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What is a VLCD? What you need to know about this diet

Here's what kind of weight loss you can expect with a VLCD.

Written by
Lucinda Starr
Medically reviewed by
Dr Vincent Mok
Last updated
April 29, 2024
min read
What is a VLCD? What you need to know about this diet
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If you're working with a doctor to shed those stubborn kilos, you might hear about a thing called a very low calorie diet (or VLCD for short).

It's a type of strict low calorie diet that can be recommended for people who are classified as obese or severely obese, as well as people managing diabetes.

While very low calorie diets can be effective in supporting short term weight loss, there are important drawbacks to consider, too. Along with being very restrictive, a VLCD program might not deliver sustainable results that you can maintain over the long term.

To help you understand whether a very low calorie diet is right for you, let's run you through what this low calorie diet is all about, what kind of weight loss you can expect and how this diet compares to a low energy diet program.

What is a VLCD?

Let's start with the question that's likely on the top of your mind: what is a very low calorie diet?

In a nutshell, a VLCD program is a clinically supervised weight loss plan that involves restricting the number of calories you consume for a specific period of time. Typically, it involves eating 800 calories or less as a way to speed up the weight loss process.

A VLCD might be recommended if you're classified as an obese or severely obese patient, or if you're navigating another condition (such as diabetes) at the same time.

This tool is often prescribed if you record a BMI (body mass index) over 30 or 40 and can offer rapid weight loss over a set period of time (usually programs run for up to 12 weeks).

During a very low calorie diet, you'll be supervised by a doctor or GP who will set out what you can and can't have as part of your diet.

How do very low calorie diets work?

Typically, a very low calorie diet involves swapping regular food for low-calorie products like shakes, soups, bars and other diet supplements. These products will provide all the essential vitamins and nutrients you need, while still being incredibly low in calories and helping you lower your energy intake.

The principles behind very low calorie diets are simple: the less you eat, the more weight you're expected to lose.

Each kind of VLCD is slightly different in what kinds of foods and products you'll be able to consume. Some require you to switch every meal out for a shake or bar, while other versions of this low calorie diet still allow you to eat low calorie food like vegetables.

Because VLCD programs are considered to be quite restrictive, it's important to speak with your GP first to ensure you're managing your diet in a safe way. Without medical supervision, you may not be providing your body with the right nutrients and essential fatty acids it needs throughout your weight loss journey.

However, with the right support in place, you can use these meal replacements as a way to speed up your weight loss journey. This combination of meal replacement drinks and low-calorie diets has proven to be effective when researched.

Take this example from a study back in 2008: a 59-year-old severely obese man (who was also navigating type 2 diabetes) was put on a very low calorie diet program for 12 months. During this time, he was under close medical supervision and recorded an impressive 43 per cent weight loss.

It's important to note that staying on a VLCD is often not recommended — it's usually undertaken for a period of 12 weeks for rapid weight loss.

In order to lose weight and keep this weight off, this patient needed to swap at least one meal a day out for a VLCD program shake. This study reported that simple lifestyle changes alone weren't likely going to be effective enough to ensure effective weight maintenance.

What are the benefits of following very low calorie diets?

Clearly, very low calorie diets are a challenging and demanding way to encourage weight loss. So, why would someone consider reducing their calorie intake to such an extreme level?

For people who are navigating obesity and looking for a rapid weight loss solution, VLCDs can offer large initial weight loss in a short space of time. That's because a very low calorie diet totally transforms your diet and replaces some (if not all) meals with protein-rich shakes and diet products.

Rather than worrying about portion size or your level of carbohydrate intake, very low calorie diets take the guesswork out of mealtime. This can make it easier and more convenient to stick to the low-calorie limits and see a greater initial weight loss in a short space of time.

Plus, it's a less invasive approach than other common weight-loss strategies. The most common alternative to the dietary management of obesity has been bariatric surgery, which constricts the stomach and how much food can be consumed.

In Australia, some of the most common types of bariatric surgery include lap band surgery, gastric bypass or banding and gastric sleeve surgery. All of these options use a keyhole procedure and a pouch or adjustable ring to lower a patient's food intake.

However, this kind of surgery can come with complications such as infection and is much more expensive than the calorie restriction used in a VLCD program.

Expected rate of weight loss using the VLCD

In general terms, a VLCD is shown to be very effective in supporting rapid weight loss, at least in the short term. But the key to success is to ensure you're working with a medical professional who is able to monitor your weight loss and ensure you're not jeopardising your health and wellbeing in the process.

While the results will differ from person to person, studies have shown that obese people following very low calorie diets tend to see an average weight loss of 1.5 to 2.5 kilos per week.

Some studies have shown that using a total food replacement program can be more effective in driving faster weight loss, in comparison to a food-based VLCD program.

What is a VLED?

Very low calorie diet (VLCD) and very low energy diet (VLED) are interchangeable terms and refer to diets with less than 800 calories per day.

A very low energy diet is the same as a very low calorie diet and both usually require the replacement of all meals with shakes or bars (supplemented with some dietary fibre and a bit of olive oil to keep the gallbladder contracting and lower the risk of gallstones).

When undertaking VLEDs and VLCDs, you must be medically supervised as there is a risk of potentially serious side effects and not all patients are suitable due to pre-existing health issues.

Often VLEDs and VLCDs involve consuming low amounts of carbohydrates and high amounts of protein to induce ketosis in order to promote using fat stores as energy (instead of sugars and glucose). This is usually continued for 12 weeks to achieve rapid weight loss.

What are the downsides of a VLCD?

Following a very low calorie diet (VLCD) can come with a set of challenges. From hunger pains to the question of whether weight regain is inevitable, there are a few downsides to consider before chatting to your GP about this kind of program.

Some of the key things to consider about a VLCD include:

  • Side effects like headaches, weakness, fatigue, nausea, vomiting, constipation and low blood sugar can be common in the first four to 16 weeks.
  • Medical supervision is needed to ensure you're meeting weekly weight losses and meeting the nutritional status your body needs to thrive.
  • Weight regain can be common, especially if long term weight maintenance strategies aren't put in place to support long term healthy eating habits.
  • Gallstones can be common in people who are obese and experience a period of rapid weight loss, which is why medication might be needed to prevent this from happening.

What's the alternative?

Another option is the low calorie diet, where you consume 1,000 to 1,500 calories per day, which is substantially more than a VLCD. This diet involves replacing one or two meals with shakes or bars and can be used after a VLED or VLCD to slowly transition back to meals with whole foods.

You don't have to follow a VLCD in order to lose weight. This is why Pilot's Weight Reset Shakes were created — to offer nutritious meal replacement shakes that keep you feeling satisfied while also losing weight.

When used in conjunction with a low calorie diet and medical or dietician supervision, you can make a real difference to how you feel. On the Rapid weight loss plan, which includes two shakes a day, a weekly weight loss of two kilos is expected.

Another option is the Steady weight loss plan. The combination of one meal replacement shake per day and a low-calorie diet can help you lose four per cent of your body weight in 12 weeks.

The Weight Reset Shakes are low in carbs and calories but are packed with 20 vitamins and minerals. In fact, each shake contains 40 per cent of your daily vitamin needs for immunity and overall health.

It’s recommended that you use this in consultation with your GP and dietician to make sure they’re suitable for you as well as discuss potential precautions.

They'll be able to guide you through your options, assess whether this kind of diet is a good approach and monitor your progress through this weight loss program.

Photo credit: Getty Images

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