Soda, Calories, and a Full Accounting

Calorie counts are coming to soda vending machines in two states. Will this make a difference?

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The American Beverage Association (ABA) announced this week, with predictable fanfare, its plans to put calorie counts on soda vending machines in San Antonio, Texas, and Chicago, Ill. In principle, national expansion will follow, but those details are not yet in place. For now, the program can only do good so far as it goes geographically. The question then is: What good is that? What, exactly, will soda calorie counts do for the San Antonians and Chicagoans, as the rest of us watch from the sidelines?

We don't really know for sure. Studies of calorie count postings to date have yielded rather mixed results. There is some evidence to suggest that calorie counts on foods and beverages do give consumers pause, and a bracing reality check. These, in turn, may help dial down total calorie intake.

But that effect is by no means established. In some cases, calorie counts appear to evoke defiance (or denial) rather than temperance. And there is some evidence to suggest that calories avoided at one time may simply find their way back into the diet at another. There is, as well, some research evidence that when people expect to be left hungry—a potential effect of a low-calorie count on display—that hormones respond accordingly, making the expectation a self-fulfilling prophecy. Maybe a bit of ignorance is the belly's bliss.

In other words, calories count, but they are by no means the only thing that does. Accounting for other aspects of nutrition is crucial. As is accounting for taste.

Many of the products that will appear in calorie-labeled, soft drink vending machines will be diet sodas, and variations on that theme. Diet sodas may have no calories, so on a calories-only scale, they will look the same as water. They are not.

The diet sodas that presently prevail in the market use sugar substitutes, or "artificial" sweeteners, that range from 600 to 1,300 times the sweetness intensity of sugar. If high calorie counts are expected to talk people out of a choice, it stands to reason that low calorie counts could presumably talk people into one. Diet sodas are apt to be a prominent beneficiary of this.

The potential trouble with this scenario is nicely captured by the way we often refer to a penchant for desserts: We call it a "sweet tooth." That's important. We don't call it a "sugar tooth," and we are quite right. Our taste buds register sweet, not sugar, and can't reliably differentiate sweetness coming from sucralose or saccharin, agave or aspartame. Sweet is sweet.

And sweet from any source seems to have the same potential to grow a sweet tooth into a sweet … fang. There is much discussion in both the scientific literature and popular press now about the potential addictive properties of food, with sugar at the top of the list. But we don't really mean that sugar is addictive—we mean that "sweet" is. The more sweet there is in your diet, the more you need to be satisfied. This effect is well established, and to the best of our collective knowledge, results equally from sugar with calories and artificial sweeteners without.

Even so, no-calorie artificially sweetened sodas might still be a good thing if they took calories and sugar out of our diets and left us without good ways of putting it back. But the very opposite is true; we have almost unlimited ways of adding back those calories and sugar.

For example, there are pasta sauces on every supermarket shelf in the country with a higher concentration of added sugar than is found in ice cream topping, literally (yes, I've done the math). Ditto for salad dressings. There are also breads, crackers, spreads, nut butters, and even chips with added sugar—and there are, of course, dessert options with sugar at higher and lower levels.

If diet sodas propagate a sweet tooth, they may be the reason why you—without even realizing it, perhaps—tend to prefer particular sauces, spreads, dressings, breads, and crackers. You could unknowingly be adding back every day the calories and sugar you avoid at the vending machine in the form of "stealth" sugar hidden in foods you never even thought of as sweet.

The effect of sweeteners on taste preference may be why evidence that diet sodas actually help with weight control has been very elusive. There is some evidence of a benefit in the context of controlled trials, including a recent study of young children in the Netherlands. But overall, the evidence is murky at best.

In comparison to diet sodas, water isn't just a no-calorie drink; it's a no-sweetener drink as well. For those inclined to drink dairy, it's worth noting that all varieties of milk have calories, and thus, on a "calories only" scale, will look less good than diet soda.

There are a variety of good no- and low-calorie beverage options beyond plain water. Some seltzers come with fruit essence, offering some entertainment to our taste buds, but with no sugar, no calories, no sodium, and no sweetness. There are lightly sweetened tea beverages that provide some beneficial antioxidants at a very minimal cost in calories and sugar. Of note, these beverages are far less sweet than diet soda, but on a calories-only scale, will look worse rather than better.

Some have already made the argument that the ABA is making this move not to promote public health, but to avoid regulation. There is also an argument to be made that calories are the straw man, or scapegoat, of the soft drink world. By focusing all of the attention there, opportunity is created for other forms of mischief to fly under the radar.

We could, and in my opinion should, lower the radar accordingly. It is possible to capture overall nutritional quality in a single number that could fit anywhere a calorie count could fit. I know this, because I have devoted years to the development of just such a system, called NuVal. NuVal, and other nutritional profiling systems, reflect the sugar and calorie content of a drink or food, but also capture everything else important about its nutritional quality. In the case of NuVal, there is specific consideration of artificial sweeteners and sugar substitutes as well. The result is a measurement scale that actually correlates with health outcomes, and has been associated in real-world settings with weight loss, at times to a stunning degree. One of the many virtues of foods and drinks that are more nutritious overall is that they help us get to full, and stay there, on fewer calories over the course of any given day.

For our purposes today, the issue is simply that overall nutritional quality matters in ways well beyond calories. Eating or drinking less of any given junk food will lower calorie intake at a given time, but is unlikely to produce lasting fullness the way wholesome foods do. If you wind up hungry again soon, the calories you left out now simply make their way back in a little while. There is no lasting benefit.

Similarly, what we feed our taste buds shapes our taste preferences, and those, in turn, influence our food choices throughout the day. What happens at the vending machine may reverberate well beyond.

The alternative to awareness is obliviousness, or denial, and awareness is better. Awareness of calories is important because, unquestionably, they count. I have argued here before that, fundamentally, a calorie is a calorie, and ultimately, what we weigh relates directly to the total number of calories we consume, and combust—as does much about our health. Energy balance matters. So again, the ABA initiative is a good thing, as far as it goes.

But a calorie count is, quite simply, not a full accounting of what matters about a food, or beverage. Please chew on that, and choose accordingly.

Hungry for more? Write to eatandrun@usnews.com with your questions, concerns, and feedback.

David L. Katz, MD, MPH, FACPM, FACP, is a specialist in internal medicine and preventive medicine, with particular expertise in nutrition, weight management, and chronic-disease prevention. He is the founding director of Yale University's Prevention Research Center, and principal inventor of the NuVal nutrition guidance system. Katz was named editor-in-chief of Childhood Obesity in 2011, and is president-elect of the American College of Lifestyle Medicine.