Weighing up the benefits of very low calorie diets

3 minute read

Very low-calorie diets are now considered a standard evidence-based therapy for patients with obesity or overweight, but they have to be prescribed safely

Very low-calorie diets (VLCDs) have existed for decades and shown safe and rapid weight loss in obese and overweight patients, but some GPs are still hesitant to prescribe them.

Professor John Dixon, GP academic and former rural GP, presenting at the at the Healthed Annual Women’s and Children’s Health Update at the weekend, said he hoped more health professionals would learn about very low-calorie diets, which were becoming a commonplace treatment for obesity.

VLCDs require patients to consume low carbohydrate foods, adding to a total of no more than 800 calories a day, to induce ketosis in the body.

Studies show the body takes about three days to become ketogenic, at which point hunger is suppressed and fat burning starts to occur.

Professor Dixon said patients who were suitable for VLCDs were those with a BMI >30 or a BMI >27 when comorbidities were present.

“Ketosis will continue to provide energy for the brain and heart, and they [the diets] are not dangerous,” Professor Dixon said.

“We are not talking about diabetic ketoacidosis or acidosis we see with illness. But, you will be able to smell it on the breath and you can find it in urine of patients.”

Often the easiest way for obese and overweight patients to start a VLCD requires meal replacements which can be purchased from pharmacies in the form of shakes or bars.

To begin the diet for rapid weight loss it’s recommended patients consume three meal replacement products a day for three or four days before slowly replacing the meal replacements with low-calorie, high protein foods.

“Patients will be very hungry and if they need help getting through the first few days you might want to consider medication to help suppress appetite,” Professor Dixon said.

“The ideal pharmacotherapy is phentermine because it works the day it is taken, meaning if the patient only needs it for three or four days then they will only need a few tablets to get them into ketosis.”

But Professor Dixon said along with eating high-quality proteins, salads and low-starch vegetables, patients should have approximately one teaspoon of olive oil a day to promote healthy gallbladder activity.

Some common side-effects which patients might complain about may include dry mouth, constipation, headaches, dizziness, fatigue and orthostatic hypotension, but these symptoms generally subside after two weeks.

As reported in The Medical Republic last year, many of these low calorie diets are contraindicated for pregnant women, older age and patients on medication such as insulin, gliclazide or warfarin.

Professor Dixon said patient success on these VLCDs was facilitated by GPs, dieticians and their teams being positive and providing support.

“Giving initial support and meal replacements are an essential part of these VLCD programs but they won’t suit everyone, just like pharmacotherapy doesn’t suit everyone and neither does surgery, but we now know this is one model of care which works,” he said.

“I hope that meal replacements, pharmacotherapy and surgery are seen as some of the essential tools for managing weight for your patients.”

In other developments, Wednesday will mark the first World Obesity Day.

One of the goals of the day is to reduce the stigma associated with weight which often prevents patients from being able to access affordable and evidence-based treatments.


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