Sugar Taxes to Combat Obesity: When Regulation Meets a Complex Health Problem

Obesity is no longer merely a matter of individual lifestyle, but one of the major public health challenges facing Western societies. This is particularly evident in the United Kingdom: In England, approximately 64.5% of adults were overweight or obese in 2023/24; 26.5% were obese. The problem also begins early in children: As many as 9.6% of four- to five-year-olds and 22.1% of ten- to eleven-year-olds were obese during the 2023–24 school year. The social dimension is significant: Children from the most disadvantaged regions are more than twice as likely to be obese as children from the least disadvantaged regions.

The health consequences extend far beyond body weight. Among other things, obesity increases the risk of type 2 diabetes, cardiovascular disease, and certain types of cancer. According to current estimates, nearly six million people in the United Kingdom now live with diabetes; about 90% of diagnosed cases are type 2 diabetes. The social and economic burden is correspondingly significant: the treatment of obesity and related conditions alone costs the NHS an estimated £6.5 billion per year. The broader economic costs of overweight and obesity are now estimated to be significantly higher.

In light of this trend, the question of its causes—and thus also of responsibility—inevitably arises. In the health policy debate, the food and beverage industry has increasingly come under scrutiny. At first glance, the argument seems plausible: The industry shapes a significant portion of the food environment, determines recipes, portion sizes, and product offerings, and thus directly influences the availability and composition of the food consumed. At the same time, the sector is of considerable economic importance. The British food and beverage industry is the country’s largest industrial production sector. Food and beverage production now generates approximately £37 billion in gross value added, generates revenue of nearly £148 billion, and directly employs nearly 500,000 people; more than four million jobs are supported along the entire food value chain.

Against this backdrop, regulating products with high sugar content appears to be a politically attractive approach: It does not directly address individual behavior, but rather changes the economic incentives for manufacturers. The United Kingdom followed precisely this principle with the Soft Drinks Industry Levy, which was announced in 2016 and introduced in April 2018. The so-called “sugar tax” was explicitly not designed as a traditional excise tax. Rather, a tiered levy was intended to encourage manufacturers and importers to reformulate sugary beverages, reduce portion sizes, and steer consumers toward lower-sugar alternatives.

The choice of the beverage industry was by no means random. As early as 2016, the British government argued that sugar-sweetened beverages were a significant source of free sugar, particularly among children and adolescents, and could at the same time be reformulated with relative ease. At that time, a single 330-ml can of a sugary soft drink could already contain around 35 g of sugar. The political logic was therefore strikingly simple: if the sugar content of these products could be reduced without requiring consumers to fundamentally change their behavior, regulation could have a broad impact on the population.

The British Soft Drinks Industry Levy was thus a remarkable experiment in public health policy. And indeed, the now extensive scientific literature shows a clear effect on the products themselves: the sugar content of soft drinks has been significantly reduced. But this raises the crucial question: Does less sugar in beverages actually translate to lower rates of obesity, fewer cases of diabetes, and better health outcomes in the population?

This is precisely where the actual scientific debate begins. For there are several causal intermediate steps between a change in product formulation, altered consumption behavior, and a measurable clinical benefit. While the effects of the UK levy on product composition are comparatively well documented, the question of its actual impact on body weight, obesity, and long-term morbidity is much more difficult to answer. The British experience thus offers not only an example of successful regulation—but also an opportunity to examine how a measurable regulatory success might be prematurely interpreted as a public health success.