If you’ve had weight loss surgery (WLS) and suddenly feel a weird pain under your ribs, it’s worth a closer look. Your digestion is rewiring itself, and sometimes that change stirs up trouble in places you didn’t expect — like your gallbladder.
Gallstones after bariatric surgery are one of the most common (and most surprising) side effects of rapid weight loss. But the good news? They’re manageable. Let’s unpack what’s actually happening, what to watch for, and how you can stay ahead of it.
Why gallstones form after bariatric surgery
WLS rearranges how your guts and digestion signals operate. You’re eating itty-bitty amounts, losing weight fast, and your liver is working overtime to process stored fat. Normally, when you eat, a bit of fat tells your gallbladder to contract and squeeze out bile to help digest it.
After surgery, you’re often eating very low-fat, teeny tiny meals. That means the gallbladder doesn’t get its usual “squeeze” signal. The bile hangs around longer, thickens, and small crystals can form — that’s where stones begin.
Combine that with rapid weight loss and hormonal changes, and it’s a perfect storm for gallstones. They’re common enough that most bariatric teams talk about them early on, but they still catch plenty of people off-guard.
Could you already have gallstones before surgery?
Absolutely. Gallstones can exist quietly for years. Obesity, high-fat diets, or genetics all increase your risk, so plenty of people head into surgery already carrying a few without knowing it.
Symptoms can be vague — bloating, random stomach discomfort, nausea after greasy foods — so it’s easy to miss. If you’ve ever had that upper-right-side ache, mention it to your surgeon.
How to check: ask your team for a quick ultrasound before surgery. It’s the easiest way to spot stones early. If they’re there but silent, your surgeon may simply note it and keep an eye on you post-op.
How common are gallstones after gastric sleeve or bypass?
It depends on your procedure and how fast you lose weight. Research puts it anywhere from 10% to 50% of people developing new gallstones in the first year after bariatric surgery. Most appear within the first six months, when weight loss is fastest.
Red flags to look for
- Sharp or crampy pain under the right ribs (can travel to the back or shoulder) — gallbladder irritation or a moving stone
- Nausea or vomiting after a meal — possible blocked bile flow
- Fever, chills, or yellowing of eyes/skin — infection or a stuck stone; get checked immediately
Because your digestive system is still settling, these can blur into the usual post-surgery weirdness — but trust your gut if something feels off.
Managing gallstone risk while you heal
Early after weight loss surgery, “eating regularly” looks very different. You’re moving through phases — liquid → soft/purée → solid — and your portions are mini. You can’t snack your way out of gallstones; focus on consistency instead.
What helps:
- Stay hydrated — thicker bile happens faster when you’re dehydrated.
- Keep protein steady — use shakes or yoghurt during liquid and soft stages to meet nutrition goals.
- Add a little healthy fat once your team clears it (soft/solid stages): a teaspoon of olive oil, a bit of avocado, salmon, or yoghurt with some natural fat.
Here’s the weird twist: both too much and too little fat can cause gallstones.
Before surgery, a high-fat diet can overload your bile with cholesterol, thickening it. After surgery, ultra-low fat intake does the opposite — your gallbladder barely gets used, so bile just sits and crystallises. The goal isn’t “fat-free,” it’s fat-smart — small, steady amounts that keep things moving without overloading the system.
If you use protein powders, mixing with milk, yoghurt or avocado can add a gentle fat signal once tolerated. Helpful, not a cure — but it supports that smooth gallbladder rhythm your body’s relearning.
Non-surgical options for gallstones after WLS
If gallstones appear, surgery isn’t automatically next.
- Ursodeoxycholic acid (UDCA / ursodiol) – can help dissolve cholesterol-type stones or reduce new ones in early months post-op (available in NZ and AU; doctor decides).
- Monitoring – silent stones often just need awareness and follow-up.
- Less-invasive procedures – lithotripsy (breaking stones with sound waves) or endoscopic removal (ERCP) if a stone blocks a duct.
If stones keep flaring or infection risk rises, gallbladder removal becomes worth discussing — but it’s not the only path.
Can you get checked for gallstones before surgery?
Yes. If you’ve ever had upper-right-side pain or trouble after fatty foods, ask for an ultrasound during your pre-op workup. It’s quick and gives your team a heads-up. Some surgeons treat or remove a clearly problematic gallbladder at the time of WLS; others prefer to wait and see.
The takeaway
Gallstones after weight loss surgery aren’t rare, but they’re manageable. They’re just another quirk of a body that’s healing and adapting fast.
Keep hydrated, don’t fear small amounts of healthy fat, and listen to your body — especially if those right-side pangs show up after eating.
If in doubt, get checked. You’re not overreacting — you’re advocating for the body that’s working overtime to build its new normal.
Note: This article is general information only. Always follow your surgeon or dietitian’s advice.