Sex differences in snack food reinforcement in response to increasing dietary protein

Authors: Casperson, Shanon; JOHNSON, LUANN - University Of North Dakota; Roemmich, James

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2016
Publication Date: 4/1/2017
Citation: Casperson, S.L., Johnson, L., Roemmich, J.N. 2017. Sex differences in snack food reinforcement in response to increasing dietary protein [abstract]. Federation of American Societies for Experimental Biology Conference. 31:652.15.

Interpretive Summary:

Technical Abstract: BRACKGROUND: Protein is posited to play a dynamic role in energy balance and reward-driven eating behavior. However, little is known about the effect of increasing protein intake on snack food reinforcement. OBJECTIVE: We sought to determine the extent to which increasing dietary protein changes the reinforcing value of snack foods in males and females. METHODS: In a randomized crossover study, 11 females (age = 25 ± 7y; BMI = 21 ± 2kg/m2) and 10 males (age = 22 ± 2y; BMI = 24 ± 2kg/m2) consumed a standard (15%) and high (30%) protein meal. Study visits were separated by at least one week and menstruating females were studied during the luteal phase (Days 15 - 20). Food reinforcement was assessed using a computer-based choice task (operant responding with concurrent log2(x) reinforcement schedules) 4h post-meal. Operant responding was ln-transformed prior to analysis to reduce skewness. Highly-palatable, energy-dense sweet and savory foods, which are most often chosen as snacks, were used to assess food reinforcement. Hedonic (liking) ratings for snack foods used to assess food reinforcement were measured prior to the start of the study via a 10-point visual analog scale. RESULTS: Hedonic ratings did not differ between the sexes for the snack foods. Snack food reinforcement was significantly greater in the males than females (p = 0.0477) and sweet snack foods were more reinforcing than savory snack foods (p = 0.0198). There were sex by dietary protein amount (p = 0.0348) and sex by snack food type (p < 0.0001) interactions for snack food reinforcement. Increasing dietary protein reduced food reinforcement, predominantly for the savory snack foods, in the females. Interestingly, food reinforcement in the males was not influenced by dietary protein or snack type. In addition, the reinforcing value of sweet foods did not differ between the sexes and was not influenced by changes in dietary protein. CONCLUSION: These preliminary results show that increasing dietary protein influences food reinforcement differently in males and females. Understanding the differential effects of meal macronutrient composition on the reinforcing value of foods will provide important insight into psychophysiological mechanisms of snacking behavior.