Feeling tired and sleepy after eating can be a normal bodily response. It can be caused by several factors, including: hormones released during digestion eating foods that contain the amino acid tryptophan, which can encourage sleepiness lack of good quality sleep, which can make you feel more tired after eating lack of regular exercise, which puts you at risk of low energy in general Feeling tired after a meal can sometimes be a sign of an underlying medical condition, including: diabetes food intolerance or food allergy obstructive sleep apnoea anaemia underactive thyroid coeliac disease Speak to your doctor if you regularly feel tired after eating.