Wednesday, October 9, 2013

Do Public Health Professionals Need To Brush Up Their Knowledge of Basic Science?

sharma-obesity-caloric-balance1In a thoughtful paper published in BMC Medicine, Katherine Hafekost and colleagues from the University of Western Australia propose that the main reason why we have yet to see effective public health intervention to sustainably reduce obesity is because the champions of these policies largely ignore the basic scientific facts of human physiology.

Based on their systematic analysis of 27 article published in 2011 proposing public health interventions for obesity, the researchers found that all of these were based on a rather simplistic notion of energy balance. Despite acknowledging the complexity of obesity, the underlying philosophy of these public health approaches was essentially built around the idea that reducing caloric intake (diet) and increasing caloric expenditure (exercise) would result in long-term sustainable negative energy balance and thus result in a lower body weight.

As the authors note,

“Almost all the identified interventions focused on reducing energy intake, increasing physical activity, and reducing sedentary behaviors underpinned by an energy-balance model assuming independence between energy intake and expenditure, with little consideration of homeostatic feedback mechanisms.”

“Research from the fields of biochemistry and human physiology, which provides a more detailed model of energy balance, offers some insight into why many weight-loss interventions have little long-term success and poor program adherence….Although in the short term, food intake and energy expenditure are often influenced by situational factors, over longer time periods numerous neural and hormonal mechanisms operateto regulate body weight. Restrictions in caloric intake and/or increases in physical activity are likely to be matched by behavioral, metabolic, neuroendocrine, and autonomic changes that will limit long-term success.”

Given that body weight is tightly regulated and that our bodies will always “defend” against body weight loss, the best that public health measures can hope to achieve is to prevent further weight gain – they do not and cannot offer sustainable weight-loss.

“The failure of research in the field of public health to incorporate the concept of homeostatic feedback mechanisms into interventions is reflected in the current dietary guidelines, public health policy, and population-wide interventions aimed at targeting overweight and obesity.”

Although public health messages to eat healthier diets and reduce sedentariness no doubt have important cardiovascular and other benefits, when explicitly promoting reduced energy consumption and increased expenditure as the appropriate means by which to achieve weight loss, such measures pose ethical challenges.

“Despite the extensive literature on their long-term ineffectiveness, interventions based on this simplistic understanding of energy balance continue to be advocated under the assumption that previous interventions have not been pursued sufficiently vigorously or that participants have failed to follow the prescriptions of the intervention.”

“Continuing to promote a model that is unlikely to be successful in the longer term, and may result in individuals becoming discouraged, is both unproductive and wasteful of resources that could be better spent on investigating more plausible alternatives to improving weight control.”

I would add that the “energy-centric” model of obesity reduction not only fails to acknowledge the powerful homeostatic defences agains sustained weight loss but also generally fails to address the powerful psycho-biological drivers of weight gain.

Unfortunately, despite first eloquently arguing against overly simplistic “energy-balance” models of obesity interventions, the authors astonishingly still suggest that,

“The focus of future public health research should be on the development of large scale, long-term prospective studies that test dietary and exercise protocols that have been shown to be beneficial to weight loss and maintenance.”

I disagree! Enough effort and money has been spent on this.

I would much rather support their other recommendation, namely,

“..ensuring that funding or grant panels considering proposals for future intervention research include members trained in human biochemistry and physiology as well as public health advocates. This may assist in the development and implementation of appropriate research designs and methods that are underpinned by a complex model of energy balance.”

I also concur with the authors that, while,

“Currently, most research seems to address the question of what factors lead people to eat too much and exercise too little.”,

“Developing and testing interventions that are based on biologically plausible mechanisms [would be] an important step forward in developing effective interventions to combat obesity and its associated metabolic diseases.”

@DrSharma
Edmonton, AB

Hat tip to Cindy for pointing me to this paper.

ResearchBlogging.org
Hafekost K, Lawrence D, Mitrou F, O’Sullivan TA, & Zubrick SR (2013). Tackling overweight and obesity: does the public health message match the science? BMC medicine, 11 PMID: 23414295

 

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11 Responses to “Do Public Health Professionals Need To Brush Up Their Knowledge of Basic Science?”

  1. Leoluca Criscione says:

    …as anticipated in the book:

    “Eating healtyh and dying obese…elucidation of an apparent paradox”
    http://www.vitasanas.ch/wp/?page_id=370

    We have a chapter in the book: “Science feeds the confusion”!

    Removing the confusion in people’s mind, makes the difference! As our experience with Calogenetic Balance clearly indicates! http://www.vitasanas.ch/wp/wp-content/uploads/2013/06/poster-only-eco-liverpool-ok.pdf
    Kind regards fro mSwitzerland

  2. Elina Josephson says:

    The state of modern weight management reminds me of the pre-scientific magical thinking of the dark ages. It is stunning to me that well educated health professionals refuse to see what is consistently before their eyes. It is as if some prejudice or some fear keeps them from applying the clearly documented science that is so prevalent and accessible. Unlike you, I do believe that sustained weight loss is possible for many, but it requires a great deal more than the standard medical advice to eat less and move more. In my opinion, weight loss for the MO and SMO requires a metabolically active WLS, a great eating plan, a moving plan, a dedicated support system, CBT therapy and team of professionals. This, unfortunately, is not available to most people.

  3. rory robertson (former fattie) says:

    Dr Sharma,

    I agree with much of that. Importantly, that is why this “all you want to eat” diet – including foods that satisfy hunger and removing those which are more prone to fatten (most carbohydrates) has worked so effectively for over a century: (scroll down) http://www.australianparadox.com/pdf/why-we-get-fat.pdf

    We are left with plenty of energy and no gnawing hunger. That’s why low-carb works.

