Fasting After a Bariatric Surgery

During the Holy Month of Ramadan, the requirement to observe a total fast poses a challenge to the health of people who have undergone bariatric surgery. A patient who has undergone bariatric surgery can experience health complications due to fasting. It is important to understand the kind of risks one is exposed to, before he/she decides to fast during Ramadan.


Gastric bypass, sleeve gastrectomy and other weight-loss surgeries are collectively known as ‘bariatric surgery’. These surgeries involve making changes to the digestive system to enable weight loss and achieve a healthy body weight. Bariatric surgery is usually carried out when diet and exercise do not produce results or when a person has serious health problems because of their weight. Increasingly, bariatric surgery is performed for the correction of morbid obesity, especially if a person has co-morbidities like diabetes.

Some procedures limit how much a person can eat, while some procedures work by reducing the body's ability to absorb nutrients. Bariatric surgery is a life-saving option for many people and can help to reduce the risk of life-threatening complications associated with obesity. Patients who have undergone bariatric surgery including gastric banding, sleeve gastrectomy and gastric bypass are required to take special measures to avoid health risks.


Patients who have undergone bariatric surgery need to follow certain medical recommendations. Failure to do so can affect the healing process and cause post-operative complications among other health risks. Inadequate and unbalanced nutrition, malnutrition, particularly dehydration is undesirable in the first period after bariatric surgery. A total fast for many hours can expose one to numerous risks.

Poor nutritional intake and overeating risk: After bariatric surgery, a patient is usually advised to:

  • Eat small, frequent meals.
  • Eat slowly and chew thoroughly.
  • Separate eating and drinking
  • Stop eating when feeling full or satisfied.

If a person is fasting for long periods during Ramadan, it can lead to the desire to consume larger quantities at a faster pace upon breaking the fast. This can result in abdominal discomfort, nausea and vomiting leading to dehydration, malnutrition and vitamin and mineral deficiencies.

Dehydration: A minimum of 1.5-2 liters of fluids throughout the day is essential, following bariatric surgery to keep hydrated and help prevent constipation. One should not drink quickly, drink large amounts in one sitting or eat and drink together. These restrictions, combined with long hours of Ramadan fasting (especially during summer) can increase the risk of dehydration.

Vitamin and mineral deficiencies: After bariatric surgery, patients are recommended to take regular timely vitamins and minerals. One of the challenges during Ramadan is that the reduced stomach capacity may make it difficult to have the recommended vitamins and minerals in a short time frame and space them adequately, which may result in some deficiencies. The small stomach volume may also pose further difficulty with fitting in nutritional supplements and medications around mealtimes. It is not recommended for a person to stop taking these vitamins/minerals during Ramadan, which is why fasting is a challenge for people who have had recent bariatric surgery.

Hypoglycaemia: The risk of hypoglycemia (low blood sugar) is increased when fasting for a significant period (i.e., more than 10 hours). For example, if a person does not eat between suhoor and iftar, they may develop hypoglycemia if they are not healthy.

For these reasons, it is important that patients who have undergone bariatric surgery do not stay hungry and thirsty for extended periods of time for the first 12-18 months. It is not medically recommended for patients to fast for the first 12-18 months after bariatric surgery to prevent malnutrition and medical complications.

When can a person start fasting?

The risk of post-prandial (after eating a meal) is reduced after the first 12-18 months, and patients who make a satisfactory recovery and are in good health can observe Ramadan fast. However, it may be recommended that they still take some fluids throughout the day. This applies especially for people who undergo malabsorptive procedures such as gastric bypass. They must be informed of the importance of continuing vital supplements like iron, calcium, vitamin D or other multivitamins throughout the day.

Diet and lifestyle tips for bariatric surgery patients during Ramadan

  • Break the fast with around 200-250 ml of water. You can also opt for soup and stew or other food items with plenty of water. Breaking the fast with 1-2 dried dates is very helpful in raising blood glucose levels after fasting for a long time.
  • Aim for a balanced meal. Cover half of the plate with protein, and the remaining two quarters with vegetables and carbohydrates. Start with eating protein rich foods first, then vegetables and lastly carbohydrates.
  • Avoid foods high in fat/sugar such as traditional desserts or deep-fried meals to avoid symptoms of dumping syndrome. Patients should base their meals on complex carbohydrates that give long-term energy, along with high-quality proteins. This involves consuming lentils, chickpeas, beans, rice, eggs, lean meats, fish and whole grains.
  • Avoid sleeping immediately after eating as this can result in acid reflux, and abdominal discomfort.
  • Have a minimum of 1.5 liters of fluids per day.
  • You do not need to stop all physical activity during Ramadan. Continue your routine exercise but reduce its intensity. You also might need to reschedule your exercise time.  

People who are physically incapable of fasting due to health reasons can exempt themselves from fasting for their well-being. It is urged that people who have recently undergone bariatric surgery heed medical advice carefully, and do not fast if they are advised against it. It is important to let the body make a strong recovery from the surgery to enjoy an improved quality of life and continue Ramadan fasting in the future.

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