|SSBs worse than an obesity pill?|
I had all that in the back of my head already, when I hit on a related "Pro v Con Debate" in the early views (articles that are not yet available in the print edition) of the Obesity Reviews and thought that you might be interest in some of the arguments F.B. Hu and K.A. Kaiser et al. are presenting in their "debate" (in fact we are talking about to separate position papers) on the "Role of sugar sweetened beverages in Obesity", as well.
Point: Sugar sweetened beverages, obesity & diabetes - Scientist says the evidence is there
(Hu. 2013) I would assume that the vast majority of you is not going to have to be convinced by rational or irrational arguments that sugar sweetened beverages will increase your risk of obesity and diabetes. Still, F.B. Hu, a scientists from the Departments of Nutrition and Epidemiology at the Harvard School of Public Health in Boston must have thought of the rest of the public and the bribed, ah... pardon "mislead" policy makers, when they compiled their latest paper with the tell-tale title "Resolved: there is sufficient scientiﬁc evidence that decreasing sugar-sweetened beverage consumption will reduce the prevalence of obesity and obesity-related diseases". According to Hu,
Hu also points to the "strong resistance from the beverage industry" and the few, but increasingly numerous public policies and regulatory strategies to reduce intake of SSBs that are already in place or being developed. The importance of a grass-roots approach, on the other hand appears to escape him. After all, it often does not look like this, but in the end the US is still a free country: You don't have to drink Pepsi, Coke and Mountain Dew, folks and neither do your friends and family.
Counterpoint: Sugar sweetened beverages are bad - in theory, but what about the reality?
(Kaiser. 2013) Now that your conviction that sugar sweetened beverages are bad, has been confirmed. let's shake the evidence and take a peak at what K. A. Kaiser, J. M. Shikany. K. D. Keating and D. B. Allison have to say about the question whether reducing sugar-sweetened beverage consumption will reduce obesity and why they feel that "[The e]vidence supporting conjecture is strong, but evidence when testing effect is weak".
Theory vs. experimental evidence: In fact the theoretical slope of the line depicting the increase in weight gain due to the consumption sugar sweetened beverages is more than 10x steeper than the one that has been observed in scientific studies (see figure 3).What is particularly interesting is that the theoretical prediction is accurate only in the lowest 10-15% of the SSB intakes investigated in the study, for the "real SSB junkies" the gab widens significantly.
|Figure 2: Rise in obesity rates (round markers) and bottled water consumption (square markers) in the US (Kaiser. 2013)|
This figure is yet not the only thing Kaiser at al. enlist to make you at least reconsider how conclusive the evidence of which Hu just argued that it is "there" actually is. The most important factors Kaiser, Shikany, Keating and Allison want to remind us of, when it comes to the interpretation and evaluation of the hitherto available studies are...
- the risk of bias -- Most scientists start out with the same conviction we do: "Sugar sweetened beverages make you fat!" Against that backround it is even more detrimental that "some study designs failed to adequately isolate treatment effects from the attention researchers paid to some groups." (Kaiser. 2013) The researchers also point out that not all studies had an objective measure of participant compliance (returned containers, urinary sucralose measures) and did not report whether the people who accessed the effects were blinded as well (10 out of 15 studies did not). Publication bias, on the other hand, did not appear to be a factor to skew the results (Kaiser. 2013)
- missing / insufficient sensitivity analysis -- In their re-analysis the researchers found sign. differences in the obesogenic effects of SSBs on young vs. old, male vs. female and lean vs. obese participants, yet the majority of the studies does not accordingly differentiate the outcomes.
Figure 3: Observed (30,34,40–42,62) versus theoretical (63) weight gain effect of mandatory sugar-sweetened beverage (SSB) consumption (Kaiser. 2013)
- data interpretation / analysis - The scientists suggest that analyzing only absolute weight / BMI levels is not an adequate measure and propose two different methods to evaluate the data
- Asking the question, whether a person that is in the "SSB" group would increase or decrease weight / BMI if he or she switched to the other group - This analysis yielded a +2% and +7% change of weight / BMI reduction.
- Using the correlation data as basis to calculate the explanatory value of SSB consumption - This analysis showed that only 1.92% of the variance in body weight or BMI change is explained by SSB consumption, for the variance weight reductions in persons of all weight categories the figure is a hilariously irrelevant 0.09%
Don't get me wrong, I love the "ads" of the NYC Dept. of Health & Mental Hygiene campaign against sugar sweetened beverages, and used it as title picture for a previous post on the fattening effects of SSBs, but they are part of the problem Kaiser et al. are pointing at in their paper. People will sit next to them think about the gym and say: "Well I drink diet coke, so I don't have to go to the gym today - after all sugar is the problem!"
Moreover, they likely raise emotions and impair logical reasoning. As Kersh and Morone wrote, ‘Scientiﬁc ﬁndings never carry the same political weight as does a villain threatening American youth.
If critics successfully cast portions of the industry in this way, far-reaching politi- cal interventions are possible, even likely. When an industry becomes demonized, plausible counterarguments (privacy, civil liberties, property rights, and the observation that “everyone does it”) begin to totter.’
- Distortion of scientiﬁc information - A second factor that has likely contributed to misperceptions in this area is the distortion of scientiﬁc information by some authors and commentators. [...] Clearly, such practices mislead and have likely contributed to misperceptions in the scientiﬁc and lay communities about the strength of the evidence regarding the proposition debated here.
- The mere exposure effect - The ﬁnal factor that we believe has led to the erroneous perception that the evidence showing that the proposition of this debate has been unequivocally proven is the ‘mere exposure effect.’
The mere exposure effect is the label psychologists use for the phenomenon that the more a person is exposed to an idea, the more they come to like and accept it. As the Nobel Prize-winning economist Daniel Kahneman described, ‘A reliable way to make people believe in falsehood is frequent repetition, because familiarity is not easily distinguished from truth. Authoritarian institutions and marketers have always known this fact. But it was psychologists who discovered that you do not have to repeat the entire statement of a fact or idea to make it appear true’
The number of articles on SSBs and obesity and the number of statements that SSBs are especially problematic in obesity are extraordinary, especially in comparison to the modest amount of probative data. Thus, opinions about SSBs may have been offered so often that these opinions have become accepted as fact by many in the scientiﬁc community, media and lay public.
Bottom line: I am well aware that some of you are now probably already dialing the Dr. Lustig's phone number or calling the blogosphere's vice police to accuse me of making a pact with the Coca Cola company.
|You all know I am an opponent of the consumption all sugar & HFCS sweetened drinks and foods and well aware of the "fat consequences" (learn more), but overemphasizing the roles of SSBs or HFCS, is not going to help us solve the global obesity problem.|
Still it is not warranted and would be a consequential mistake to expect that by taking them off the market the whole issue would be solved. We all know that this won't be the case and you just have to look at the non-existent long-term effects switching to diet sodas had on the waist lines of the obese to know that we have to do more than remove all sugar sweetened beverages from the displays of the supermarket.
Does this mean we should not tell people they are bad for them? Try to tax or ban them? No. What it does mean, though, is that the war against obesity is not a war against SSBs, only.
- Hu FB. Resolved: there is sufficient scientific evidence that decreasing sugar-sweetened beverage consumption will reduce the prevalence of obesity and obesity-related diseases. Obes Rev. 2013 Jun 13.
- Kaiser KA, Shikany JM, Keating KD, Allison DB. Will reducing sugar-sweetened beverage consumption reduce obesity? Evidence supporting conjecture is strong, but evidence when testing effect is weak. Obes Rev. 2013 Jun 7.