Effects of dietary protein and fiber at breakfast on postprandial appetite, neural responses to visual food stimuli, and ad libitum energy intake at lunch in overweight adults

Increasing either protein or fiber at mealtimes has relatively modest effects on satiety and ingestive behavior. Whether increasing protein and fiber in the same meal has additive or interactive effects on ingestive behavior is not known. Five female and 10 male overweight (BMI: 27.1 ± 0.2 kg/m 2 ) young adults (26 ± 1 y) were provided with breakfast meals of varying protein and fiber amounts (normal protein [12.5 g] + normal fiber [3 g], normal protein [12.5 g] + high fiber [8 g], high protein [25 g] + normal fiber [3 g], high protein [25 g] + high fiber [8 g]) during 4, 2‐week interventions in a randomized crossover manner. At the end of each intervention, fasting and postprandial appetite ratings, neural responses to visual food stimuli, and ad libitum energy intake at lunch were collected. A priori reward‐related brain regions of interest included bilateral insula, amygdala, orbitofrontal cortex, caudate, and putamen. Fiber intake at breakfast did not affect ingestive behavior outcomes. Higher protein intake at breakfast transiently decreased desire to eat 60 minutes after breakfast, but did not influence hunger, fullness, or energy intake at lunch. Compared to fasting‐state, right insula responses to visual food stimuli were decreased 180 min after consuming normal protein, but not high protein, breakfasts. In conclusion, these data do not support increasing dietary protein and fiber at breakfast as effective strategies for modulating neural reward processing and ingestive behavior in overweight adults. Support or Funding Information American Egg Board, NIH UL1 TR001108, USDA‐NIFA 2011‐38420‐20038, Purdue University Ingestive Behavior Research Center