The industry responded with a national advertising campaign based on what it believed to be solid science. The ads explained that there was no such thing as a “fattening food”: “All foods supply calories and there is no difference between the calories that come from sugar or steak or grapefruit or ice cream.”
More than 60 years later, the sugar industry is still making the same argument, or at least paying researchers to do it for them. The stakes have changed, however, with a near tripling of the prevalence of obesity in the intervening decades and what the Centers for Disease Control and Prevention figures reveal to be an almost unimaginable 655 percent increase in the percentage of Americans with diabetes diagnoses. When it comes to weight gain, the sugar industry and purveyors of sugary beverages still insist, a calorie is a calorie, regardless of its source, so guidelines that single out sugar as a dietary evil are not evidence-based.
Surprisingly, the scientific consensus is technically in agreement. It holds that obesity is caused “by a lack of energy balance,” as the National Institutes of Health website explains — in other words, by our taking in more calories than we expend. Hence, the primary, if not the only, way that foods can influence our body weight is through their caloric content.
Another way to say this is that what we eat doesn’t matter; it’s only how much — just as the sugar industry would have us believe. A 2014 article in an American Diabetes Association journal phrased the situation this way: “There is no clear or convincing evidence that any dietary or added sugar has a unique or detrimental impact relative to any other source of calories on the development of obesity or diabetes.”
The absence of evidence, though, as the saying goes, is not necessarily evidence of absence. If the research community had been doing its job and not assuming since the 1920s that a calorie is a calorie, perhaps we would have found such evidence long ago.
The assumption ignores decades of medical science, including much of what has become textbook endocrinology (the science of hormones and hormone-related diseases) and biochemistry. By the 1960s, researchers in these fields had clearly demonstrated that different carbohydrates, like glucose and fructose, are metabolized differently, leading to different hormonal and physiological responses, and that fat accumulation and metabolism were influenced profoundly by these hormones. The unique composition of sugar — half glucose, half fructose — made it a suspect of particular interest even then.
The takeaway is that we should expect the consumption of different macronutrients to have differential effects on the hormonal milieu of our cells and so, among myriad other things, on how much fat we accumulate. These effects may be very subtle, but subtle effects can accumulate over a few years or decades into the anything-but-subtle phenomena of obesity and diabetes. In light of this research, arguing today that your body fat responds to everything you eat the exact same way is almost inconceivably naïve.
But don’t blame the sugar industry for perpetuating this view. Blame the researchers and the nutrition authorities.
The industry is in a perverse position: defending the core beliefs of nutrition and obesity research while simultaneously being accused by some of the prominent experts in these disciplines of following the tobacco-industry playbook and so acting as “merchants of doubt.” If this sounds like cognitive dissonance — well, it is.
I am a fierce critic of sugar and believe that it, in fact, may have prematurely killed more people than tobacco. The disorders for which it is the prime suspect — obesity and Type 2 diabetes — in turn elevate our risk of virtually every major chronic disease, from heart disease to cancer and Alzheimer’s. And yet on this issue, I think the sugar industry has a fair point in rejecting the comparison.
Cigarette companies are notorious for having worked to undermine the scientific consensus on tobacco, which was backed by compelling evidence. Tobacco executives knew as well as public health officials that nicotine was addictive and that smoking caused lung cancer. But the evidence implicating sugar as a unique cause of chronic disease has never been nearly so convincing. More to the point, the consensus among nutrition and obesity authorities has been completely aligned with sugar industry interests: Sugar advertisers have had to remind people only that what nutrition authorities believe to be true of all foods is therefore true of sugar as well.
So can we really blame sugar companies for seeking to rebut the contention of some nutrition researchers — that sugar might be a unique cause of diabetes and heart disease — by commissioning other mainstream nutritionists to make the opposite case? In the 1970s, when the industry paid Fred Stare, founder of the nutrition department at the Harvard School of Public Health, to exonerate sugar in a lengthy journal supplement, “Sugar in the Diet of Man,” all Mr. Stare had to do was enlist as authors some of the very influential researchers who were convinced that dietary fat was the real enemy (the conventional wisdom of the time that has now been largely overturned). No confusion needed to be sown. Their task was simply to reinforce the consensus.
“The method of science,” as the philosopher of science Karl Popper once put it, “is the method of bold conjectures and ingenious and severe attempts to refute them.” In nutrition, the conjectures (their boldness is debatable) are that obesity is caused by lack of energy balance, and so a calorie is a calorie. But they have been accepted with such faith that attempts to refute them have been anything but ingenious and severe. That the attempts have failed may speak more to the quality of the science than the validity of the conjectures. To fully understand the dangers of consuming sugar, we need experiments, in humans, that can unambiguously test these 100-year-old conjectures. No matter how time consuming or expensive these studies are.
To the sugar industry, the nutritionists’ dogmatic belief that obesity is a calorie overconsumption problem and a calorie is a calorie has been the gift that keeps on giving. So long as nutrition and obesity authorities insist that this is true, then the sugar industry can rightfully defend its product on the basis that the calories from sugar are no better nor worse than those from steak or grapefruit or ice cream — perhaps even kale or quinoa. We can’t have it both ways.