Usersg, If your light-headed spells & fainting are happening shortly after meals, you might be suffering from post-prandial hypotension (i.e. low blood pressure after eating). What happens in this condition is that the rush of blood to the digestive system following eating causes the blood pressure to drop too low, which results in feeling faint or fainting. It's similar to vasovagal syncope, which KathM mentioned. Indeed, many people with vasovagal syncope find that they often experience symptoms after eating. They often do better if they eat little and often rather than eating 3 larger meals a day.Fainting can be related to IBS because an extremely strong bowel contraction can sometimes cause a vasovagal reaction, as can straining to have a bowel movement. However, you can get injured when fainting so I think you really should get checked out to see if you've got postprandial hypotension &/or vasovagal syncope.I suffer from vasovagal syncope & postural tachycardia sydrome which cause me feel faint several times per day and actually faint several times per week so I know how you feel.Good luck,ClareM