A year-long study of the dietary habits of 9,341 Australians has backed growing evidence that highly processed and refined foods are the leading contributor of rising obesity rates in the Western world.
The new study [wiley.com], in the latest issue of the journal Obesity conducted by the University of Sydney's Charles Perkins Centre [sydney.edu.au] (CPC), was based on a national nutrition and physical activity survey undertaken by the Australian Bureau of Statistics (ABS), and further backs the 'Protein Leverage Hypothesis'.
First put forward in 2005 [doi.org] by professors Raubenheimer and Stephen Simpson, the Protein Leverage Hypothesis argues that people overeat fats and carbohydrates because of the body's strong appetite for protein, which the body actively favours over everything else. Because so much of modern diets consist of highly processed and refined foods – which are low in protein – people are driven to consume more energy-dense foods until they satisfy their protein demand.
[...] "It's increasingly clear that our bodies eat to satisfy a protein target," added Professor David Raubenheimer, the Leonard Ullmann Chair in Nutritional Ecology at the School of Life and Environmental Sciences.
"But the problem is that the food in Western diets contains increasingly less protein. So, you have to consume more of it to reach your protein target, which effectively elevates your daily energy intake.
[...] Participants with a lower proportion of protein than recommended at the first meal consumed more discretionary foods – energy-dense foods high in saturated fats, sugars, salt, or alcohol – throughout the day, and less of the recommended five food groups (grains; vegetables/legumes; fruit; dairy and meats). Consequently, they had an overall poorer diet at each mealtime, with their percentage of protein energy decreasing even as their discretionary food intake rose – an effect the scientists call 'protein dilution'.
Amanda Grech, Zhixian Sui, Anna Rangan, et al., Macronutrient (im)balance drives energy intake in anobesogenic food environment: An ecological analysis [open], Obesity, 30, 11, 2022. DOI: 10.1002/oby.23578 [doi.org]