Ultra-processed and refined foods, which make up a large part of the modern diet, are the main culprits of the obesity epidemic in the Western world, believe the authors of a study published in November 2022 in the journal obesity.
This study confirms the growing body of evidence supporting the “protein leverage” hypothesis.
This hypothesis, introduced in 2005 by David Raubenheimer and Stephen Simpson of the Charles Perkins Center at the University of Sydney, holds that when protein intake is below requirements, the body’s desire to reach its target intake in protein will continue to consume unnecessary calories until the need for protein is met. People overeat fats and carbohydrates due to the body’s strong appetite for protein, which it actively prioritizes over everything else.
Two predictions that flow from the hypothesis are that humans:
regulate food intake to keep protein within a narrow range;
energy (calorie) intake is an inverse function of the percentage of energy from protein because absolute protein intake is kept within narrow limits (when protein intake is low, calorie intake increases).
Food contains less and less protein
Being low in protein, ultra-processed and refined foods make you hungry and lead to more eating, the study confirms.
Foods in Western diets contain less and less protein. So you need to eat more of it to reach your protein goal, which effectively increases your daily energy (calorie) intake.says Raubenheimer, co-author of the new study.
The role of proteins
Proteins are the building blocks of life: every cell in the body contains them, and they are used to repair cells or make new ones; it is estimated that more than one million forms of protein are necessary for the functioning of the human body.
Sources of protein include meats, milk, fish, eggs, soy, legumes, beans, and some grains like wheat germ and quinoa.
‘Protein Hunger’ Is the Root of Overeating
University of Sydney researchers (1) analyzed data from a national survey conducted in 2011-2012 with 9,341 people representative of the population. The average age was 46.3 years. The average energy intake was 2072 calories per day, with the average percentage of energy from protein being only 18.4%, compared to 43.5% from carbohydrates and 30.9% from fat, and 2 .2% for fiber and 4.3% for alcohol. (QUICK CALCULATION of your calorie needs according to your basal metabolism and your activity)
Both predictions of the hypothesis were confirmed: mean protein intake was 18.4%, and energy (calorie) intake decreased with increasing energy from protein.
People with a higher proportion of energy from protein at the start of the day had a much lower total energy intake for the day.
Ultraprocessed discretionary foods have been shown to be a significant protein diluent and are associated with increased energy intake but not protein intake.
Participants with a lower than recommended proportion of protein at the first meal ate more discretionary foods (foods that were energy-dense and high in saturated fat, sugars, salt, or alcohol) throughout the day, and less than five recommended food groups (cereals, vegetables/legumes, fruits, dairy products and meats). As a result, their diet was worse overall at each meal, with their percentage of protein energy decreasing even as their consumption of discretionary foods increased – an effect scientists call “protein dilution”.
“These results support an integrated ecological and mechanistic explanation of obesity, in which highly processed low-protein foods lead to higher energy intake due to the biological response to macronutrient imbalance induced by a dominant appetite for protein.“, conclude the researchers. “This study supports a central role for protein in the obesity epidemic, with significant implications for global health.»
The CPC team study was chosen by Obesity editors as one of the top five papers of the year.
For more information on processed eating, the protein boost, and weight loss, see the links below.
(1) Amanda Grech, Zhixian Sui, Anna Rangan, Stephen J. Simpson, Sean C.P. Coogan, David Raubenheimer.
Psychomedia with sources: University of Sydney, Obesity.
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