Limitations.
obesity, weight loss
OBESITY
While our interpretation of increased tonic dopamine is supported by relative pharmacokinetic properties of D1/5 and D2-like receptors, and literature on D2-like receptor PET occupancy and fMRI activity, we did not directly measure brain dopamine. Consumption of dietary fat elicits rapid dopaminergic response in reward regions (Ad libitum eating behavior subsequent to the 5-day period of dietary restriction supports our interpretation of increased incentive salience for rewarding foods after the RF diet. However, our study was not specifically powered to detect differences in this exploratory outcome, and analyses were not corrected for multiple comparisons.Our interpretation of the effect of RC and RF diets on brain dopamine is limited to the early stages of initiating reduced-energy diets and does not address long-term changes or adaptations in neurochemistry or reward. Future studies should investigate changes in neurochemistry and reward activity in relation to diet composition over longer periods of weight loss. Furthermore, only adults with obesity were included in the present study. Adults without obesity appear to have a greater capacity to synthesize dopamine (Finally, the number of participants completing neuroimaging scans is relatively small. While we endeavored to collect data on 20 participants based on our prespecified power calculations, analyses ultimately were limited to 