Methods and systems discriminate between food and drink intake, optionally with a single temperature sensor positioned in a patient's stomach. Ingestion events may be detected and the substance ingested is classified as either food or drink based on several characteristics of the intra-gastric temperature signal from before, during, and after ingestion. Multiple ingestion events making up a meal may be detected and classified such that the entire meal can be classified as food only, drink only, or mixed food and drink. Treatments to a patient may be at least partially based upon the detection and classification of ingestion events. A method of preparing an intake classification algorithm using a training set of temperature data is also provided.