Nicola Drabble (R.D) and Renata Wilson (R.D)


Twelve weeks prior to surgery, extensive preoperative dietary education is given which includes dietary information that addresses pre- and post-operative diet stages, texture progression, and the importance of protein, hydration, and vitamin supplementation. Patients who are not willing to make these changes, or who do not seem to understand these requirements, may not be ready to undergo surgery. 


A balanced, low energy eating plan is commenced to achieve initial weight loss. A preoperative weight loss of 5% to 10% is aimed for, specifically in patients with a BMI greater than 50 kg/m2, and those who suffer with obesity-related comorbidities. Weight loss before surgery reduces preoperative morbidity and the risk of perioperative complications. It also has the added benefit of reducing the size of an enlarged fat-infiltrated liver. 


During this pre-operative phase, the patient is encouraged to consume a diet which is low in fat and refined carbohydrates (sugars). This eating plan can also be used after bariatric surgery. It forms the basis of good eating habits and successful weight loss as well as to reduce post operative dietary related complications such as diarrhea and dumping syndrome. The dumping syndrome occurs when too much sugar or fat is eaten and the contents of the stomach are transported or ‘dumped’ into the small intestine too rapidly, causing symptoms such as sweating, dizziness, faintness, rapid weak pulse, diarrhea and hypotension (low blood pressure). 


Patients are encouraged to prepare meals so that 50% of the plate is filled with vegetables, 25% with lean protein (meat, fish, chicken, eggs, pulses and fat free dairy products), and the remaining 25% with complex carbohydrates (whole wheat breads, pasta, rice, potatoes and cereals). Patients will be guided to add more fruits, vegetables, whole grains, and beans into meals, as these foods have a high fiber and water content which will lengthen satiety and are generally the lowest in calories. 


Patients who are required to follow a partial meal replacement diet, should choose meal replacements that have a balance of macronutrients, provide 180 to 200 calories per meal and 15 to 20 g of protein, and are low in sugar (≤16 g of sugar per 200 calories). The dietitian will advise on this. Portion-controlled meal replacements provide a release from complex dieting and produce successful, gradual weight loss. All patients should be encouraged to avoid last-minute binging before their surgery. 


Any existing nutritional deficiencies are addressed pre-operatively. Calcium, potassium, iron, protein, albumin and Vitamin D are nutrients at risk. Hyperlipidaemia, raised glucose levels and non-alcoholic steato-hepatitis can also be improved with an adapted diet and lifestyle. In general, the aim is to establish better eating behaviour by encouraging the patient to consume 4 small meals per day, chew slowly and sip water in-between meals. 

Carbonated drinks, coffee and alcohol should be avoided preoperatively, and 3 months post-operatively.

eating plans



≈ 40% of total caloric intake

The total should not be less than 130 g/day

A minimum of 20-35 g of fiber per day


≈30% of total caloric intake


≈ 30% of total caloric intake

Choose mono- and polyunsaturated fats: olive oil, canola oil, nuts/seeds, fish, particularly those high in omega-3 fatty acids (eg, salmon, herring, trout, sardines, fresh tuna) 2 times/wk

BEFORE SURGERY - 2 Weeks prior to surgery date (14 days)

To be followed for 7 days:

A SOFT-LIGHT diet - consists of soft foods which as easy to mash with a fork – i.e. no skins/ pips and food must be cooked appropriately.

This is to start relaxing the digestive tract in preparation for surgery.

7 Days prior to surgery date:

A FULL LIQUID diet – consists of smoothies, soups and protein supplements.

To relax the digestive tract and get rid of residue.

DURING – In hospital 

STAGE I - IN-HOSPITAL: Immediately Post-surgery

Stage 1 is brief and completed in the hospital.

Clear liquids only:

Very thin clear liquids with water sipped in-between to prevent dehydration – consists of water, consommé, iced tea lite, and diabetic jelly.

Meal Pattern:

Slowly sip fluids throughout the day, aiming for 100ml clear liquids and 70 ml water per waking hour.

After surgery

The objectives of post-operative nutrition are to maintain adequate hydration and nutrition status; support homeostasis of bodily functions; promote wound healing; preserve lean muscle mass; facilitate safe and sustained weight loss; and nurture a healthier lifestyle. These goals are achieved through a multiphase dietary progression. 


Full Liquids:

Soups, Smoothies, Protein Supplements

Minimum 80g protein/ day

Total amount of fluid is 2.5L (supplements included)

1 L of full liquids, plus 1.5 L fluids

Stage II provides high quality protein, low-fat and low-sugar liquidized foods.

During stage II, the patient is dependent on liquid protein supplements or meal replacements as the primary source of nutrition eg Future Life High Protein.

In 2% of patients there is continuous nausea that may not be diet related. A physician must be consulted to assist with nausea resolution.

In some cases, approximately 15% (conservative estimate) of patients exhibit lactose intolerance. In this event, use lactose free milk and dairy products.

Meal Pattern:

Slowly sip fluids throughout the day, aiming for 100ml of full liquids and 70 ml water per waking hour.


Puree/ Sloppy Diet:

Protein requirements: 1.0-1.5 g protein /kg of adjusted body weight

Fluids 2 L per day

Stage III consists of pureed and ground foods which are very moist and runny

Diet must consist of 50 % protein (to be eaten first) and must be low in fat and sugar

Meal Pattern:

6 small meals per day consisting of 60–90ml (4 – 6 tbsp) of pureed food


Soft and Light Diet: 

Stage IV consists of soft foods which as easy to mash with a fork – i.e. no skins/ pips and food must be cooked appropriately.

It gradually reintroduces the system to solid food.

Diet must consist of 50 % protein (to be eaten first) and must be low in fat and sugar.

Meal Pattern:

4 small meals per day consisting of ½ cup - ¾ cup of soft food.


Solid Foods:

All foods can now be included in the diet.

Diet must consist of 50 % protein (to be eaten first) and must be low in fat and sugar.

Meal Pattern:

4 meals per day consisting of 1 - 1½ cups of food of regular consistency and firmer texture as tolerated.

The post-bariatric surgery diet progression should be followed carefully. The rate at which the patients progress from one food consistency to another will vary. Generally, patients should be able to tolerate foods of regular consistency with firmer texture 3 months after operation.


Waterfall City Hospital

Magwa Cres & Mac Mac Avenue, Vorna Valley, Midrand, 1682


Linda Crystal

Tel: +27 11 304 7821

Isobel Vosloo

Tel: +27 11 304 7975

Fax: +27 11 304 7961

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