  4. Arya M. Sharma, MD says:

    I agree, Elina, that long-term weight loss is possible – but as you say it requires ongoing support that goes beyond “Eat-Less-Move-More”.

  5. Anonymous says:

    How about studying the incidence of Munchausen syndrome in obese patients seeking care from multiple medical specialties, from GP’s to psychologists to counsellors to dieticians to bariatric specialists.
    Here in Canada all that care is free in the health care system.

    If someone wants constant attention in a medical context, eating to the point of obesity is easier to do than faking or self-inflicting other conditions that give access to medical personnel. Not losing weight, or gaining more weight, is expected in treatment programs, so a patient can enlist medical resources indefinitely.

    Are there medical studies going on that seek to identify bariatric patients who are suffering from “Munchausen” syndrome?

    Does it even matter, if their medical care is giving them what they need?
    They’re definitely not going to lose weight, because then they’d also lose all medical attention, except maybe a few follow-up appointments. If what they need is to be cared for in a medical setting, then maybe what they’re getting is appropriate, even if they’re getting it by a roundabout method.

    1. Is it possible to identify Munchausen patients among the non-Munchausen-suffering bariatric patients?
    2. Would treatment be any different if Munchausen was identified?
    3. Would identification of Munchausen patients (whatever their treatment turns out to be) contribute to scientific understanding of obesity?

  6. DebraSY says:

    I don’t know which is the chicken and which is the egg: media or medicine, and both drive public policy (the farmer). Most GPs have a limited amount of time to devote to their medical research and every morning on the national news is another story promoting calorie balance — usually pegged on a research study and illustrated by a personal story from one individual who has lost a great amount of weight very recently and is still in the “If I can do it anyone can” phase. The doc goes off to work thinking “check” I heard a story about the most recent obesity research and it confirms what I have been preaching since 1978, now I’ll spend my research time looking at developments in Cancer, Lung Disease, etc.

  7. Arya M. Sharma, MD says:

    Beautifully said DebraSY – “usually pegged on a research study and illustrated by a personal story from one individual who has lost a great amount of weight very recently and is still in the “If I can do it anyone can” phase.” – So true – about to announce a new research study to the media tomorrow and here I am scrambling around looking for a patient willing to speak to the press. No patient – no story!

  8. rory robertson (former fattie) says:

    DebraSY,

    On obesity and cancer research, here’s a profound development. A ubiquitous substance that is a key driver of global obesity and type 2 diabetes – http://care.diabetesjournals.org/content/33/11/2477.full.pdf
    – probably also fuels cancers.

    I’m talking about our yummy friend refined sugar: v=xDaYa0AB8TQ&feature=youtu.be

    Between minutes 26 and 28 in the link above is prominent cancer researcher Louis Cantley, explaining why sugar is “scary”. He tries to eliminate added sugar from his diet. Food for thought? : http://www.youtube.com/watch?v=xDaYa0AB8TQ&feature=youtu.be

    Importantly, as with tobacco and alcohol, outsized rates of sugar consumption are a major driver of the unacceptable “gap” in life expectancy between Indigenous and non-Indigenous Australians: see the bottom row of Box/Table 2 in https://www.mja.com.au/journal/2013/198/7/characteristics-community-level-diet-aboriginal-people-remote-northern-australia

    Some of this growing disaster merely reflects the fact that sugar is cheap, available and yummy. But there appears also to be an addictive element to sugar, a dangerous addictive element that is helping to fuel global obesity, type 2 diabetes, heart disease and some cancers: http://www.youtube.com/watch?v=kVPmfMDFS9A

  9. Shane says:

    I am definitely a regular reader and a large fan of your opinion, it probably helps that I agree very much with the unbiased evidence and opinion that you put forth.
    I do however have a general question with respect to homeostatic feedback mechanisms.
    If homeostasis defends against weight loss would it not also defend against weight gain… would that not be the definitive outcome with a homeostatic mechanism?
    Thanks

  10. Arya M. Sharma, MD says:

    The homeostatic mechanisms do defend again weight gain but far less effectively than against weight loss. A typical defence mechanism against weight gain is fidgeting or an increase in non-exercise thermogensis. This allows some people to burn off the extra calories to maintain balance. Studies show that there is a wide variability in this – some people manage to fidget the extra calories off (upto 800 calories a day or more) – others do not. In practice we see short term changes in body weight (up or down) regulate themselves virtually without effort (e.g. the 4 pounds gained on a cruise or during a holiday). These pounds can quickly come off as soon as you return to your old lifestyle. Unfortunately, the system is heavily skewed towards defending against weight loss rather than protecting against weight gain – this is probably explained by evolution – until very recently, too much food has never been the problem.

  11. David Brown says:

    In my opinion, the problem is our modernized food supply. Low mineral content, high omega-6 content, and excessive added sugars content appear to be the main factors that derange appetite and alter homeostatic mechanisms responsible for fat gain.

    Industrial agriculture churns out commodities (mainly soybeans, corn, and wheat) that have reduced mineral content to begin with. After processing, the waste streams are further processed into livestock feedstuffs for chickens, cattle, swine, and fish. In the case of dried distillers grains with solubles (DDGS), a byproduct of ethanol production, the high omega-6 content boosts the omega-6 content of dairy, poultry, and meat. DDGS-fed animals fatten quickly and, although they don’t live long enough to develop cancers or heart disease, it can’t be all that healthy for them. http://www.pork.org/ResearchDetail/1370/default.aspx#.Ulqbm9cUyY0

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