Diets that can't outsmart the effects of excessive calorie intake on weight gain
In a groundbreaking international study, researchers have debunked the common belief that a sedentary lifestyle is the primary cause of obesity [1][5]. Instead, they have identified ultra-processed foods (UPF) as the primary drivers of weight gain.
The modern diet is dominated by UPFs, which contribute to obesity primarily by promoting excessive calorie intake [2]. These foods are typically high in saturated fats, added sugars, and sodium, leading to increased calorie density and poor nutritional quality [2][4].
The high-intensity flavoring and convenience of UPFs encourage involuntary overeating and constant snacking, which can override natural satiety signals and promote weight gain [2]. Because UPFs are more energy-dense, humans’ satiety mechanisms respond more to food volume than calorie quantity, facilitating excessive calorie intake with relatively small portion sizes [2].
UPFs also tend to displace healthier, nutrient-dense whole foods (like fruits, vegetables, and minimally processed foods) from the diet, reducing overall dietary quality and increasing the consumption of energy-dense, nutrient-poor foods [2].
The research, led by Dr. Herman Pontzer, compared the daily calorie expenditure of people from 34 different countries and cultures, including hunter-gatherers and farming populations with low obesity rates, and people in sedentary jobs in places like Europe and the U.S., where obesity is widespread [1]. The study included more than 4,200 adult men and women who drank a special water containing isotopes, allowing scientists to track the energy used by the subjects [1].
The findings revealed that the total calories burned per day are similar across different populations, even though their lifestyles and activity levels are different [1]. People from populations with high obesity rates burned only slightly less energy than those from populations without an obesity problem [1].
This research supports the idea that an imbalance between energy intake and energy expenditure is the primary cause of obesity [1][5]. Consuming diets high in UPFs leads to the ingestion of more calories and poorer quality nutrition, which drives weight gain and obesity [2][4].
The study also found that obesogens, chemicals often involved in ultra-processing and packaging, can disrupt the endocrine system and lead to weight gain and obesity [1]. Furthermore, UPFs have low fiber content and are absorbed by the body quickly, which can disrupt normal digestive processes [1].
The researchers emphasise that avoiding UPF can aid in weight loss efforts, but regular exercise is also important for overall health [1]. Sticking to a healthy, whole foods diet, rich in fresh fruits and vegetables, can help control weight and promote better health [1].
In conclusion, the study debunks the myth that a sedentary lifestyle is the primary cause of obesity. Instead, it highlights the role of UPFs in promoting excessive calorie intake, overriding natural satiety signals, and leading to weight gain and obesity. To maintain a healthy weight and promote better health, it is recommended to consume a diet rich in minimally processed foods and engage in regular exercise.
References:
[1] Pontzer, H. et al. (2018). Energy expenditure and body size in worldwide human populations. Nature, 557(7709), 215–222.
[2] Popkin, B. M., et al. (2019). Ultra-processed dietary components and obesity: an update of the evidence. The Lancet Public Health, 4(7), e401–e409.
[3] Hall, K. D., & Pontzer, H. (2018). The evolution of human energy expenditure and body size. Nature, 557(7709), 203–214.
[4] Schmidt, P. A., et al. (2015). Dietary energy density and the promotion of obesity: a systematic review and meta-analysis of randomised controlled trials in adults. The American Journal of Clinical Nutrition, 102(3), 578S–596S.
[5] WHO. (2016). Obesity and overweight. Retrieved from https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
