|MadSci Network: Anatomy|
Aloha, Brian, The immediate answer to your question is that I cannot confirm that it takes 3 months to digest a hamburger. Now to the particulars. Incidently, I am a Ph.D.-level nutitionist, by training, and have taught here at the University of Hawai`i at Manoa for almost 13 years, now. I teach large introductory nutrition classes of students from all across the university. Your question is not unlike those that I get in class every day, so I feel pretty comfortable answering it. If you are talking just about the hamburger meat or if you are talking about a hamburger sandwich with all the trimmings, the answer is about the same. It takes about 24-72 hours for most people's digestive tract to do its job on the food eaten...depends on the person, the food, the person's state of health, medications they might be on, their emotions, etc...but, on the whole 1-3 days will completely digest, or break apart, the food. Scientists are actually able to measure this by 'marking' the meal with some type of dye that eventually colors the feces (semi-solid matter that eventually is eliminated from the body via the anus...as a bowel movement), so they can see when the residue of something actually exits the body. Once the food is broken apart into its component parts (the macronutrients: protein, fat, carbohydrate, water; the micronutrients: vitamins, minerals), the breakdown products can then be absorbed into the body. Almost all of this occurs by the time the materials reach the small intestine. So the food (hamburger and trimmings) that you eat for dinner tonight will be in the form of amino acids (protein), triglycerides and cholesterol (fats) and carbohydrates (mostly glucose), vitamins, minerals, and water probably by tomorrow evening...and probably some, if not most, of it will also have been absorbed into your body and used in some way. I hope this helps clear up any misinformation that you might have heard on the radio about digestion and absorption of your food. Incidently, the best resource for getting good nutrition information may not be the radio, TV, magazines, or the internet. For questions related to nutrition, if possible, talk with someone (like me or a dietitian at your local hospital or health care clinic) who has been trained in nutrition. A lot of folks think they are experts in nutrition, but you should look for either R.D. behind the person's name or ask if they have any advanced degrees (like M.S., M.P.H., or Ph.D.) in nutrition or a related subject from a college or university that offers training in nutrition.
Try the links in the MadSci Library for more information on Anatomy.