June 2, 2025

expert reaction to unpublished conference abstract suggesting eating rate has sustained effects on energy intake from Ultra-Processed Diets

A conference abstract presented at NUTRITION 2025 looks at eating rate and its effects on energy intake from Ultra-Processed Diets. 

Dr Amanda Avery, Associate Professor in Nutrition and Dietetics, University of Nottingham, said:

“This very well considered study explores whether eating rate can make a difference to the amount of food we eat. Previous research has suggested that a 20% difference in eating rate leads to a 9-15% difference in food intake.

“In this study, the abstract being showcased at the American Nutrition conference,  the researchers used two different diets using commercially prepared ultra processed foods (UPFs). One diet used UPFs with textures that meant that eating rate was slower whilst the second diet used UPFs with textures leading to faster eating rates.

“Healthy young adults, both males and females with healthy body weights were invited to take part in the study where they were then randomised to be in one ‘block’ or the second block for assignment to the diet. They were not aware which diet they were consuming when – they had one diet for two weeks, then had a two week ‘rest’ and then had the second diet for two weeks. This means that we can compare the results between individuals besides between the two groups.

“The participants were offered as much food as they wanted when on either of the two diets. Incredibly, but perhaps not surprisingly, the findings on energy intake were consistent – all participants consumed less energy from food when on the two week UPF – slow eating rate diet. The average energy intake was 369kcal/day less when people were following the slow eating rate diet.

“Whilst there were no significant differences in body weight, this is not surprising given that the study was only being conducted for a two-week period and because participants were switched from one diet to another. However if a person was choosing a diet which led to an extra 350+kcal being consumed each day, then one could expect to see associated increases in body weight over time. 

“As mentioned, the study was well conducted with many reasons as to why participants may not be able to take part in the study. The researchers were keen to exclude anyone who had strict control over their food intake and also those people who were intentionally trying to reduce their body weight – thus other factors that may have contributed to the findings were limited in the study design.

“In terms of what this study adds – the study really reinforces the importance of people sitting down and taking time to enjoy their food. Eating foods quickly and ‘on the hoof’ may lead to extra energy intake which may long-term lead to weight gain. Ideally, we should be choosing foods with more texture, such as ultra-processed foods with more texture, but also balanced with vegetables, whole fruits, wholegrain cereals, beans, legumes, lean meat, fish, so that we have to chew the food. As this study has found, food with very little texture, such as certain UPFs, may lead to excess energy intake which over time may increase the risk of obesity, as demonstrated by other studies that have compared the intake of ultra processed with more minimally processed foods.”

Professor Julian Hamilton-Shield, Professor in Diabetes and Metabolic Endocrinology, University of Bristol, said:

“This study reinforces previous epidemiological, experimental and clinical trial data demonstrating that any manoeuvre to slow eating rate consistently, in this current study by meal texture, reduces an individual’s total calorie intake. Whilst it can be difficult to sustain a reduced eating speed, altering food texture that slows eating speed seems an attractive additional tool for population-based, weight management strategies.”  

The abstract ‘Eating Rate has Sustained Effects on Energy Intake from Ultra-Processed Diets: A Two-Week Ad Libitum Dietary Randomized Controlled Trial’ by Ciarán G. Forde et al. was presented at the NUTRITION 2025 conference, and the embargo lifted at 19:00 UK time Monday 2 June 2025.

Declared interests

Professor Julian Hamilton-Shield: I have conducted experimental and trial studies on slowing eating speed by different methodology, finding results for calorie intake in agreement with the study being described

Dr Amanda Avery: besides my academic position, I also hold a very part-time position as Consultant dietitian in Nutrition, Research & Health Policy at Slimming World.