Processed Foods Linked to Rising Obesity Rates, Study Shows.
A year-long study of the dietary habits of 9,341 Australians has confirmed that highly processed and refined foods are a leading contributor to the rise in obesity rates in the Western world. The study, based on a national nutrition and physical activity survey conducted by the Australian Bureau of Statistics (ABS), supports the ‘Protein Leverage Hypothesis‘, which suggests that people overeat fats and carbohydrates due to the body’s strong appetite for protein. As modern diets are low in protein and consist mainly of highly processed and refined foods, individuals are driven to consume energy-dense foods until they meet their protein demand. The research, conducted by the University of Sydney’s Charles Perkins Centre (CPC), was published in the latest issue of the journal Obesity.
Processed foods lacks protein, leading to overeating
According to Dr. Amanda Grech, a Postdoctoral Research Fellow at the Charles Perkins Centre (CPC) and the University of Sydney’s School of Life and Environmental Sciences, the consumption of junk foods or highly processed and refined foods leads to diluting dietary protein, thus increasing the risk of obesity and chronic diseases.
As Professor David Raubenheimer, the Leonard Ullmann Chair in Nutritional Ecology at the School of Life and Environmental Sciences, points out, Western diets are increasingly deficient in protein. Humans have a stronger appetite for protein than for fats and carbohydrates. Diluted protein in our diets leads to overeating and an elevated daily energy intake.
Protein is essential to good health, as every cell in the body contains proteins, and they are used to repair or make new cells. Meat, fish, milk, eggs, soy, legumes, beans, wheat germ, and quinoa are good sources of protein.
The University of Sydney researchers analyzed data from the National Nutrition and Physical Activity Survey, which included 9,341 adults with a mean age of 46.3 years. The study found that the population’s mean energy intake was 8,671 kilojoules (kJ), with just 18.4 percent of the energy from protein, compared with 43.5 percent from carbohydrates and 30.9 percent from fat. Fiber accounted for just 2.2 percent, while alcohol made up 4.3 percent.
The study also found that those who consumed lower amounts of protein in their first meal of the day consumed more food in subsequent meals, while those who received the recommended amount of protein did not.
Processed foods dilute protein, leading to overeating
According to Dr. Amanda Grech, a Postdoctoral Research Fellow at the Charles Perkins Centre (CPC) and the University of Sydney’s School of Life and Environmental Sciences, the consumption of junk foods or highly processed and refined foods leads to diluting dietary protein, thus increasing the risk of obesity and chronic diseases.
As Professor David Raubenheimer, the Leonard Ullmann Chair in Nutritional Ecology at the School of Life and Environmental Sciences, points out, Western diets are increasingly deficient in protein. Humans have a stronger appetite for protein than for fats and carbohydrates. Diluted protein in our diets leads to overeating and an elevated daily energy intake.
Protein is essential to good health, as every cell in the body contains proteins, and they are used to repair or make new cells. Meat, fish, milk, eggs, soy, legumes, beans, wheat germ, and quinoa are good sources of protein.
The University of Sydney researchers analyzed data from the National Nutrition and Physical Activity Survey, which included 9,341 adults with a mean age of 46.3 years. The study found that the population’s mean energy intake was 8,671 kilojoules (kJ), with just 18.4 percent of the energy from protein, compared with 43.5 percent from carbohydrates and 30.9 percent from fat. Fiber accounted for just 2.2 percent, while alcohol made up 4.3 percent.
The study also found that those who consumed lower amounts of protein in their first meal of the day consumed more food in subsequent meals, while those who received the recommended amount of protein did not.
Protein hunger driving overeating, study finds
A study by researchers at the Charles Perkins Centre, University of Sydney, has found that a lack of protein in Western diets is contributing to overeating, obesity and chronic diseases. The study analysed data from the National Nutrition and Physical Activity Survey and found that the mean percentage of energy from protein in the population’s diet was just 18.4%, compared with 43.5% from carbohydrates and 30.9% from fat. Participants who consumed less protein at the start of the day sought to compensate by increasing their overall energy intake throughout the day, leading to higher consumption of discretionary foods and poorer diet quality. The scientists call this phenomenon “protein dilution”.
The researchers also found that participants who received the recommended amount of protein at the start of the day did not increase their overall energy intake throughout the day. They consumed fewer discretionary foods and had a higher quality diet. This confirms the Protein Leverage Hypothesis, which suggests that humans have a stronger appetite for protein than for fats and carbohydrates. The scientists argue that the Western diet’s decreasing proportion of protein is a key driver of energy overconsumption and obesity in the Western world.
Explanation for obesity: Low protein, highly processed foods to blame
According to Professor Raubenheimer, the results of the study provide an explanation for obesity as it shows how low-protein, highly processed foods lead to overconsumption of energy due to a nutrient imbalance driven by the body’s appetite for protein. This supports the idea that protein plays a central role in the obesity epidemic, which has significant implications for global health.
Studying human nutrition has taken Professor Raubenheimer to some of the world’s most remote places, from the Congo to the Himalayas, in an effort to understand how protein drives our appetites. He believes that this revolutionary insight can help us bring obesity, diabetes, and cardiovascular disease under control, as these health conditions are all driven by our diet.
Abstract
Objective
The protein leverage hypothesis (PLH) postulates that strong regulation of protein intake drives energy overconsumption and obesity when human diets are diluted by fat and carbohydrates. The two predictions of the PLH are that humans (i) regulate intake to maintain protein within a narrow range and that (ii) energy intake is an inverse function of percentage energy from protein because absolute protein intake is maintained within narrow limits.
Methods
Multidimensional nutritional geometry was used to test the predictions of the PLH using dietary data from the Australian National Nutrition and Physical Activity Survey.
Results
Both predictions of the PLH were confirmed in a population setting: the mean protein intake was 18.4%, and energy intake decreased with increasing energy from protein (L = −0.18, p < 0.0001). It was demonstrated that highly processed discretionary foods are a significant diluent of protein and associated with increased energy but not increased protein intake.
Conclusions
These results support an integrated ecological and mechanistic explanation for obesity, in which low-protein highly processed foods lead to higher energy intake because of the biological response to macronutrient imbalance driven by a dominant appetite for protein. This study supports a central role for protein in the obesity epidemic, with significant implications for global health.