Ultra-processed food linked to dilution of protein energy intake and overweight/obesity

New research presented at this year's International Congress on Obesity in Melbourne (the biennial congress of the World Obesity Federation) shows how increasing consumption of ultra-processed foods (UPFs) is associated with both dilution of protein consumption and increasing BMI and overweight/obesity.

The protein leverage hypothesis states that dietary protein dilution (meaning reduction of the proportion of energy contributed by protein in the diet) has contributed to the obesity epidemic. At the same time, in the past 20 years UPF consumption has risen from contributing 52% to 57% of total energy intake in the USA in adults.

Dividing the extent of consumption of UPF into five groups from the bottom 20% to the top 20% (quintiles) has been shown to be associated with increasing energy intakes and the dilution of energy provided by protein from 18.2% to 13.3%, even though absolute protein intake remains consistent across the five groups. This new study compared these different methods of assessing 'unhealthy' of foods with how they dilute protein energy intake, and their subsequent association with overweight / obesity.

The team used an approach called nutritional geometry, to detect complex nutritional associations in diets. It untangles the multi-dimensionality of diet as when one nutrient changes, other nutrients change as a consequence.

 The researchers also analysed mean body mass index (BMI) related to the changes, excluding low energy reporters (participants who had very low energy intakes and were excluded to improve the estimates). BMI increased as consumption of processed/discretionary foods increased.

A reduced proportion of energy from protein increases total energy intake because several studies, including randomised controlled trials have now found that people consume a fixed target of protein each day.