Americans have become significantly more obese over the past 25 years, primarily due to increased calorie intake rather than reduced calorie expenditure. This increase is linked to technological innovations in food preparation, which have made food easier and faster to prepare and consume. These innovations have reduced the time cost of food, leading to more frequent and varied food consumption. The paper argues that the rise in obesity is not due to reduced physical activity but rather to changes in food production and consumption patterns. The authors test their theory using data on food consumption, energy expenditure, and demographic factors. They find that increased caloric intake, particularly from snacks and mass-produced foods, is the main driver of the obesity increase. The paper also examines the role of self-control in food consumption, suggesting that lower time costs of food preparation may exacerbate overeating for individuals with self-control issues. The findings indicate that obesity rates are correlated with access to new food technologies and processed foods, and that regulatory environments in different countries influence obesity levels. The paper concludes that while lower food production costs can lead to welfare gains for most people, they may also contribute to obesity for those with self-control problems.Americans have become significantly more obese over the past 25 years, primarily due to increased calorie intake rather than reduced calorie expenditure. This increase is linked to technological innovations in food preparation, which have made food easier and faster to prepare and consume. These innovations have reduced the time cost of food, leading to more frequent and varied food consumption. The paper argues that the rise in obesity is not due to reduced physical activity but rather to changes in food production and consumption patterns. The authors test their theory using data on food consumption, energy expenditure, and demographic factors. They find that increased caloric intake, particularly from snacks and mass-produced foods, is the main driver of the obesity increase. The paper also examines the role of self-control in food consumption, suggesting that lower time costs of food preparation may exacerbate overeating for individuals with self-control issues. The findings indicate that obesity rates are correlated with access to new food technologies and processed foods, and that regulatory environments in different countries influence obesity levels. The paper concludes that while lower food production costs can lead to welfare gains for most people, they may also contribute to obesity for those with self-control problems.