A Dietitian's Role in Bariatric Surgery and Nutrition

Obesity is a common yet costly disease because it increases a person's risk of chronic conditions, such as heart disease and cancer. It may also lead to severe complications if an obese patient gets infected with COVID-19.

In 2020, the World Health Organisation reported that 39% of adults worldwide were overweight, with 13% of them obese. In Singapore, the obesity rates among adult Singaporeans has remained stable since 2013. However, obesity rates have been steadily rising in children (aged 6 to 18 years): from 11% in 2013 to 13% in 2017, according to data published in the 2017 National Population Health Survey.

What is bariatric surgery, and when is it necessary?

Bariatric surgery is recommended only when obese patients are unable to lose weight through conservative measures such as dieting and exercise.

In Singapore, it is medically recommended for patients with a BMI more than 37.5 and who do not suffer from any associated medical conditions. It is also advised for patients with a BMI over 32.5 and who suffer from obesity-related health issues, such as diabetes, high blood pressure, high cholesterol (hyperlipidaemia) or obstructive sleep apnoea.

To describe it simply, bariatric surgery treats obesity by modifying the stomach and intestines. The operation may make the stomach smaller and may also involve making changes to the 'flow' of a patient's digestive tract, which may see food bypass a portion of the intestine. This leads to less food intake, changes how the body absorbs nutrients, and results in a patient being less hungry and feeling full more easily. It is a major procedure that is usually permanent, and requires long-term adjustment to a new diet and lifestyle.

What happens after bariatric surgery?

Bariatric surgery is only one point in the care journey for an obese patient. A successful long-term outcome of bariatric surgery is dependent on the patient's understanding of the role of bariatric surgery in weight management and his or her commitment to a lifetime of dietary and lifestyle changes.

The role of a dietitian

A dietitian plays an important role in every aspect of care during the patient's treatment journey through bariatric surgery. This includes preoperative assessment of the patient to long-term follow up, evaluation, and monitoring.

A significant component of weight loss surgery is diet and lifestyle changes prior to surgery. A dietitian will first perform a nutrition assessment and educate patients on the importance of getting nutrition from the right sources as they get ready for their weight loss surgery.

This assessment includes:

• Finding out the patient's weight history and previous weight loss strategies
• Deciphering factors affecting weight issues such as work, social, and medical issues
• Understanding his or her dietary patterns, nutritional and vitamin supplement use
• Levels of physical activity; possible limitations
• Readiness and motivation to make long-term lifestyle changes

A personalised approach

Following this assessment, a dietitian will work closely with the patient to tailor their diet and lifestyle to help achieve a successful post-operative weight loss and maintenance. These recommendations may include working out a diet plan with patients to incorporate meal-replacement formulas so as to reduce their intake of high fat and sugary foods.

This is especially important in the 2 weeks leading up to the operation. The dietitian will also recommend healthy snack choices and suggest dietary supplements as indicated by the patient's preoperative nutritional and laboratory tests as well as medical evaluations. The duration of this process will vary depending on a patient's readiness. It may span weeks to months.

Nutrition goals

Following bariatric surgery, the nutritional goals for each patient are to achieve a substantial calorie deficit (to enable weight loss) while maintaining an adequate intake of essential macro- and micro-nutrients. Protein is one such essential macronutrient, as having an adequate amount of it is important in the post-surgery phase to ensure that a patient is able to maintain muscle mass while losing weight.

Both malabsorptive and restrictive bariatric procedures can increase a patient's risk of protein malnutrition because they may reduce the body's ability to absorb food and nutrients on top of a substantially reduced food intake. Other examples of common micronutrient deficiencies include a lack of iron, calcium, and vitamins D and B12.

In the early post-operative phase (0 – 3 months post-surgery), the dietitian will lead the patient through the post-operative diet progression, monitor and help prevent early nutrition complications such as vomiting, diarrhoea and dehydration. This also involves helping the patient implement a vitamin and mineral supplementation regimen.

In the remaining months of the first year, the dietitian will guide the patient in essential lifestyle and behaviour changes to support continuing weight loss. An example of a healthy, lifelong diet post-surgery will include a strong focus on nutrient-dense and minimally-processed food. This is where a dietitian will guide the patient through structured meal and snack (if needed) plans, and also monitor other aspects such as the patient's eating speed and portion sizes to promote weight loss and sustain weight maintenance.

To find out more about the various nutrition and dietetic services or discover how nutrition can help make a difference to your personal wellness, do request for a doctor's referral to see a dietitian and make an appointment online or call +65 6470 3422 / +65 6470 5662 to schedule an appointment.