Your bariatric diet plan: What to expect before and after surgery

Key Points

• A bariatric diet plan starts months before surgery. It involves healthy food choices and lots of fluids to help shrink the liver.
• The diet has phases, including two pre-surgery plans and four after surgery.
• Getting enough protein and water each day helps you heal and keeps you on track with your weight loss goals after gastric bypass or gastric sleeve surgery.

A bariatric diet is your step-by-step weight loss journey before and after gastric bypass or gastric sleeve surgery.

This phased approach helps:

• Prepare your body for surgery
• Supports healing
• Establish healthy eating habits for long-term weight loss success

Here are general dietary guidelines to expect before and after your procedure. The diet plans provided here are merely examples. It’s important to follow the specific diet plans provided by your medical team and bariatric dietitian.

Pre-surgery diet

Stage 1: Initial preparation (2-3 months before)

Registered Dietitian Rita Faycurry, RD, says, “In this first stage, you'll work with a dietitian to begin making healthy changes, gradually reducing portion sizes and learning new eating habits.”

This gentle introduction helps you lose initial weight while developing healthy habits that will support your long-term success.

Sample daily menu

Breakfast

• A cup of Greek yogurt with a small handful of berries

Lunch

• A medium salad (with greens)
• Grilled chicken or fish (3-4 ounces)
• Light dressing

Dinner

• About 4-5 ounces of baked lean protein (chicken, turkey, or fish)
• A cup of steamed veggies

Snacks (2-3 a day)

• A little cottage cheese
• A small handful of almonds
• A piece of fruit

Foods to avoid

• High-fat meats like bacon, pepperoni, and sausages
• Starchy vegetables like potatoes and peas
• Sugary beverages like soda or juice

Remember to include about 20-30 minutes of activity each day.

Stage 2: Shrinking your liver (2-4 weeks before)

This phase is a bit more intense. You'll likely be on a very low-calorie diet (VLCD), often with meal replacement shakes or other special foods. This means cutting way back on carbs and fats.

Why do you need to shrink the liver before surgery? Here’s the science in a nutshell.

“Your liver is near your stomach, and during bariatric laparoscopic surgery, doctors have to operate using small cuts, as small as a keyhole,” Faycurry, RD explains. “If your liver is big and fatty, it can be hard for them to get your liver out of the way during surgery. When you eat a low-sugar and low-fat diet, your liver shrinks, giving your surgical team room to do their job.”

Your surgical team will provide specific instructions, but here's a typical daily menu:

Breakfast

• A protein shake with a scoop of powder
• Some unsweetened almond milk
• A few berries

Lunch

• A protein shake or a low-calorie meal bar

Dinner

• Another protein shake or clear broth with some vegetables

Snacks (1-2 if approved by your doctor)

• Sugar-free gelatin
• Sugar-free popsicle

Important: Drink lots of water! Aim for 64 oz of water or sugar-free and low-sodium fluids or broths throughout the day.

Post-surgery diet

After bariatric surgery, your body has to get used to a smaller stomach (it’s now the size of an egg!). The bariatric diet changes in phases as you heal.

Stage 1: Clear liquids (Days 1-2)

During this most restricted period, you'll focus on clear, see-through liquids that are easy to digest and help your stomach rest.

You will start off with tiny sips throughout the day. Fluids that you may drink include:

• Water
• Sugar-free broth
• Sugar-free gelatin
• Decaffeinated tea

Your medical team will monitor your intake carefully during this time as your new stomach begins healing.

Stage 2: Full liquids (Up to 2 weeks)

Now, gradually add thicker liquids to your daily routine. This way, your stomach gets used to digesting foods a little more, and you'll start getting protein, which helps with healing. For your digestive system, it's like starting with a light exercise program after a long break.

The list of foods to expect at this stage are:

• Protein shakes (approved by your team)
• Unsweetened yogurt
• Smooth, thin soups (no chunks!)
• Sugar-free applesauce or other pureed fruits
• Low-fat milk

Sample daily plan

Breakfast (7 AM)

• ½ cup (4 oz) protein shake
• Sip slowly over 15-20 minutes

Mid-Morning Snack (10 AM)

• ¼ cup (2oz) unsweetened yogurt
• Sip slowly

Lunch (1 PM)

• ½ cup (4oz) thinned, smooth cream soup
• Sip slowly, ensuring no chunks

Afternoon Snack (4 PM)

• ¼ cup (2 oz) sugar-free applesauce
• Sip slowly

Dinner (7 PM)

• ½ cup (4 oz) protein shake
• Sip slowly over 15-20 minutes

Stage 3: Pureed foods (2-4 weeks)

Faycurry RD notes, “During this phase, you will start introducing blended foods into your diet. This gradual process lets your body get used to more solid foods, little by little. It’s also a great way to get more nutrients and protein.”

