A gastric sleeve procedure surgically decreases the size of the stomach. People who undergo this operation feel fuller faster, so it significantly reduces overeating.

After surgery, a person's stomach is about one-quarter of its original size. A person must follow a strict diet that allows the body to recover and adjust to a smaller stomach capacity.

It is best to consult a doctor or dietitian for a personalized diet plan following gastric sleeve surgery. A person who has the procedure will need to eat smaller and more frequent meals for the rest of their life.

In this article, we provide more information on the gastric sleeve diet, including what foods people can and cannot eat.

a man drinking milk as part of his diet a few days after a gastric sleeve procedureShare on Pinterest
A person can introduce liquid foods, such as milk, about 3–7 days after a gastric sleeve procedure.

In gastric sleeve surgery, a surgeon reduces the stomach to a sleeve-like shape by removing much of it.

The surgery is irreversible and can help people lose a large proportion of their body weight.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, research has shown that people lose an average of 90 pounds following a gastric sleeve procedure.

The procedure also reduces the body's ability to produce a hunger hormone called ghrelin.

In most cases, the reduced level of this hormone causes people to feel hungry less often after their surgery.

The gastric sleeve diet is a multiphase diet that experts have designed to prepare people for surgery, help them recover, and ease their transition to a lifetime of healthful eating.

However, research from 2017 suggests that gastric sleeve surgery causes nutritional deficiencies.

People who have concerns about gastric sleeve surgery might first want to try losing weight naturally by reducing their portion sizes and only including healthful foods in their diet.

After bariatric surgery, people need to introduce solid foods to their diet gradually. Doing this enables the body to get used to the new size of the stomach.

Usually, a doctor or dietitian will supervise a person's food intake following surgery. The structure of the diet plan will depend on many factors, including the extent of the surgery and how well the person tolerated it.

A specialized diet before and after surgery is important for a successful recovery.

Presurgery

Doctors will often recommend a weight management program before gastric sleeve surgery.

In a large scale study from 2015, among the participants whose body mass index (BMI) was in the highest range, those who lost 9.5% of their body weight ahead of bariatric surgery had a significantly lower risk of all of the postoperative complications that the study included.

Experts do not agree on how long a person needs to follow a diet plan ahead of surgery. However, several studies found a low carbohydrate presurgical diet plan to be more effective for short-term weight loss than a low fat option, especially for people with nonalcoholic fatty liver disease or metabolic syndrome.

Doctors recommend that people stick to a preoperative diet for 2–6 weeks to reduce the volume of the liver and the amount of fat around the organs.

While the short-term benefits of a preoperative diet ahead of bariatric surgery are clear, more research is necessary to confirm the long-term effects.

After surgery

Following surgery, people need to start by consuming smooth, soft foods and progress to eating more solid foods over time.

The table below demonstrates the safest amount of time after surgery for people to progress to the next stage of the diet. It also includes suggestions of foods to eat during each phase.

However, the exact diet will vary among individuals, depending on a person's tolerance of particular foods after gastric sleeve surgery and the overall healing and recovery time.

Some people will be able to progress to the next phase more quickly than others.

Time since surgeryRestrictionsIdeal foods
24–48 hoursDrink clear, room temperature fluids onlyMaximum half-cup servings of liquid, increasing gradually to reach at least 8 cups per day
3–7 daysIntroduce liquid foods.
  • milk
  • soy drinks
  • unsweetened yogurt
1–2 weeksMove to pureed or mashed foods
  • soups
  • mashed fish
  • pureed fruits and vegetables
  • low fat cottage cheese
  • skim milk with protein powder
  • heated, thin cereals, such as oats or cream of rice
2 weeksAdd soft foods and crackers to the diet
  • soft meatballs
  • boiled or scrambled eggs
  • cooked and peeled vegetables
  • soft, peeled fruit
  • crackers
1 monthIntroduce solid foods
  • legumes
  • fresh fruit and vegetables
  • bread
  • whole grains
2 monthsResume regular, balanced diet consisting of solid foods
  • high protein foods
  • soy products
  • eggs
  • meat
  • lentils
  • hard cheese
  • fruits and vegetables
  • the option of protein supplements if a person becomes deficient following surgery

It is vital to ensure that a person eats enough protein or takes supplements following gastric sleeve surgery. The procedure reduces the number of nutrients that the stomach can absorb, which may lead to a deficiency in the months following the operation.

People should avoid consuming simple carbohydrates, such as sugar. Instead, from about 1 month after the surgery, they should focus on consuming foods that contain a lot of fiber. A fiber-rich diet can support weight loss following surgery.

In most cases, a dietitian will create a personalized list of foods to suit the particular needs of the individual and their personal taste.

Following gastric sleeve surgery, it is important for a person to change not only the food that they eat but also how they eat it.

People will need to alter their eating behaviors to reduce the risk of postsurgical complications. Recommended adjustments include:

  • consuming between four and six smaller meals every day instead of three large ones
  • chewing thoroughly and slowly
  • ending a meal upon feeling full
  • choosing balanced meals with high protein content
  • avoiding eating due to stress or boredom, as this may reduce the long-term, positive effect of the procedure
  • taking dietary supplements, possibly on a lifelong basis due to the reduced intake of certain nutrients, including protein
  • drinking at least 1.5 liters of fluid every day
  • avoiding drinking fluids within 15–30 minutes of a meal, as this may lead to vomiting

Some foods increase a person's risk of experiencing problems after gastric sleeve surgery and other bariatric procedures. Therefore, people should exclude certain types of food and drink from their diet to reduce the chances of an adverse event.

These foods and drinks include:

  • hard and dry foods, which a person might find difficult to swallow following surgery
  • calorie dense foods and beverages, such as ice cream, cakes, chocolate, and milkshake
  • carbonated and sugar sweetened drinks, such as soda
  • foods with a high glycemic index, such as bread, rice, and potatoes, which can cause a rapid increase in blood sugar levels
  • chewing gum and foods that contribute to flatulence, such as beans

People should talk to a doctor about when it is safe to resume exercise after gastric sleeve surgery. Regular exercise can support weight loss, as well as reducing the health effects of obesity.

Weight loss may be slow at first after gastric sleeve surgery, but over a year or two, it is possible to attain a moderate weight.

People should make sure that they reintroduce solid foods slowly and adjust their eating habits for the best results and the lowest risk of complications.

Q:

What is the safest type of bariatric surgery?

A:

Surgeons aim to minimize the risk as much as possible when carrying out any procedure, but all types of bariatric surgery still carry risks. As every patient reacts differently, it is hard to determine which type is the safest.

The gastric band has the advantage of being a reversible procedure if the patient cannot tolerate it.

However, it is still not a risk-free option. Anyone considering bariatric surgery should discuss the possible risks and benefits of each option with an experienced healthcare professional before making any decisions.

Miho Hatanaka, RDN, L.D. Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.