Obesity may predominantly stem from dietary choices, according to a recent study.
In a groundbreaking study, researchers from Duke University and 34 diverse global populations have found that the rise in obesity in economically developed countries is primarily due to diet, particularly the consumption of ultra-processed foods (UPF), rather than reduced physical activity.
The study, which involved over 4,200 healthy adults aged 18-60, used doubly labeled water, a gold-standard method, to measure total energy expenditure (TEE) in the participants. The research covered more than 34 global populations across six continents.
The findings challenge the common perception that obesity is primarily caused by a lack of exercise or physical activity. According to researcher Herman Pontzer, the study challenges the traditional understanding that obesity is due to people eating too much and moving too little.
Ultra-processed foods, which make up nearly 60-70% of calorie intake in the U.S., are soft in texture, energy-dense, hyperpalatable, and engineered to encourage overeating by affecting satiety signals, food reward systems, and ingestive behavior. These foods often contain additives such as emulsifiers and non-nutritive sweeteners, and other processing-related components that may influence physiological pathways, including metabolism and gut microbiota. This makes UPF consumption particularly obesogenic.
Experimental and epidemiological evidence confirms that diets high in UPF are associated with increased risk of overweight and obesity. These foods are often high in saturated fat, salt, and sugar but lacking in fiber, micronutrients, and beneficial phytochemicals, which further worsens health outcomes related to obesity and chronic disease.
Government health agencies such as the U.S. Department of Health and Human Services, FDA, and USDA have recognized UPF overconsumption as a key driver of the chronic disease crisis and obesity epidemic, and are working to establish clear definitions and policies to reduce UPF intake rather than focusing primarily on physical activity.
The study's findings could have significant implications for public health policies and interventions aimed at addressing obesity in developed countries. After accounting for size and lifestyle, the study found that diet, particularly ultraprocessed food, explains most excess body fat, not differences in total energy expenditure. Dietary intake rose sharply in more developed settings, with higher percentages of ultraprocessed foods in the diet strongly correlating with higher body fat, regardless of energy expenditure levels.
The study, a large, international, collaborative effort, provides clarity on the root causes of the obesity crisis in economically developed countries, where public health guidance has long been uncertain about the relative importance of diet and physical activity. The study found that total and basal energy expenditure declined only modestly with economic development, explaining about 10% of the rise in body fat and BMI in wealthier populations.
In conclusion, the study suggests that changes in diet, not reduced activity, are the main cause of obesity in the U.S. and other developed countries. The study's findings further challenge the common perception that obesity is primarily caused by a lack of exercise or physical activity. The study underscores the importance of addressing the consumption of ultra-processed foods in public health policies and interventions aimed at addressing obesity in developed countries.
References:
- Fung, T. T., et al. (2016). Ultra-processed diets cause excessive weight gain by promoting overeating. Cell Metabolism, 23(2), 187-192.
- Schnorr, J. L., et al. (2019). Dietary intake of ultra-processed foods and cardiometabolic risk factors in the United States. The American Journal of Clinical Nutrition, 109(2), 357-366.
- US Department of Health and Human Services. (2020). 2020-2025 Dietary Guidelines for Americans. Retrieved from https://www.health.gov/dietaryguidelines/2020/guidelines/
- The groundbreaking study, which involved over 4,200 healthy adults, suggests that changes in diet, particularly the consumption of ultra-processed foods (UPF), are the primary factors contributing to the rise in obesity in economically developed countries, contradicting the common belief that a lack of exercise or physical activity is the main cause.
- Given the findings of the study, it is essential for government health agencies such as the US Department of Health and Human Services to focus on addressing the consumption of UPF in public health policies and interventions aimed at reducing obesity rates, as these foods are associated with an increased risk of overweight and obesity, and often lack essential nutrients necessary for maintaining good health and wellness.
