Does your stomach really shrink when you eat less?

As a specialist in weight loss, I hear this phrase a lot, “I just need to shrink my stomach so I can get used to eating less.”

In reality, throughout life, the adult stomach stays about the same, which is the size of a football. However, the stomach is a muscle that can be stretched temporarily to fit more in should the occasion occur. How much we eat tends to be more dictated by habit and hormones rather than size, however.

A little anatomy for you. (I promise, just a little.) There are three very basic parts of the stomach: the top (the fundus), the middle (the body), and the bottom (the pylorus), which is where food empties out into your intestines. The the fundus, is the stretchy part that can expand a bit to allow more food to fit if necessary. It is not likely that the entire body of the stomach is going to expand to allow more food. Back to the football, if you can visualize how much chewed up food that would really mean, it’s quite a lot. However, our body regulates our appetite with hormones that send signals to our brain to tell us whether we’ve eaten enough or not – this is independent of how full the stomach is. Those hormones play a very big role in weight regulation and can be easily over-ridden by outside cues (i.e. the food tastes really good, it’s Thanksgiving, etc.)

Now back to the fundus. This upper muscle is why there’s always room for dessert, but maybe not another immediate meal. It takes about two full hours for the meal to completely empty down to the lower  stomach, out and travel into the small intestine. If you overdo it by eating too much too fast or adding some dessert at the end, that fundus is going to allow for some extra room. For those that habitually overdo it, the tolerance is going to grow over time for allowance. For those that don’t, it’s gonna be more uncomfortable and you’ll be less likely to keep doing it. When you go on a diet and purposely under eat for a couple of weeks, that fundus will become less stretchy and you’ll feel like your stomach has “shrunk.” But it really hasn’t. Weird, huh?

Competitive eaters use this to their advantage and train that muscle over time to allow them to eat a lot in one sitting without puking. I’m not suggesting you do that since I’m assuming you read my blog for help with weight loss, not competitive eating.

In someone who has had weight loss surgery, the body and possibly the pylorus of the stomach has been removed or bypassed, leaving about the size of an egg left. That’s not a lot and it creates some massive restriction. Because this part of the stomach is a muscle and can still stretch, it doesn’t stay that restricted for good. However, the tolerance for over-eating is much less, so the individual usually never gets back to having a football size stomach and still experiences permanent food restriction. If you know someone who had weight loss surgery and regained all or some of their weight because they “stretched their stomach back out,” this may be what’s going on. That’s for another blog post, though.

Hope you found this helpful and enjoyed a little weird science today!

P.S. If you’re looking for online support with like minded women striving to live a healthier lifestyle, you may be interested in joining my free online support group here.

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Jillian McMullen, RDN, CSOWM, LDN

2 thoughts on “Does your stomach really shrink when you eat less?

    1. haha, you are too funny! it’s hard to actually spot shrink without losing weight in general, but I do have some thoughts if you are open to natural options. You can send me a message on Facebook if you’d like.

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