Gastric bypass can help people seeking long-term weight loss to meet their goals. To optimize surgery outcomes, a person must make dietary changes before and after the operation.

Recovering from this surgery generally takes 6–8 weeks. During this time, an individual will move through five stages of diet changes, starting with clear liquids and ending with solid foods. The types of foods, quantities, and timing of meals significantly affect the outcomes of the surgery.

Read on to learn more about the gastric bypass diet. This article discusses the preoperative (preop) diet and gives an overview of what to expect after surgery.

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Before surgery, an individual will get information from their surgeon about the procedure and diet expectations.

Leading up to the operation, a doctor may request a person change their typical diet to a liquid diet to start weight loss. Experts need to conduct more research into weight loss before gastric bypass surgery. However, most specialists agree that modest weight loss before surgery can have beneficial effects.

Right before surgery, the surgeon will ask the person to fast (stop eating food and drinking water). Fasting for several hours before surgery ensures there are no food particles in the stomach, as this can cause surgical complications.

Learn more about gastric bypass surgery.

After surgery, the body typically takes about 6–8 weeks to heal. During this time, it needs plenty of protein to promote healing.

In general, after having gastric bypass surgery, a person can expect to eat six to eight small meals throughout the day. The meals will likely be small, at around 1–2 ounces (oz) each.

Hydration is critical to wellness after surgery. People should drink enough fluids between meals to stay hydrated but should avoid drinking fluids 30 minutes before or after eating.

Surgeons recommend a dietary protocol for people who have had gastric bypass surgery. It is important to follow a surgeon’s recommendations exactly. Below is a general overview of what the guidelines may entail.

Stage 1

Right after surgery, the stomach is delicate and in the first stage of healing. A person may expect only to have sips of water for the first 24 hours. Typical recommendations are to sip 1 oz of water each hour.

Stage 2

After 24 hours, the medical team may initiate a clear liquid diet, which may include:

  • water
  • sugar-free jello
  • sugar-free clear juices
  • clear broths
  • sugar-free popsicles

Stage 3

When a person can comfortably manage a clear liquid diet, their medical team may gradually progress them to a full liquid diet. This may include:

  • milk
  • pudding
  • tomato soup
  • creamy broth
  • yogurt
  • sugar-free protein shakes

Typically, the goal of this stage is to consume three to four small meals a day. Each meal should be high in protein, and drinking water or other clear liquids between meals is important.

A doctor may recommend a specific daily amount of liquid and protein. For example, they may recommend a person drinks 64 oz of liquids and eats 50–70 grams (g) of protein daily.

This stage generally lasts 2–3 weeks.

Stage 4

This stage starts incorporating pureed and moist ground foods. These foods have a smooth, baby food-like consistency free of chunks. This texture is gentle on the healing stomach.

Examples of stage-appropriate foods a person can puree include:

During this stage, a doctor may recommend supplementing the diet with vitamins and minerals.

This stage typically lasts 4–5 weeks.

Stage 5

During this stage, a person may start eating small portions of moist, solid foods low in sugar and fat.

It is important to continue following a doctor’s recommendations for fluid and protein intake. It is also essential to continue taking vitamin and mineral supplements.

A doctor may suggest avoiding raw vegetables for a few more weeks, as these can be difficult to digest.

A person should take tiny bites of food and chew until the food is a puree texture. At the first sign of nausea or feeling full, they should stop eating and return to the meal later.

Once the body has healed from surgery, a person cannot return to their old eating habits. They will need to adjust to a new way of eating. Following these tips can help people reach their desired results while avoiding complications.

  • Relax while eating and eat meals slowly.
  • Chew food until it is a puree texture.
  • Avoid drinking fluids while eating.
  • Stay upright after eating to avoid heartburn.
  • Avoid foods that cause gas, such as high fiber foods and carbonated drinks.
  • Avoid foods and beverages that contain added sugars.
  • Continue taking recommended supplements.
  • Prioritize quality protein while planning meals.
  • Be mindful of portion sizes to avoid overeating.

Not following a doctor’s recommendations after gastric bypass surgery can result in complications.

Dumping syndrome is a condition that may occur after gastric bypass surgery. It happens when foods high in sugar or fat move too quickly from the stomach into the intestines. It can cause abdominal discomfort, nausea, and vomiting.

Nutritional deficiencies are very common following bariatric surgery due to the body’s decreased ability to absorb nutrients.

Intestinal blockage, also called a bowel obstruction, may occur when a person eats too much food before their digestive tract is ready. It can also occur when food is too solid.

Read more about bowel obstruction.

Gastric bypass surgery is an effective way to lose excess weight. Before and after surgery, it is essential to follow the dietary protocol recommended by a surgeon. This will help promote healing, decrease possible risks, and enhance outcomes.

Not following recommendations may lead to complications and slower progress.

Recovery from gastric bypass surgery takes around 6–8 weeks, and people move gradually from consuming liquids to pureed foods to moist, solid foods.

Following recovery, it is important to adjust to a new way of eating and focus on eating small, nutritious meals.