When a patient comes to us regarding bariatric treatment, we do not assess their situation based solely on BMI. The decision is made by a multidisciplinary team after a comprehensive assessment of the patient's health, obesity-related conditions, weight history, and previous treatment. BMI remains an important criterion, but it is only one component of the overall clinical picture.
BMI is indeed important. It is a simple indicator that helps assess the relationship between body weight and height.
But BMI is only one part of the clinical picture.
The same number on the scale can correspond to completely different health conditions. One person may have no significant obesity-related diseases. Another person with the same BMI may already have type 2 diabetes, arterial hypertension, sleep apnea, fatty liver disease, or significant limitations in physical activity.
Therefore, the question "Do I need bariatric surgery?" cannot be answered using a single calculator.
What Does BMI Show?
Body mass index is calculated using a simple formula: body weight in kilograms divided by height in meters squared.
This indicator is useful because it is easy to calculate and can be used for an initial assessment. However, it has an important limitation: BMI does not show body composition or indicate how adipose tissue is distributed throughout the body.
The American Society for Metabolic and Bariatric Surgery (ASMBS) also notes the limitations of BMI as a measure for assessing patients with obesity. BMI does not fully reflect the distribution of adipose tissue or individual health risks.
Therefore, BMI should be considered a starting point rather than a final answer.
Why the Same BMI Can Mean Different Health Conditions
Imagine two patients with a BMI of 35 kg/m².
The first has no diabetes, normal blood pressure, no significant sleep-related breathing disorders, and relatively preserved physical activity.
The second, with the same BMI, has already been diagnosed with type 2 diabetes, arterial hypertension, and obstructive sleep apnea.
Formally, the number is the same.
Clinically, these are two different situations.
That is why patient assessment should focus not only on body weight but also on the consequences of obesity that have already developed in the body.
This is a fundamental principle for our team.
"We do not operate on a BMI number. We treat obesity as a disease and assess the patient comprehensively. That is why it is important for our team to understand not only the patient's current weight but also their weight history, the presence of obesity-related diseases, previous attempts at treatment, eating habits, and overall health. Only after such an assessment can we determine whether surgical treatment is appropriate and which approach is optimal for the individual patient."
Emir Useinov Tair, Bariatric Surgeon
What Do We Assess Besides BMI?
Before discussing surgery, it is important to obtain a complete picture of the patient's health.
How Has the Weight Changed?
Current body weight is not the only factor that matters.
It is important to understand:
- when significant weight gain began;
- what the patient's maximum weight was;
- whether they were able to lose weight independently;
- how long the result was maintained;
- whether weight was regained;
- which weight-loss methods had already been tried.
A patient's weight history helps us understand the course of the disease and the body's previous response to treatment.
Are There Obesity-Related Diseases?
Particular attention is paid to conditions that may develop or progress in the setting of obesity.
Depending on the individual situation, these may include:
- type 2 diabetes;
- arterial hypertension;
- obstructive sleep apnea;
- lipid metabolism disorders;
- metabolic dysfunction-associated fatty liver disease;
- joint diseases;
- cardiovascular diseases;
- gastroesophageal reflux disease.
The presence of these conditions matters not only when determining whether surgery is indicated. They may also influence the choice of a specific surgical procedure.
Why Modern Bariatric Surgery Is Not Limited to BMI
Over the past several years, our understanding of obesity has changed significantly.
Today, obesity is viewed not simply as excess body weight but as a chronic disease that can affect the function of multiple organs and systems.
That is why current recommendations consider metabolic and bariatric surgery based not only on BMI but also on the patient's overall health.
According to the 2022 ASMBS and IFSO guidelines, metabolic and bariatric surgery is recommended for patients with a BMI ≥35 kg/m² regardless of the presence or absence of obesity-related comorbidities. For patients with a BMI of 30-34.9 kg/m², surgical treatment may also be considered in certain clinical circumstances, particularly in the presence of metabolic disease and insufficient results from non-surgical treatment. ASMBS/IFSO Guidelines
This does not mean that every person with a certain BMI automatically needs surgery.
