Processed foods have never been favorites of nutritionists, and recent research now bolsters the claim that such foods are the leading cause of obesity in the Western world. It all comes down to something known as the Protein Leverage Hypothesis.
Developed by the University of Sydney's professors David Raubenheimer and Stephen Simpson, the hypothesis was initially put forward 18 years ago.
It begins with the concept that because the human body is naturally driven to seek out and consume protein, we tend to keep eating until our daily protein needs are met. Unfortunately, the processed and refined foods that make up much of the Western diet are typically low in protein. As a result, we end up eating large amounts of those foods – which are often rich in fats and carbohydrates – in order to satisfy our protein requirements.
For the new study, a U Sydney team led by Dr. Amanda Grech set out to see how much the Protein Leverage Hypothesis actually plays out in the real world. In order to do so, the scientists analyzed data from the National Nutrition and Physical Activity Survey, which documented nutrition and physical activity in 9,341 Australian adults between May 2011 and June 2012.
Among other things, it was found that when people ate a fairly low-protein breakfast, they tended to consume larger amounts of food in subsequent meals. This finding supports the hypothesis, as it suggests that the individuals were trying to meet their protein needs by eating more food throughout the day.
And likewise, it was also observed that when people ate a breakfast with more protein, their food intake was lower for subsequent meals. It should additionally be noted that as compared to their counterparts who had lower-protein breakfasts, people who had higher-protein breakfasts consumed fewer energy-dense foods high in saturated fats, sugar and salt later in the day.
"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 Prof. Raubenheimer. "It supports a central role for protein in the obesity epidemic, with significant implications for global health."
A paper on the research was recently published in the journal Obesity.
Source: University of Sydney
