The mammalian target of rapamycin (mTOR) pathway coordinates cell growth in response to nutrient availability. Increasing evidence points to a role for mTOR to also direct whole-body energy balance in response to micronutrient as well as hormonal cues. This positions mTOR as a key central integrator of acute and chronic changes in fuel status. Energy balance is affected by mTOR in several organ systems, including the hypothalamus, where the pathway can modulate feeding. We propose that a greater understanding of this nutrient-sensitive pathway may open the door to more intelligent, effective diet design based on the effects of micronutrients on specific signaling pathways.