Bariatric Surgery Requirements: The evaluation process

Due to rising levels of obesity and life-threatening illnesses related to weight, bariatric surgery has become a standard weight-loss option. However, not everyone meets the specific criteria needed to move forward with the surgery. Here you will find our list about bariatric surgery requirements:

How much do you have to weigh to get bariatric surgery?

To determine whether you are a candidate for bariatric surgery, you need to consider a combination of factors that include weight, height, and age. These three elements combine to determine your Body Mass Index or BMI, calculated in kg/m2. Before considering this option, you must meet this bariatric surgery requirement, which was deemed essential by the Consensus Panel for the National Institutes of Health (NIH) in the 1990s.1 2

To meet the criteria, you must fall within one of three categories:

  • Have a BMI of 40 kg/m2.
  • Have a BMI ≥ 35 kg/m2 with an associated complication, such as hypertension (elevated blood pressure), diabetes, or sleep apnea.
  • Be an adolescent with a BMI ≥ 35 kg/m2 and have an underlying health condition.

Some centers may require you to show documented proof of having been obese for at least five years and having failed multiple times at guided weight-loss programs.

Also, many candidates are required to lose weight as part of the bariatric surgery process. However, this depends on your surgeon. Just how much weight is not the same across the board. Studies indicate that losing weight before the operation reduces your risk of complications after the procedure and improves long-term outcomes.3

Some centers may require you to lose 5–10% of your body weight before bariatric surgery. It varies depending on your chosen center, your doctor, and your individual physical needs. Your doctor will assess your weight loss requirements based on your particular case and any underlying health conditions you may have.2

Additional bariatric surgery requirements to keep in mind 

Meeting the weight index is the most essential of the primary bariatric surgery requirements. Apart from this, other eligibility criteria to consider

●  You are between the ages of 16-60. Though research states that age should not be a barrier to bariatric surgery, it is less risky if you don’t have underlying medical conditions.5

●  You have been unsuccessful at losing weight, despite having tried multiple weight-loss programs, having modified eating patterns, and having followed a strict activity regimen.

●  You are committed to modifying your diet and lifestyle by including more protein, healthy fats, and vegetables. Your long-term success largely depends on your commitment to adopting and sticking to these changes.

●  You don’t smoke. Smoking poses a huge risk for you as a candidate and increases your risk for postoperative complications, infections, and even death.4 If you’re a smoker, you’ll need to quit as a requirement for bariatric surgery.

●  You aren’t taking certain types of medication like NSAIDs, such as ibuprofen, nor any herbal supplements that may cause surgical complications.4

●  You have no serious health risk factors. Severe health conditions like high blood pressure and uncontrolled diabetes can pose a significant risk during surgery. Your doctor will need to assess your risk factors before you are considered eligible for bariatric surgery.5

●  You are willing to reduce alcohol consumption. Studies show alcohol consumption interferes with the healing and recovery phase and slows down weight loss. As a requirement for bariatric surgery, it is best to stop consuming alcoholic beverages.4Studies show alcohol consumption interferes with the healing and recovery phase and slows down weight loss. As a requirement for bariatric surgery, it is best to stop consuming alcoholic beverages.4

●  You are not pregnant. Pregnancy is a considerable risk factor when it comes to bariatric surgery. Research says it is best to postpone pregnancy until at least 18–24 months after the surgery. This time allows the body to adjust and stabilize weight.3

Bariatric surgery requirements: The evaluation process

Bariatric surgery requires an extensive and thorough assessment before your doctor gives you the green light. A multidisciplinary team, which consists of your doctor, dietitian, and psychologist, assesses your case and provides you with the best surgical outcome.

Medical history and lifestyle habits:

Your doctor will perform a detailed survey of related items, including:

  • A record of any underlying medical conditions such as heart disease, diabetes, kidney problems, sleep apnea, and any other significant health issues that could impact your surgical outcomes.5
  • Weight trends, obesity onset, maximum weight gained, attempts at weight loss, along with diet and medications.
  • Lifestyle habits such as smoking, alcohol consumption, dietary patterns, erratic eating, grazing, exercising, work schedule, and time constraints
  • Any history of stress or anxiety, coping strategies, and associated behaviors, like binge eating, drinking alcohol.6 7
  • Before proceeding with bariatric surgery, the multidisciplinary team should examine—and, if possible, rule out—any thyroid abnormalities or hormonal disorders that could be causing weight gain.
  • Based on your current weight and BMI, you will need to drop some weight and start taking a multivitamin to compensate for any nutritional deficiencies.6 4

Psychological evaluation:

Before undergoing bariatric surgery, the team must evaluate your emotional and mental state. Your doctor must assess your willingness and readiness to undergo surgery, undertake the required preparation, and commit to making nutrition- and activity-related changes to obtain a positive outcome.4 5

Also relevant is whether you have a history of anxiety or depression and whether you have ever taken medication for these issues. If so, your doctor may be able to provide the support or counseling you require.

Lab testing:

Bariatric surgery requirements include additional blood tests to assess your blood sugar, cholesterol, fasting lipids, hormone, and liver functioning levels.

An electrocardiogram, also known as an ECG or EKG, may be needed to rule out a heart condition. If necessary, the team may recommend an abdominal ultrasound and sleep apnea test.4 5 

If your doctor approves your bariatric surgery, the next step includes a preoperative visit, described in the following section.

Preoperative visit

Well done! You’ve made it this far. Before undergoing bariatric surgery, the team will provide you with information about your detailed preoperative plan, which may begin weeks or even months before the procedure.

●  Calorie restriction. Your doctor will start you on a low-calorie, high protein diet in preparation for bariatric surgery.2 This regimen does two things; it triggers weight loss and reduces the size of your liver. These effects can improve the outcome of your surgery.

●  Preoperative counselling and educational support. Preparation, in the form of preoperative counseling and education, is crucial for bariatric surgery and helps you to understand and accept lifestyle changes, a new weight loss regimen, and the determination you’ll need to maintain a healthy weight.5 This phase provides the opportunity to voice any concerns, anxieties, or fears you may have regarding the surgery or long term changes.

●  Nutritional support. Depending on your health, a multivitamin may be prescribed to you to offset any dietary deficiencies. You may also need to take protein supplements to help your body heal faster after surgery.4

●  Quit smoking and alcohol.

●  A liquid diet. Two weeks before the surgery, you will likely begin a liquid diet. The purpose of this is to reduce the fat around your liver to promote a safer and more efficient surgery.

●  Financial support and plan. Bariatric surgery can be effective. It can also be expensive. Speak with your doctor and explore the financial options available via your insurance or healthcare provider.


The information provided in this article covers your basic guidelines only. For a personalized and detailed assessment of bariatric surgery requirements, please consult your primary care doctor or licensed healthcare provider. Always seek professional help before making any decisions.


  1. Treatment of obesity.
  2.  Preoperative weight loss and bariatric surgery.
  4. Bariatric metabolic surgery.
  5. Preop evaluation in Bariatric surgery.
  6. Journal of laparoendoscopic surgery 2018.
  7.  Obesity surgery preop assessment.

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