What is the biological basis for tiredness after eating? I can sometimes feel quite drowsy after some "meals" (e.g. a cold cut & cheese sandwich with juice on the side) and less drowsy (or maybe less often) after others (such as a salad). This drowsiness sometimes affects my work at the office, so I wanted to ask these questions: * What biological factors lead to the body getting tired after eating? * Are there any strategies that can be used to minimize this effect?

High carbohydrate meals will undoubtedly increase the relative levels of insulin, increase the shuttling of glucose from the blood to the cells, and leave you fatigued in wake of that. See reactive hypoglycemia. Reducing carbohydrate consumption should, to some level, reduce this effect. Caffeine should just as likely increase blood glucose levels by increasing glycogenolysis through PKA activation.

As Chris Stronks pointed out, eating can cause low blood pressure via redistribution of blood.