The Lunch Study: the Combined Effects of Food Texture and Portion Size on Intake

The Lunch Study: the Combined Effects of Food Texture and Portion Size on Intake

Meal size is strongly influenced by a number of external features of the food environment which can promote over-consumption, such as the availability of palatable energy dense foods and large portion sizes. The current research aimed to investigate whether natural food-based differences in texture could be used to slow down eating rate and reduce intake from large portions.

A four-session randomised crossover study assessed the effect of faster vs. slower eating rate, achieved through manipulating food texture, on ad-libitum consumption (weight and calories) of a meal, alone and in combination with variations in meal portion size (regular vs. large)

The current obesogenic environment is characterized by the abundance of palatable and high energy dense foods. Eating from large portions can promote sustained overcompensation at meal times. On the other hand, eating at a slower rate has been shown to reduce meal size, and food-based texture differences can slow eating rate. It is possible that texture-based differences in eating rate could be used to reduce energy intake in of foods that are served in large portions.

This study was conducted to quantify the effect of eating rate (fast vs. slow) on ad-libitum consumption of a meal, alone and in combination with variations in portion size (100 % 700 g vs 150 % 1050 g). The meal combinations were as follows:

Meal 1: thin/100% portion; Meal 2: thin/150% portion; Meal 3: thick/100% portion; Meal 4: thick /150% portion

Participants consumed the four test meals over four non-consecutive test sessions at the Clinical Nutrition Research Centre, with at least three days washout between each session. Each part followed a completely randomised full crossover design.

The primary objective was to assess ad libitum intake (both kcal and g) of the test meals, depending on the combination of food texture and energy density.

The secondary objectives were to assess the eating rate, oral processing characteristics, changes in rated appetite up to 90 minutes post-consumption and energy intake (kcal) for the rest of the test day (food diary), as a function of the test meal texture and energy density

Inclusion criteria:

• Aged between 21 and 50 years
• BMI < 30 kg/m2

Exclusion criteria:

• Individuals whose body weight has changed more than 5 kilograms in the last 12 months
• People who are taking insulin or medications known to affect glucose metabolism, appetite or energy metabolism
• Individuals who are currently dieting
• People with intolerances or allergies to study foods or test products, e.g. soya, wheat, gluten, cereal, fruits, biscuits, dairy products, rice, vegetable, meat, seafood, sugar and sweetener, gelatin, natural food colourings or flavourings, etc
• Pregnant women