Very low energy diets

What is very low energy diets (VLEDs)?

A very low energy diet (VLEDs) has a very low total daily energy intake target.

On this diet, people are guided to consume between 2500–4000kJ per day.

Formulated Meal Replacements

This is usually achieved using Formulated Meal Replacements (FMRs) which are designed to be a nutritionally complete replacement for all meals in a day when consumed as directed.

They are most commonly sold in shake or bar form at a pharmacy. In some countries you can only purchase them with a doctor’s prescription.

In addition to the FMRs, it is also usually recommended to consume 2 cups of vegetables to help boost fibre and vitamin intakes, and 20g (1tbsp) of oil each day to help keep the gallbladder contracting.

VLEDs lead to rapid weight loss which is why it is recommended that they only be used under medical supervision by a doctor and/or dietitian.

The advantages of VLEDs are that they are useful for when rapid weight loss is required e.g. prior to surgery for patients with obesity.

They help lose fat from the liver and reduce its size, making intestinal surgery less risky.

The disadvantages of VLEDs are that they are hard to adhere to due to their large and severe energy restriction. Following a VLED usually gets easier after two to three days once the body’s stores of glycogen are used up and the body starts to burn more fat.


Once this happens, ketones are produced as a byproduct of fat metabolism and they have been shown to reduce hunger.

People following a VLED may also experience some side-effects including light-headedness, fatigue, headaches, bad breath, and constipation.

There is also an increased risk of gall bladder disease, liver inflammation, and gout. They should only be used under medical supervision.

Very low energy diets

A very low energy diet consisting of 3 meal replacement shakes and 2 cups of vegetables. 
A tablespoon (20g) of oil is also recommended.

A nutrition breakdown of this intake:

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