Bariatric Surgery: Dr Ganesh’s Guide to Weight Loss Surgery (2021)

Still at a loss because your weight loss regime hasn’t worked? There’s one option that could help you – bariatric surgery. If you’re obese with a BMI over 40 and have other weight-related problems, bariatric surgery may be able to help you. When all else fails, bariatric surgery can help you to eat less, feel full and eventually lose weight. Let’s find out exactly how.

What is bariatric surgery? 

Bariatric surgery refers to a set of surgical procedures meant to help people to lose weight by altering the digestion process such that less calories are absorbed. It is often used to treat obesity where there is excess fat leading to other health issues.

Who is bariatric surgery for? 

Bariatric surgery is typically only recommended if conventional methods of reducing weight have failed, such as through diet restrictions or exercise. 

For you to qualify for bariatric surgery, your BMI should be above 40, combined with severe weight-related health conditions. BMI is your weight in kilograms divided by the square of your height in metres. A BMI of about 20 – 23 is considered to be healthy. 

Severe weight-related health conditions include type 2 diabetes, high blood pressure, arthritis, heart disease, and severe obstructive sleep apnea.

What are the types of bariatric surgery? 

In Singapore, bariatric surgery can be performed in two ways, the “open” method or the laparoscopy method. The “open” surgery involves cutting the abdomen open whereas the laparoscopy method involves guiding surgical instruments into the abdomen using smaller, half-inch incisions. Like many experienced doctors, I personally prefer the laparoscopy method because the required cuts are much smaller, causing little tissue damage and leading to lesser complications post-op, which means you can possibly be discharged faster. 

There are 4 types of bariatric surgery: 

  1. Vertical sleeve gastrectomy (VSG) 
  2. Adjustable gastric banding (AGB) 
  3. Roux-en-Y gastric bypass (RYGB) 
  4. Biliopancreatic diversion with a duodenal switch (BPD-DS) 

Each surgery has pros and cons and other factors that affect patient suitability, including BMI, eating habits, other health problems and previous surgeries. To find out which approach is most suited for you, talk to your doctor to weigh the benefits and risks. 

Vertical sleeve gastrectomy (VSG)

This procedure removes about 80% of the stomach that leaves a long pouch as the stomach. The stomach is hence smaller and cannot hold as much food, so you will be full even when you eat less. Also, it produces less of the appetite-regulating hormone known as ghrelin, which helps to reduce your desire to eat. 

This procedure has 3 advantages:

  1. Significant weight loss 
  2. No rerouting of the intestines 
  3. Shorter inpatient stay

Adjustable gastric banding (AGB)

This surgery places a band around the upper part of the stomach in order to reduce the size of the stomach so that food intake will be restricted. The band around the stomach will be tightened progressively. Gastric banding will work if patients are motivated to stick to dietary plans and exercise regularly, and can even provide some freeway should you wish to gradually increase your calories over time. 

An advantage of AGB is that it is reversible — so if you’re confident that you can manage your diet once you hit your goal weight, you are more than encouraged to remove the band. 

Roux-en-Y gastric bypass (RYGB) 

This is the most common method that uses gastric bypass, and is typically permanent and irreversible. 

The surgeon will separate the upper part of the stomach from the lower part. The upper part becomes a pouch that will be connected to the small intestine, also called the ”Roux limb”. This smaller stomach will hold smaller amounts of food, thereby restricting food intake. 

The surgeon also reroutes the digestive system to bypass the stomach and part of the small intestine, so that you will absorb less calories and nutrients, thereby achieving the goal of weight loss. 

This procedure has 2 advantages:

  1. More significant and rapid weight loss than other procedures.
  2. Comorbidities such as type 2 diabetes and high blood pressure may improve before you even lose much weight. 

Biliopancreatic diversion with duodenal switch (BPD-DS) 

This is a two-part surgery. The first part of the surgery is similar to a sleeve gastrectomy. The second part of the surgery will then connect the later part of the intestine to the duodenum (the first part of the small intestine), thereby doing a bypass of most of the small intestine. 

