Alarmingly, about 14 million Australians are living with overweight or obesity according to the National Obesity Strategy 2022-2032. That’s 2 in every 3 adults, and 1 in 4 children.
The rise in obesity in the general population and the use of terms like ‘obesity epidemic’ makes it clear how much of an impact obesity has on health. We’ve also known that specific lifestyle factors strongly contribute to this rise in obesity, including our increasingly sedentary lifestyles and modern diets high in processed foods.
New research from the University of Sydney investigated the nutritional profile of such highly processed foods, to pose a more thorough explanation as to why and how they drive obesity so significantly.
The researchers drew from Australian Bureau of Statistics (ABS) data on the nutrition of the Australian population over the age of two from 2011 to 2012. From this data, they looked at the responses of more than 9,000 adults, to check their average energy intake and the proportion derived from protein, carbohydrates, fat, fibre and alcohol. They also considered the times people were eating (or drinking) and activity levels, as well as factors such as gender, BMI, educational status, age and country of birth. The data was analysed, with a focus on the proportion of energy intake derived from protein compared with other macronutrients.
The key findings were that people who ate adequate amounts of protein earlier in the day (and had a good balance of macronutrients) were likely to maintain this balance throughout the day and eat fewer calories overall. Those with lower protein consumption at the start of the day compensated for this by eating more protein in subsequent meals, but with an overall higher daily caloric intake, as they tended to consume more carbs and fats earlier in the day to make up for the lack of protein. This suggests that one of the drivers of higher caloric intake and obesity is not meeting a stable minimum adequate amount of protein until later in the day and eating more processed foods (high in carbohydrate and fat) to be sated.
Eating more fats and carbs to make up for a lack of protein is known as the ‘protein leverage hypothesis’. While highly processed and palatable food (junk or discretionary foods) tend to be energy-dense and low in protein, it seems that humans have a specific drive for protein which results in us eating a roughly set amount of protein during the day, regardless of how much energy we may have already consumed through junk food. Therefore, by ensuring adequate protein intake earlier in the day, we could help reduce overconsumption, in turn bringing down obesity.
