Preparing for Surgery: A Timeline
A practical timeline for consultations, clearances, the pre-op diet, medication planning, and final preparations before bariatric surgery.
On this page
Getting ready for weight loss surgery involves more than the operation itself. Most programs require a series of steps in the months and weeks beforehand, from a pre-op diet to psychological evaluation to medical clearances. This page walks through the general order, with links to the detailed pages on each step.
Months out: building the foundation
Early preparation usually includes required consultations (surgical, nutritional, and psychological), any medically supervised weight loss your insurer requires, and getting a full picture of what to expect. If you're on a GLP-1 medication, this is also the time to talk with your surgical team about how it factors into your pre-op plan, since timing around surgery matters. See Pre-Op Diet Overview for what the required weight loss period typically involves.
The psychological evaluation
Most bariatric programs require a psychological evaluation before approving surgery. This isn't a pass/fail judgment of your character. It's meant to identify any untreated mental health conditions, eating disorders, or substance use issues that would benefit from support before or alongside surgery, and to make sure you have a realistic understanding of what surgery does and doesn't do. Being honest during this evaluation, rather than telling the evaluator what you think they want to hear, leads to a better outcome, since it's meant to set you up with the right support, not to gatekeep the surgery unnecessarily.
Weeks out: the pre-op diet
Most programs require a strict pre-op diet for one to three weeks immediately before surgery, typically a low-calorie, high-protein liquid diet. The goal is to shrink the liver, which sits directly over the stomach and makes surgery safer and technically easier when it's smaller. This diet is often the hardest part of the entire process for many patients, and it's worth taking seriously: skipping it or not following it closely can affect whether your surgery proceeds as scheduled.
Days out: final preparations
In the final days before surgery, you'll typically get specific instructions on when to stop eating and drinking, which medications to pause or continue, and what to bring to the hospital. This is also the time to prepare your home for recovery: stock easy-to-prepare foods for the post-op diet stages, arrange help for the first few days, and set up a comfortable recovery space, ideally somewhere you won't need to climb stairs repeatedly.
Medical clearances
Depending on your health history, your surgical team may require clearance from other specialists, such as a cardiologist or pulmonologist, before approving surgery. These clearances exist to catch and address any risk factors ahead of time rather than during the operation, and they're a normal part of a thorough pre-op workup, not a sign of a problem specific to you.
When to talk to your care team
Contact your surgical team promptly if you get sick in the days before surgery, if you're struggling to follow the pre-op diet and worried about compliance, or if you have questions about any medication (including GLP-1s) that you're unsure whether to continue.
Sources and references
- Eisenberg D, Shikora SA, Aarts E, et al. (2022). 2022 ASMBS and IFSO Indications for Metabolic and Bariatric Surgery. Surgery for Obesity and Related Diseases, 18(12), 1345-1356. DOI: 10.1016/j.soard.2022.08.013 doi.org
- Chang SH, Stoll CRT, Song J, Varela JE, Eagon CJ, Colditz GA (2014). The Effectiveness and Risks of Bariatric Surgery: An Updated Systematic Review and Meta-analysis, 2003-2012. JAMA Surgery, 149(3), 275-287. DOI: 10.1001/jamasurg.2013.3654 doi.org
- Mechanick JI, Apovian C, Brethauer S, et al. (2020). Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures, 2019 update. Surgery for Obesity and Related Diseases, 16(2), 175-247. DOI: 10.1016/j.soard.2019.10.025 doi.org
- Stenberg E, Szabo E, Ågren G, et al. (2014). Early Complications After Laparoscopic Gastric Bypass Surgery: Results From the SOS Registry. Annals of Surgery, 260(6), 1040-1047. DOI: 10.1097/SLA.0000000000000431 doi.org