As a BPD-DS is the most complicated out of all the other bariatric surgeries, I only recommend it for patients with morbid obesity.

Does bariatric surgery hurt?

There may be some pain at the incision site, and there may be soreness in the neck and shoulders. It is normal to feel some discomfort post-surgery, but keeping the pain in control is important for recovery. Part of my post-surgery care includes “patient-controlled analgesia” where you are administered with pain medications. Always tell your doctor or nurses if you are feeling pain, and inform them if the pain worsens or is severe.

What are the 4 stages of eating after bariatric surgery?

Stage 1 – Clear Liquids 

From the day after the surgery, you should go on a clear liquid diet for about 4 – 5 days. Do take note to drink slowly and avoid straws or chewing gum because they may lead to gas or bloating. Liquids that you may take during this period include: 

  • Diluted apple juice 
  • Lemon water 
  • Vegetable broth 
  • Gatorade 
  • Sugar-free citrus gelatin 
  • Pedialyte popsicles 
  • Diluted protein shakes (½ protein shake and ½ water) 

Stage 2 – Mushy liquids 

Foods that are mushy or have a yoghurt-like consistency are suitable for consumption after 4 – 5 days of clear liquids, lasting you about another 7 – 10 days. You may eat every 3 – 4 hours, and should be about ½ cup in size each time. Mushy liquids you may take during this stage include: 

  • Greek or nondairy yoghurt 
  • Oatmeal or cream of wheat 
  • Unsweetened applesauce 
  • Blended black beans, lentils or fat-free beans 
  • Pea soup, cream of mushroom soup etc. 
  • Mashed bananas 
  • Cottage cheese with baby food 

You may also want to mix protein with unsweetened almond milk or soy milk, but be sure to avoid cow’s milk.

Stage 3 – Soft and moist foods 

2 weeks after your surgery, you will be able to take softer foods for the next 2 weeks. These foods should be easily pulled apart with a fork, and should be about ½ cup in size per meal. However, you may stop eating as soon as you feel full. Examples of soft foods include:

  • Lean proteins like slow cooked chicken or pork 
  • Canned chicken or tuna 
  • Hard boiled eggs or poached eggs 
  • Baked potatoes, sweet potatoes or yams 
  • Stew 
  • Salmon or trout
  • Mashed lentils, chickpeas, tofu 
  • Soft, low-fat cheeses 
  • Soft fruits such as peaches and bananas 
  • Cooked or canned vegetables 

Stage 4 – Regular foods 

This starts about 6 weeks after surgery. You may want to start by adding 1 – 2 new foods per day, and avoid foods that can cause gas like broccoli, pepper, onions and spicy foods. Eat slowly and chew properly before swallowing. Every meal should have a size of about ¾ cups and should not exceed 1 cup.

Some foods you need to avoid are: 

  • Rice, pasta and bread 
  • Carbonated drinks 
  • Added sugars 
  • Oily or baked food 
  • Alcohol 

If you do not prepare your own meals, here are some tips on eating out after bariatric surgery in Singapore.

What can I do or not do after bariatric surgery?

Things to not do after bariatric surgery

After bariatric surgery, you will follow the diet as described above, so as to slowly work your way up from liquid to solid foods. Most patients will be able to take most foods, but there are some that would be best avoided. Here are some foods that are discouraged after bariatric surgery: 

  • Food with empty calories, like pastries, sweets, that provide little to no nutritional benefit 
  • Alcohol – alcohol absorption increases dramatically after surgery, so you would want to avoid it to prevent alcohol intoxication. 
  • Dry foods such as nuts or granola bars
  • Bread, rice and pasta – these do not have to be rejected completely, but avoid them or have them in very small quantities. I know this is difficult considering the Asian diet, but try opting for wholegrain options or consuming your refined carbs with plenty of water i.e. porridge
  • Fibrous fruits and vegetables – avoid fruits that will make digestion difficult
  • High-fat food such as bacon, butter, whole milk, hard cheeses – eating too much fat can make you nauseous or result in dumping syndrome
  • Sugary or highly-caffeinated drinks – these lead to dehydration
  • Tough meats

Bariatric patients must learn to chew their food slowly and thoroughly so that it is easier to digest. Start with small bites of food and avoid meats with fat or gristle. 

