Bill W

Calories in normal stomach vs Gastric bypass stomach

2 posts in this topic

Using a 300 calorie meal as an example, asuming the normal stomach absorbs 100% of the calories, what percentage of calories is absorbed or not absorbed in the gastric bypassed stomach? Thanks for all your help to others Dr. Callery

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Using a 300 calorie meal as an example, asuming the normal stomach absorbs 100% of the calories, what percentage of calories is absorbed or not absorbed in the gastric bypassed stomach? Thanks for all your help to others Dr. Callery

Your food is absorbed by your small intestine. The stomach churns up your food, and the stomach juices start the digestive process. After a gastric bypass you will probably still absorb 100% of the calories that your eat. There is less absorption of B12 and Iron, possibly of Calcium, but unfortunately not of calories.

Having a small stomach makes it harder to eat a lot at one time, and it makes the digestive process less efficient. But our digestive tract has more than enough length to do the job even with moderate bypass of the small bowel. The gastric bypass also makes you less hungry, and perhaps resets your weight "set point" at a much lower level.

If the surgeon bypasses a great deal of the small bowel such as with the duodenal switch procedure, there may be protein/calorie malabsorption as well. But most surgeons don't do this procedure because of the side effects such as frequent diarrhea and really bad gas.

So, bottom line with the gastric bypass and the other procedures: the procedure is like power steering, not auto pilot. It will help you eat less and feel less hungry at a lower weight, but ultimately, it's up to you to avoid snacks, eat small quantities of healthy food, and keep your body moving as much as you can.

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