Which foods are responsible for obesity – The role of proteins
A year-long study of the eating habits of 9,341 Australians concluded that highly processed foods are the main cause of rising obesity rates in the Western world.
The new study, conducted by the Charles Perkins Center (CPC) at the University of Sydney, was based on a national survey of diet and physical activity carried out by the Australian Bureau of Statistics (ABS).
The researchers relied on the Protein Leverage Hypothesis, first formulated in 2005 by Professors Raubenheimer and Stephen Simpson, which claims that people consume too much fat and carbohydrates because of the body’s strong desire for protein , which it prefers over other elements. Many modern diets consist of highly processed foods that are low in protein, causing people to consume higher calorie foods until they meet their protein needs.
Processed foods lack protein and cause cravings
Dr. Amanda Grech, the lead author and a postdoctoral researcher at the Charles Perkins Center and School of Life and Environmental Sciences, emphasized that as individuals consume more junk food or highly processed foods, their protein intake decreases, raising the likelihood of weight gain and obesity. This, in turn, heightens the risk of chronic diseases.
“It’s becoming increasingly clear that our bodies eat to meet a protein target,” added Professor David Raubenheimer, an expert in Nutritional Ecology. “But the problem is that the foods in Western diets contain less and less protein. Therefore, you need to consume more protein to reach your goal, which effectively increases your daily energy intake. Humans, like many other species, have a greater appetite for protein than for fat and carbohydrates. This means that if the protein in our diet is diluted with fats and carbohydrates, we will eat more to get the protein our bodies want .’
Proteins are the building blocks of life: they are contained in every cell of the body and are used to rebuild and create new cells. Protein can be obtained from various dietary sources, including meats, milk, fish, eggs, soy, legumes, and specific grains like wheat germ and quinoa.
Scientists at the University of Sydney analyzed data from a Diet and Physical Activity Survey of 9,341 adults, average age 46.3, conducted between May 2011 and June 2012. They found that the average energy intake of population was 8,671 kilojoules (kJ – energy unit), with the average percentage of energy from protein being just 18.4%, compared to 43.5% from carbohydrates, 30.9% from fat, just 2.2% from plant fiber and 4.3% from alcohol.
After adjusting for parameters, they found that those who consumed less protein at the first meal of the day continued to increase their total food intake at subsequent meals, while those who received the recommended amount of protein decreased their food intake throughout the day.
Starvation for protein leads to overeating
They also found a statistically significant difference between the groups by the third meal of the day: A higher proportion of energy from protein at the beginning of the day resulted in a much lower total energy intake throughout the day. Those who consumed low-protein foods at the beginning of the day increased food consumption to compensate for total energy intake . This was despite the fact that the first meal was the smallest for both groups, with the least amount of energy and food consumed, while the last meal was the largest.
Participants with a lower-than-recommended ratio of protein at the first meal consumed higher-calorie foods high in saturated fat, sugar, salt, or alcohol throughout the day and less of the five recommended food groups (grains, vegetables & legumes, fruit, dairy and meat). That is, they followed a diet poorer in nutritional value, with the percentage of protein energy decreasing, an effect scientists call “protein dilution” .
The study is important because it confirms that people are basically looking for protein in their diet, and as protein levels increase, they eat less fat and carbohydrates.
Although there are many factors involved in weight gain and obesity, scientists at the University of Sydney argue that the body’s strong desire for protein and its lack in overly processed foods are a key cause of overconsumption and obesity in the Western world.
The obesity explanation
Professor Raubenheimer underscores that research confirms the pivotal role of protein in the obesity epidemic, carrying substantial implications for global health.
Trying to understand the role of protein in the human diet, Professor Raubenheimer studied the diet of people in some of the most remote places, from the Congo to the Himalayas. “The protein mechanism in appetite is a revolutionary perspective,” he said. ” Obesity, diabetes, cardiovascular disease—it’s all due to diet, and we need to use what we’re learning to get it under control .”
The CPC team’s study was selected by the editors of Obesity as one of the top five publications of the year, and its leader, Professor Raubenheimer, was invited to speak at the annual Obesity Journal Symposium in San Diego on 4 November.