Also, patients are advised to avoid lifting heavy weights or doing strenuous activity, until the doctor says otherwise. 

Female bariatric patients should avoid pregnancy for 12 – 18 months after weight loss surgery, because it can affect vitamin and mineral levels in the body. If you have any deficiencies while pregnant, it could harm the baby. You could use contraception until it is safe to become pregnant after bariatric surgery

Things you can do after bariatric surgery:

Things you can do after bariatric surgery include activities like exercising, but start slow. You may wish to start by walking frequently. This is not just for the sake of weight loss, but can also help you to recover faster. Do check with your doctor before you begin any sort of vigorous exercise. Moderate exercise for 30 minutes every day is recommended.

Your nurses will teach you breathing techniques so that you can expand your lungs appropriately and prevent pneumonia and help improve circulation. 

You may drive after you have stopped the pain medication and are able to sit comfortably for long periods of time. 

Rest whenever necessary. Sleep is vital to your recovery and will help you feel better faster. 

Patients should follow up with their doctor every few months for the first year, followed by yearly visits to their bariatric specialist.

What does the recovery period look like after surgery?

Bariatric surgeries are now performed using minimally invasive techniques. This is good news because the incisions are small, and recovery time is drastically shortened with few complications. Most bariatric surgery patients stay in the hospital for about 2 or 3 days and are able to resume normal activities within 3 – 5 weeks. 

It is common to feel some fatigue and weakness after the surgery, due to the stress from an operation. You may feel soreness or belly pain for the first few days, and the doctor may prescribe some pain medication for you. 

People who undergo bariatric surgery for weight loss can expect about 40 – 60% weight loss. The exact value depends on your surgery and how well you keep to your diet post-op. Stick to your low-fat, low-sugar diet and you will be on your way to a healthier life. 

You may experience some mood changes, like being excited about weight loss or feeling overwhelmed or frustrated by the dietary changes you are forced to make. If you have any difficulties, speak to your doctor or a therapist.

What is the cost of bariatric surgery in Singapore?

The cost of bariatric surgery in Singapore can vary from up $25000 – $28000 if you are a private patient, to $8000 – $10000 for those who are subsidised.

The cost of bariatric surgery depends on the type of surgery, the complexity of the surgery, the infrastructure required and other medical conditions that need to be factored in, and also the medication costs.

What are the risks of bariatric surgery? 

Every surgery comes with its risks and potential complications. However, bariatric surgery is known to be a relatively safe surgical procedure. The complications after bariatric surgery includes:

  • Bowel obstruction
  • Dumping syndrome that causes nausea, vomiting, sweating, dizziness or diarrhoea 
  • Gallstones 
  • Hernias where an internal organ protrudes outwards 
  • Vitamin and other nutrient deficiencies
  • Ulcers 
  • Saggy skin from extreme weight loss


If you still aren’t sure if bariatric surgery is right for you, discuss with your doctor the possible options and weigh the pros and cons before deciding. Feel free to try other methods that do not require surgery, such as going on a low-calorie diet or incorporating exercise into your lifestyle. We understand the pain of a weight loss journey, and are always here to help you. If you would like more information, visit our website or WhatsApp us at +65 8218 7799.


  1. Wolfe, B. M., Kvach, E., & Eckel, R. H. (2016). Treatment of Obesity: Weight Loss and Bariatric Surgery. Circulation research, 118(11), 1844–1855.
  2. Pories W. J. (2008). Bariatric surgery: risks and rewards. The Journal of clinical endocrinology and metabolism, 93(11 Suppl 1), S89–S96. 

This article was written and medically reviewed by Dr. Ganesh Ramalingam, M.D.