The other side of the soda/fat scare story

"Americans have sipped and slurped their way to fatness by drinking far more soda and other sugary drinks over the last four decades, a new scientific review concludes," reported the Associated Press this week. It's too bad that the AP didn't report the full story as told -- and yet, not told -- in the review itself, rather than apparently just regurgitating the researchers' media release.

Published in the American Journal of Clinical Nutrition (August 2006), the researchers reviewed 30 studies published from 1966-2005 and made a judgment call to the effect that, "The weight of epidemiologic and experimental evidence indicates that a greater consumption of [sugar-sweetened beverages] is associated with weight gain and obesity." That's the media-ready, quick-and-dirty message that the AP and other reporters latched onto for alarmist headlines.

But the researchers acknowledge in their review article that, "Despite our overall findings of a positive association between sugar-sweetened beverage consumption and weight gain and obesity, other investigators have suggested that such a relation does not exist. Multiple studies. did not find a significant association between consumption of soda or fruit drinks and [weight gain] in American children and adolescents." The researchers concede that, "interpretation of the published studies is complicated by several method-related issues, including small sample sizes, short duration of follow-up, lack of repeated measures in dietary exposures and outcomes, and confounding by other diet and lifestyle factors."

So there is clearly another side to the story that is nowhere to be found in this week's headlines. That other side not mentioned in the AJCN study includes a 2002 report from the National Academy of Sciences' Institute of Medicine that reviewed 300 studies -- 10 times more studies than were reviewed in the AJCN study -- and concluded, "There is no clear and consistent association between increased intake of added sugars and [body weight]." The AJCN study also omits mention of a May 2005 article in the journal Obesity Reviews that concluded, "Overweight status was not associated with the intake of fruits, vegetables, and soft drinks or time spent on the computer." The Obesity Reviews study involved 137,593 adolescents -- more than the total number of study subjects and more than twice the number of adolescents than included in all 30 studies in the AJCN study.

As if omission of these pertinent facts weren't bad enough, the researchers and AP reporter added insult to injury by summarizing the review with this outlandish sound-bite: "An extra can of soda a day can pile on 15 pounds in a single year, and the `weight-of-evidence' strongly suggests that this sort of increased consumption is a key reason that more people have gained weight."

While it's certainly true that the caloric content of 365 sodas (of 140 calories each) equates to about the caloric content of 15 pounds of body fat, it's not true that merely consuming one soda per day will translate to a 15-pound weight-gain over one year or that skipping one soda per day will translate to a 15 pounds weight-loss over one year. Bodyweight results from complex interactions between metabolism and lifestyle. An August 2004 study, for example, examined data on 1,007 women who increased their consumption of soda over a period of four years from less than one soda per week to one or more soda per day. After increasing their soda consumption at least 7-fold over a period of 4 years, the women only gained an average of 10.3 pounds. But according to the sort of mindless math espoused by the AJCN study's researchers, the women should have gained as much as 60 pounds. Obviously the notion that soda consumption goes straight to, or comes straight off, one's hips is wrong.

Even more interesting is the tie-in between the ACJN study and the August 2004 study - namely Harvard University researcher, Dr. Frank Hu, who led both studies. Though knowing through his own research that the 15-pounds-per-year factoid is wrong, he nevertheless sanctioned it for media consumption. Dr. Hu has a history of attempting to link soda with various health endpoints, including pancreatic cancer, diabetes, and weight gain - all of which are long on alarm, but short on science. It is, therefore, not surprising that Dr. Hu reached the conclusion he did in the AJCN study. Given the conflicting nature of the statistical studies on soda consumption and weight gain - which calls into question the notion of any general link between soda consumption and weight-gain - Dr. Hu could have concluded that it's premature to draw conclusions and that more research is necessary to definitively resolve the issue. Instead, Dr. Hu surrendered to his seemingly built-in bias against soda -- drawing a much over-blown conclusion, knowingly serving up a patently absurd sound-bite to incurious media and asking for more taxpayer money for research. The AJCN study fiasco gives a whole new meaning to "soda jerk."

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