In this study, we investigated the effects of dietary restriction (DR) and variable diets on phenotypes and gene expression in oriental fruit fly, Bactrocera dorsalis (Hendel), one of the most economically important pests in the family Tephritidae around the world. As expected, we found that DR altered the B. dorsalis phenotypes by significantly increasing stress resistance and lifespan, but reduced egg production when compared with the control diet. The results suggested a trade-off between reproduction versus somatic maintenance (stress resistance) and lifespan in B. dorsalis. Diet also had a significant effect on hatchability, and DR could increase the egg hatching success of B. dorsalis. Furthermore, DR up-regulated metabolic pathways involved in energy homeostasis and down-regulated pathways in egg production, which might mediate trade-offs between somatic maintenance and reproduction under DR regimes. The gene expression profiles in response to the acute dietary switches indicated that the digestive and metabolic pathways maybe involved in the adaptability of flies to variable dietary resources. In summary, the research facilitates a better understanding of the molecular mechanisms responsible for the B. dorsalis' phenotypic adjustments to the different qualities of the available diets.