MadSci Network: Anatomy

Re: How long does a hamburger take to digest?

Date: Thu Mar 14 18:45:11 2002
Posted By: Dian Dooley, , Associate Professor, Food Science and Human Nutrition, University of Hawaii at Manoa
Area of science: Anatomy
ID: 1015553249.An

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 a bowel 
movement), so they can see when the residue of something actually exits the 
     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.

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