Almost 600K people globally have bariatric surgeries every year. However, not all candidates qualify for the procedure right away as there are certain aspects that contribute to their eligibility: specific body mass index (BMI), the amount of excess weight, and comorbidities.

Although the weight loss procedure helps people struggling with obesity to return to a healthy weight and improve their quality of life, it is typically performed when a person has a BMI of 35 or more. Patients with a BMI of 30 with existing weight-related comorbidities—diabetes, high blood pressure, sleep apnea, or similar conditions are also considered for the surgery. Yet, according to Almantas Maleckas, MD, PhD, a surgeon at Nordbariatric, a leading bariatric surgery center in Kaunas, to minimize any potential risks associated with the procedure, if a person’s BMI exceeds 35, they are asked to lose a certain amount of excess weight—usually between 2-15 kg—before the surgery.

Why does a person need to lose weight prior to surgery?

“Losing some weight before the surgery is a really important step due to several reasons. First of all, a high amount of fat surrounds the inner organs, therefore, during gastric bypass surgery, the small bowel needs to be mobile enough to allow the surgeon to safely form the new connection with the gastric pouch,” Almantas Maleckas said. “If the amount of fat is not reduced in preparation for the surgery, the surgery might become too difficult or risky.”

Another reason for losing excess weight before the procedure is liver condition. The organ has to be lifted during the surgery, and if it is too oily due to excess weight, it might crack and bleed when lifted. Therefore, if the patient reduces their weight by 2-15 kg (depending on their initial BMI), the size of the liver decreases as well, at the same time eliminating the risk of complications.

There are many ways to go about it if you want to lose weight. Watching your diet is essential to make sure you’re adding nutrition not fat or too many carbs. Balancing your nutrition with supplements will help, but only if you’re also eating the right foods in the first place. Exercise is also essential as it will push your system to burn fat and balance out your weight and overall health. Start with some easy exercises, don’t push yourself too hard. Exercise should be a gradual process that starts where you are and gradually becomes a more intense workout over time. You’re not just trying to lose weight, you’re trying to build a healthy overall system

Requirements regarding pre-existing conditions

Gastric bypass surgery has been said to improve the management of some comorbidities—type 2 diabetes, for instance. “The procedure can speed up diabetes remission, and allow to manage high blood pressure better” the surgeon explained.

However, only people who take medication for their comorbidities qualify for the surgery. If a person has diabetes, which is not treated with medication, they need to adjust the blood sugar levels with drugs before applying for weight loss surgery, because the potential benefits of the procedure must not outweigh the risks posed by non-treated comorbidity.

Expert-approved options for pre-op weight loss

People who need to lose excess weight in order to reduce their liver size and avoid any possible complications should follow a specific diet, Almantas Maleckas indicated.

“The bariatric diet intended to reduce the liver size prior to the surgery involves reducing the amount of glycogen (a storage form of carbohydrates), water, and fatty deposits in the liver, which makes the organ safe for lifting during the intervention.”

The pre-surgery diet should contain up to 900 calories per day and be low in sugar and fats. Although patients usually need to follow it for about two weeks prior to the procedure—those with a higher BMI (50 or more) might be required to extend it up to three weeks.

The surgeon named three dietary options which can be combined throughout the week if necessary: restricted food portions, a calorie-controlled diet, and meal replacements. Restricted food portion diet consists of 100 g of carbohydrate per day, and moderate amounts of protein, fat, and sugar. This option contains varied, balanced, low-calorie meals from different food groups: vegetables, meat, fruit, low-fat dairy products, etc.

The calorie-controlled diet focuses on 800 calories per day but is otherwise customized by the person themselves, with the main condition that it has to be low in sugar and fat, and contain fruit and vegetables. The third option consists of meal replacements—milkshakes, smoothies, soups, or protein bars—combined with light meals.

Before committing to a certain pre-surgery weight loss diet, people should consult with their surgeons or bariatric dieticians, and make sure to take into account any pre-existing conditions and the required medication.