It’s best to make sure the food is super smooth with no chunks.

Foods at this stage include:

• Pureed chicken or turkey blended with broth
• Pureed vegetables like carrots, squash, or green beans
• Smooth applesauce
• Blended soft fruits
• Well-blended lentils

Sample daily plan

Breakfast (7 AM)

• ¼ cup pureed oatmeal with unsweetened milk
• ¼ cup pureed fruit

Mid-Morning Snack (10 AM)

• ¼ cup smooth, pureed cottage cheese

Lunch (1 PM)

• ½ cup pureed chicken or turkey with broth
• ¼ cup pureed carrots

Afternoon Snack (4 PM)

• ¼ cup sugar-free blended applesauce

Dinner (7 PM)

• ½ cup pureed fish with broth
• ¼ cup pureed green beans

Stage 4: Soft and regular foods (4 weeks and beyond)

This is the exciting part! You will get to eat soft, then regular, healthy foods. This includes cooked meats, soft vegetables, fruits, and other healthy things. The focus is on small portions and lots of protein. You’ll have to eat slowly and chew each bite well.

This is your transition to long-term healthy eating. It’s about building good habits and avoiding overeating or "dumping syndrome," which can happen when you eat too much or too fast after surgery.

Focus on:

• Small portions of whole grains
• High-protein foods like grilled chicken, fish, or turkey
• Soft, easily digestible items like steamed veggies
• Fruit like bananas or berries
• Low-fat dairy
• Thorough chewing
• Eating slowly

Sample daily plan

Breakfast (7 AM)

• ¼ cup cooked oatmeal with ¼ cup berries
• ½ cup low-fat milk

Mid-Morning Snack (10 AM)

• 1 soft-cooked hard-boiled egg

Lunch (1 PM)

• 3-4 ounces of grilled or baked chicken or fish
• ½ cup soft-cooked green beans or carrots

Afternoon Snack (4 PM)

• ¼ cup low-fat cottage cheese
• A few slices of banana

Dinner (7 PM)

• 3-4 ounces of baked fish
• ½ cup soft-cooked squash

Evening Snack (if needed) (9 PM)

• Small 1oz piece of cheese

💡A dietitian’s weight loss tips

Faycurry, RD says, “Staying consistent with your diet can help you adjust to your new normal, minimize discomfort after eating, and help you lose weight and keep it off. While the tips below may be intended for those who have had bariatric surgery, they are great guidelines for anyone to follow for overall health.”

• Sip water regularly between meals (aim for 64 ounces total daily)
• Never drink with meals
• Take small sips—no gulping!
• Listen to your body's fullness signals
• Chew thoroughly
• Focus on protein first
• Take recommended supplements
• Stay active as approved by your medical team
• Keep portions small
• Stop eating when you feel full

Frequently Asked Questions (FAQs)

What happens if I eat too fast after weight loss surgery?

Eating too quickly after gastric sleeve or gastric bypass surgery can cause discomfort, nausea, and even vomiting.

Your new stomach size requires a slower pace. Take tiny bites, chew thoroughly, and give your body time to signal fullness.

Why can't I drink water or juice with meals?

Because your stomach is much smaller, drinking while you eat can fill it up quickly, leaving little room for nutrient-rich foods.

Additionally, liquids can flush food through too quickly, potentially leading to dumping syndrome. Wait about 30 minutes after drinking before eating, and 30-60 minutes after eating before drinking again.

How will I get enough protein?

Protein becomes your top priority after surgery. Start with protein-rich liquids like sugar-free protein shakes, then progress to soft proteins like eggs, fish, and tender meats. Your medical team will guide you on specific protein goals, typically 60-80 grams daily.

When can I eat salads and raw vegetables?

According to Faycurry, RD, “Most people can start eating raw vegetables and salads around 6-8 weeks after surgery, but only after getting clearance from their medical team.”

Start with tender lettuce and well-cooked vegetables before attempting harder-to-digest items.

Keeping the weight off

Long-term weight loss success comes from following your bariatric diet plan closely and listening to your body's signals. Remember to take it slow—there's no rush to advance through the different diet stages.

Focus on learning your new eating patterns and giving your body time to heal and adjust.

It can be difficult to get back on your feet after surgery, return to your daily life, and stay on track with your diet. However, you do not have to do it all alone. Most insurance plans cover registered dietitian services, including bariatric nutritionists.

Find a bariatric dietitian who accepts your insurance. Discuss your options and get help on your weight loss journey.

The views expressed by authors and contributors of such content are not endorsed or approved by Fay and are intended for informational purposes only. The content is reviewed by Fay only to confirm educational value and audience interest. You are encouraged to discuss any questions that you may have about your health with a healthcare provider.