Protein Valuation in Food Choice Is Positively Associated with Lean Mass in Older Adults

Charlotte M Buckley,Sophie Austin,Bernard M Corfe,Mark A Green,Alexandra M Johnstone,Emma J Stevenson,Elizabeth A Williams,Jeffrey M Brunstrom

doi:10.1093/jn/nxz124

Abstract

BackgroundCalorie for calorie, protein is more satiating than carbohydrate or fat. However, it remains unclear whether humans perceive calories derived from these macronutrients equally and whether lean mass is associated with a tendency to “value” protein when dietary decisions are made. ObjectiveThis study aimed to determine the test-retest reliability of a novel method for quantifying macronutrient valuations in human volunteers and to determine whether “protein valuation” is associated with a higher fat-free mass index (FFMI) in older adults. MethodsA 2-alternative, forced-choice task in which 25 foods were compared in 300 trials was undertaken in 2 studies. In study 1, participants (age range 19–71 y, n = 92) attended 2 test sessions, spaced 1 wk apart. In study 2, older adults (age range 40–85 y; n = 91) completed the food-choice task and assessed the test foods for liking, expected satiety, and perceived healthiness. Body composition and habitual protein intake were assessed in both studies. Data were analyzed through the use of individual binomial logistic regressions and multilevel binomial logistic regressions. ResultsIn study 1, measures of macronutrient valuation showed excellent test-retest reliability; responses in the forced-choice task were highly correlated (week 1 compared with week 2; protein, r = 0.83, P < 0.001; carbohydrate, r = 0.90, P < 0.001; fat, r = 0.90, P < 0.001). Calorie for calorie, protein and carbohydrate were stronger predictors of choice than fat (P < 0.001). In study 2, protein was a stronger predictor than both carbohydrate (P = 0.039) and fat (P = 0.003), and a positive interaction was observed between protein valuation and FFMI (OR = 1.64; 95% CI: 1.38, 1.95; P < 0.001). This was the case after controlling for age, gender, liking for foods, and habitual protein consumption. ConclusionTogether, these findings demonstrate that adult humans value calories derived from protein, carbohydrate, and fat differently, and that the tendency to value protein is associated with greater lean mass in older adults.

Highlights

Many modern foods are energy dense and the role this plays in promoting energy intake has been explored extensively [1]
Numerous studies have explored the relationship between food energy density, food intake, and food preference [28]
We introduce a novel method that quantifies the underlying value that humans place on a calorie derived from fat, carbohydrate, and protein

Summary

Introduction

Many modern foods are energy dense (kcal/g) and the role this plays in promoting energy intake has been explored extensively [1]. Humans do not detect energy-density directly and foods with equal energy density might differ in their fat, protein, and carbohydrate content, each of which is absorbed and utilized in different ways [2]. Intervention studies have demonstrated a causal association: muscle function is impaired when protein intake is reduced [8] and protein supplementation produces a corresponding improvement [9]. Calorie-for-calorie, protein is more satiating than carbohydrate or fat It remains unclear whether humans perceive calories derived from these macronutrients and whether lean mass is associated with a tendency to ‘value’ protein when dietary decisions are made

Methods

Results

Conclusion