Protein status and food reward.

Rationale:

Protein is an indispensable component within the human diet. It has been posed that protein intake is tightly regulated in the human body. In a previous study we showed that following a protein deficit, food intake and food preferences changed to restore adequate protein status.



Objective:

The primary objective of this study is to assess the effect of a low protein status on reward response when exposed to sight and smell of food stimuli high and low in protein compared with a high protein status.



Study design:

The study will consist of a 16-day fully controlled dietary intervention that will involve consumption of individualized, isoenergetic menus providing either 0.5 g protein/kg BW/day (low protein diet), or 2.0 g protein/kg BW/day (high protein diet), using a randomized crossover design. The diets will be followed by a 1-day ad libitum-phase, where protein (g) and energy (kJ) intake will be measured. Changes of reward responses in the brain will be measured by using functional magnetic resonance imaging (fMRI) when exposed to sight and smell of high and low protein food stimuli. Food preference will be measured by subjective ratings.



Study population:

The study population will consist of 24 apparently healthy, unrestrained female volunteers between the age of 18 and 35 with a normal weight.



Main study parameters/endpoints:

Our main outcome measurement is the change in brain reward response to sight and smell of high and low protein food stimuli after the low protein and high protein diets.

The protein status of an individual effects food preferences and intake. If the protein status is low, products high in protein will elicit greater reward.

Every participant will visit the laboratory every day during the intervention periods.

Two 16-day fully controlled intervention periods differing in dietary protein intake. These interventions involve consumption of individualized, iso-energetic menus providing either 0.5 g protein/kg bodyweight/day (low protein diet) or 2.0 g protein/kg bodyweight/day (high protein diet).