It means that the decision should be based on the complete clinical picture.
Why Is Waist Circumference Important?
Another measurement that can complement patient assessment is waist circumference.
BMI does not show where adipose tissue is predominantly located.
At the same time, abdominal obesity has independent clinical significance. Therefore, in certain situations, information about height and weight alone is not sufficient.
Additional assessment can provide a better understanding of body composition and the patient's metabolic risks.
What If the BMI Is High but the Person Feels Healthy?
This is one of the questions that often comes up during consultations.
"If I don't have diabetes, blood pressure problems, or other diseases, why would I need surgery?"
There is no universal answer based on a single measurement.
A high BMI is itself an important risk factor, but when making a decision, we assess the entire situation:
- the patient's age;
- duration of obesity;
- weight trajectory;
- comorbidities;
- previous treatment attempts;
- eating habits;
- level of physical activity;
- test and examination results;
- the potential benefits of surgery;
- the possible risks of the specific procedure.
That is why a bariatric treatment consultation should not be reduced to checking a single number against a table.
What If the BMI Is Below 35?
It is particularly important not to rely on the outdated rule that "a BMI below 35 means surgery is impossible."
Modern recommendations are more flexible.
In patients with a BMI of 30-34.9 kg/m², surgical treatment may be considered in the presence of metabolic disease and insufficient results from non-surgical treatment. The decision is made on an individual basis.
Therefore, it is incorrect to tell a patient simply, "Your BMI is not high enough," or, conversely, "Your BMI is high enough, so you definitely need surgery."
The individual patient must be assessed as a whole.
What Information Do We Assess Before Surgery?
During the preparation for surgery, we evaluate several groups of information.
1. Anthropometric Measurements
BMI, body weight, height, waist circumference, and weight trajectory.
2. Metabolic Status
Blood glucose levels, markers of carbohydrate metabolism, lipid profile, and other parameters when indicated.
3. Comorbidities
Diabetes, arterial hypertension, sleep apnea, liver disease, cardiovascular disease, joint problems, and other conditions associated with obesity.
4. Treatment History
Which weight-loss methods the patient has already tried and how sustainable the results were.
5. Eating Behavior
The number and nature of meals, episodes of overeating, tolerance of different foods, and other characteristics that may be relevant when choosing treatment.
6. Preoperative Risk
The patient's overall health, examination results, medications they are taking, and factors that may affect the safety of the surgical procedure.
After this assessment, it is possible to discuss not only whether surgery is indicated, but also which treatment option is likely to be the most appropriate for the individual patient.
BMI Remains an Important Indicator
I would not contrast the modern approach with BMI.
BMI remains a useful tool. It helps standardize the assessment of body weight and is included in current criteria for selecting patients for metabolic and bariatric surgery.
The problem arises when it is used as the only indicator.
ASMBS itself notes the limitations of BMI as a tool for assessing obesity.
Therefore, in my practice, I consider BMI one element of a comprehensive patient assessment.
It is important for me to see not only the number on the scale but also the history of the disease, its consequences, and the patient's actual health status.
What Should Patients Know Before a Consultation?
If you are considering bariatric surgery, it is helpful to prepare the following information in advance:
- how your weight has changed over the past several years;
- what your maximum weight was;
- which weight-loss methods you have already tried;
- which medications you have taken;
- which diseases you have been diagnosed with;
- which medications you are currently taking;
- whether you snore, experience pauses in breathing during sleep, or have significant daytime sleepiness;
- whether you experience heartburn or reflux;
- how excess weight has affected your quality of life.
The more complete the information, the more accurately your situation can be assessed.
BMI can be calculated in a few seconds.
But the decision about surgical treatment requires much more than that.
Emir-Useinov Tair Seitkhalilovich
Surgeon and bariatric surgeon at the Bariatric Surgery Center based at Kyiv City Clinical Hospital No. 1. Specialization: bariatric and laparoscopic surgery.
