Weight-loss (bariatric) surgery changes your daily life and eating habits a great deal. To help your body adjust and to avoid possible complications of the operation, there are some rules to follow before surgery. The most important is the pre-operative diet, which helps you cut down on calories.
Why diet before the operation?
If you have already tried many diets, the word "diet" may not sound very appealing. The diet before surgery, which usually starts about two weeks before the operation, has a different aim and a different make-up. You can also think of it as a trial run for a healthier way of living. Some patients tend to eat more during this time, thinking "I'm having the operation anyway". To avoid this, support from a dietitian is important.
What does the diet involve?
The diet is tailored to you. It is usually planned so that you eat about 100 g of carbohydrate a day. It is low in fat and high in protein, and provides about 800 to 1000 kcal a day. As well as carbohydrate and protein, it includes vegetables, fruit and dairy products. Protein helps support and protect your muscle tissue. This means your body can burn fat for energy instead of muscle.
Fatty liver and abdominal fat
With marked obesity, the liver becomes enlarged because it stores excess fat and sugar. Almost everyone living with obesity has some degree of fatty liver. The diet helps to shrink the liver and stop it pressing on the stomach. People with obesity also have more fat inside the abdomen. This can make keyhole (laparoscopic) surgery harder, even though this approach has several advantages for both patient and surgeon.
With the pre-operative diet, the liver becomes healthier, your weight goes down and obesity-related conditions can be better controlled. Conditions such as diabetes, high blood pressure and high cholesterol can increase the risks of surgery.
Five reasons for the diet before surgery
- Losing weight: losing some weight before the operation is one of the aims of preparation.
- Keeping your muscle: when you lose weight quickly, you can also lose muscle quickly. That is why getting enough protein is the most important part of the diet. Your dietitian will set out in your personal eating plan how much protein you need.
- Shrinking the liver: as you gain weight, your liver gets bigger and fattier. The stomach lies beneath the liver. If the liver is very enlarged, it can be harder for the surgeon to reach the stomach.
- Building awareness: changing how you eat before surgery shows you how you will eat after it. This awareness helps you keep the weight off after the operation. Some people regain weight after bariatric surgery; without awareness of your own eating habits, discipline and self-control are harder.
- Adjusting: cravings for sugary foods arise mainly because the body is used to getting them regularly. When you cut down on carbohydrates, the cravings fade over time. People are good at adapting to new habits.
An empty stomach for the operation
The diet before surgery also helps make sure your stomach is "clean" during the operation. Solid food left in the stomach increases the risk of complications. It can also raise the number of bacteria in the stomach and so lead to infection.
Practical tips
- Cut out saturated fats as far as possible, for example from full-fat dairy products, meat and fried food.
- Avoid foods rich in carbohydrate, such as sugar, pasta, potatoes and bread.
- Spread what you eat and drink evenly across the day's meals.
- Drink at least 2 litres of water a day. Milk, juice, tea and coffee do not replace water. When counting calories, include every drink other than water.
- Avoid alcohol and smoking.
- Take vitamin and mineral supplements every day.
- Stay active.
