Research Article: The Impact of U.S. Free Trade Agreements on Calorie Availability and Obesity: A Natural Experiment in Canada

Date Published: May 1, 2018

Publisher: Elsevier Science

Author(s): Pepita Barlow, Martin McKee, David Stuckler.


Globalization via free trade and investment agreements is often implicated in the obesity pandemic. Concerns center on how free trade and investment agreements increase population exposure to unhealthy, high-calorie diets, but existing studies preclude causal conclusions. Few studies of free trade and investment agreements and diets isolated their impact from confounding changes, and none examined any effect on caloric intake, despite its critical role in the etiology of obesity. This study addresses these limitations by analyzing a unique natural experiment arising from the exceptional circumstances surrounding the implementation of the 1989 Canada–U.S. Free Trade Agreement.

Data from the UN (2017) were analyzed using fixed-effects regression models and the synthetic control method to estimate the impact of the Canada–U.S. Free Trade Agreement on calorie availability in Canada, 1978–2006, and coinciding increases in U.S. exports and investment in Canada’s food and beverage sector. The impact of changes to calorie availability on body weights was then modeled.

Calorie availability increased by ≅170 kilocalories per capita per day in Canada after the Canada–U.S. Free Trade Agreement. There was a coinciding rise in U.S. trade and investment in the Canadian food and beverage sector. This rise in calorie availability is estimated to account for an average weight gain of between 1.8 kg and 12.2 kg in the Canadian population, depending on sex and physical activity levels.

The Canada–U.S. Free Trade Agreement was associated with a substantial rise in calorie availability in Canada. U.S. free trade and investment agreements can contribute to rising obesity and related diseases by pushing up caloric intake.

Partial Text

The escalating global prevalence of overweight and obesity, or “globesity,” is often described as a pandemic.1 Worldwide, it is estimated that rates of overweight and obesity combined rose by 27.5% for adults and 47.1% for children between 1980 and 2013.2 Globalization via free trade agreements (FTAs) is often implicated in this pandemic because of its role in spreading high-calorie diets rich in salt, sugar, and fat.3 These concerns have become increasingly prominent in recent years, as new FTAs have been negotiated at an unprecedented rate, rising from 22 active FTAs in 1990 to more than 270 in 2016.4 They include the Transatlantic Trade and Investment Partnership, a potential agreement between the U.S. and the European Union, and a possible United Kingdom–U.S. deal.5 Public health specialists have argued that new FTAs could worsen diets and exacerbate rising rates of obesity.3

Figure 1 plots normalized trends in calorie availability in Canada and comparison countries and shows that the availability of calories increased markedly in Canada after CUSFTA. In Canada, calorie availability rose from 3,028.5 kcal/capita/day in 1988 just before CUSFTA was implemented to 3,491.0 kcal/capita/day in 2006. Thus, calorie availability was on average 343.1 (95% CI=294.3, 391.9) kcal/capita/day higher in Canada after CUSFTA compared with before CUSFTA. Since 1994, the rise in calorie availability in Canada far exceeded other countries, where calorie availability was on average 150.8 (95% CI=114.4, 187.1) kcal/capita/day higher post-CUSFTA following a period of weak economic performance in the late 1980s and early 1990s.33

This analysis suggests that calorie availability in Canada increased by approximately 170 kcal/capita/day after CUSFTA. This coincided with a US$1.82 billion (95% CI=US$1.18, US$2.46 billion) increase in U.S. investment in the Canadian food and beverage industry and a US$5.26 billion (95% CI=US$4.89, US$5.62 billion) rise in food and beverage imports from the U.S. The rise in caloric availability was estimated to lead to an average weight gain of 1.8–9.3 kg for men and 2.0–12.2 kg for women who were aged 40 years, depending on their physical activity levels and assumed pass-through from availability to intake. These results were robust across different model and sample specifications.

Notwithstanding its limitations, this study has important implications for policy. Public health scholars have long argued that dietary choices and obesity are influenced by food environments, which are, in turn, shaped by macrostructural factors.43, 44 This analysis suggests that FTAs can lead to a substantial rise in calorie availability and likely intake, which plays a critical role in the development of obesity. Thus, this study shows empirically how trade policy is a macrostructural driver of dietary behaviors.44 This paper also strengthens the legitimacy of growing concerns raised during FTA negotiations about the potentially detrimental impacts of U.S. FTAs and the need for greater coherence between nutrition and trade policy making.5, 45




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