edmonton, Alberta

A widely held view is that the best solution to the current obesity epidemic is to focus on prevention and that if we only talk enough about it, increase our efforts to promote healthy lifestyles, get phys-ed back into schools, ban pizza-fundraisers, reduce advertising to kids, and get everyone to be more active, we will soon no longer have an obesity crisis.

This is not what the OECD believes, at least according to a report co-published by the World Health Organisation (WHO) last month.

I am referring to OECD HEALTH WORKING PAPERS No. 48 presented by the Health Committee of the Directorate for Employment, Labour and Social Affairs, titled: “Improving Lifestyles, Tackling Obesity: The Health and Economic Impact of Prevention Strategies”.

This report should make for some very sobering reading to all prevention enthusiasts.

The following the summary taken directly from this report:

In an attempt to contain rising trends in obesity and associated chronic diseases, many governments have implemented a range of policies to promote healthy lifestyles. These efforts have been hindered by the limited availability of evidence about the effectiveness of interventions in changing lifestyles and reducing obesity. Evaluations of the cost-effectiveness and distributional impacts of such interventions are even fewer and narrower in terms of numbers of options considered.

An economic analysis was developed jointly by the OECD and the WHO with the aim of strengthening the existing evidence-base on the efficiency of interventions to tackle unhealthy diets and sedentary lifestyles. The analysis was broadly based on the WHO-CHOICE (CHOosing Interventions that are Cost-Effective) approach, and it aimed at assessing the efficiency of a range of policy options to tackle unhealthy lifestyles and related chronic diseases. Additionally, compared to the traditional CHOICE framework, the analysis assessed the distributional impacts of preventive strategies on costs and health outcomes.

Most of the preventive interventions evaluated as part of the project have favourable cost-effectiveness ratios, relative to a scenario in which no systematic prevention is undertaken and chronic diseases are treated once they emerge.

However, since the determinants of obesity are multi-factorial and affect all age groups and social strata, interventions tackling individual determinants or narrowly targeted to one groups of individuals will have a limited impact at the population level, and will not reduce significantly the scale of the obesity problem.

Although the most efficient interventions are found to be outside the health sector, health care systems can have the largest impact on obesity and related chronic conditions by focusing on individuals at high risk.

Interventions targeting younger age groups are unlikely to have significant health effects at the population level for many years. The cost-effectiveness profiles of such interventions may be favourable in the long-term, but remain unfavourable for several decades at the start of the interventions.

Preventive interventions do not always generate reductions in health expenditure, when the costs of treating a set of diseases that are directly affected by diet, physical activity and obesity are considered.

As I said, a very sobering read for anyone who thinks obesity is preventable anytime soon.

AMS
Chicago, IL

Hat tip to Nathalie for bringing this report to my attention