Processed foods leading cause of rising obesity, study finds

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A recent study showed that processed foods are a key contributor to the rising rates of obesity in the Western world.

The study, published in the journal, Obesity, was led by Amanda Grech, PhD, a postdoctoral research fellow at the University of Sydney Charles Perkins Centre (CPC) as well as the university’s School of Life and Environmental Sciences. For their investigation, Grech and her colleagues sought to better understand the relationship between consumption of processed food and increased hunger.

Researchers analyzed data from a cross-sectional Australian survey of nutrition and physical activity in 9,341 adults known as the National Nutrition and Physical Activity Survey. The survey was conducted between May 2011 and June 2012, and the mean age of respondents was 46.3.

Results showed that the population’s mean energy intake was 8,671 kilojoules (kJ). Findings also showed that participants' mean intake of energy from protein was only 18.4 percent while their carbohydrate intake accounted for 43.5 percent of their diet. In addition, their fat intake was 30.9 percent of their diet with their fiber intake at 2.2 percent of their diet, and alcohol at 4.3 percent.

Next, researchers plotted energy intake versus the time of consumption and found those who consumed lower amounts of protein in their first meal of the day went on to increase overall food intake in subsequent meals. In contrast, those who ate a protein focused breakfast declined their food intake throughout the day. Additionally, those who ate less protein at the start of the day continued to eat more foods high in saturated fats, sugars, salt, or alcohol and less grains, vegetables, fruits, dairy, and meats.  

According to the study’s author, these results indicate that processed foods, which typically are low in protein and high in carbohydrates, sugar, fat, and sodium drive increased eating because they do not satisfy one’s recommended protein intake.

"The results support an integrated ecological and mechanistic explanation for obesity, in which low-protein, highly processed foods lead to higher energy intake in response to a nutrient imbalance driven by a dominant appetite for protein," said researcher David Raubenheimer, PhD, the Leonard Ullmann Chair in Nutritional Ecology at the School of Life and Environmental Sciences. "It supports a central role for protein in the obesity epidemic, with significant implications for global health."