Final answer:
A reliable tool used by a dietitian to measure food intake consistently delivers the same results under the same conditions. However, it's crucial that the tool is also valid, meaning it accurately measures what it is intended to measure.
Step-by-step explanation:
If the tool that the dietitian is using to measure food intake is reliable, it means that the tool provides consistent and accurate results each time it is used. Reliability in this context refers to the consistency of the measurements made by the tool, such that repeated measurements under the same conditions yield the same results. However, it is important to note that while a tool may be reliable, it also needs to be valid to be useful. Validity addresses whether the tool accurately measures what it is supposed to measure. Without both reliability and validity, a measurement tool might not provide the most accurate assessment of dietary intake, similar to how a miscalibrated kitchen scale might consistently give wrong measurements of cereal even if it is reliable.