Weight-loss & macronutrient diets
Very-low-energy diet (VLED)
Provides fewer than 800 calories per day, normally via nutritionally formulated products, for a limited period under clinical supervision.
What people typically eat
Formula shakes, soups or bars supplying all meals, plus water and prescribed micronutrients; conventional food is reintroduced gradually afterwards.
What is restricted
Almost all conventional food during the active phase.
Why people try it
Rapid, substantial weight loss before surgery, or diabetes remission in specialist programmes.
Realistic advantages
- The fastest dietary weight loss available
- Can produce type 2 diabetes remission in a substantial minority in trials
- Formulated products prevent the worst nutrient gaps
Realistic disadvantages
- Significant side effects: fatigue, dizziness, constipation, hair thinning
- High regain rates if the re-feeding and maintenance phase is skipped
- Requires medical monitoring, it is a treatment, not a lifestyle choice
Strength of evidence
Moderate evidence
Strong short-term evidence in supervised settings; long-term outcomes depend entirely on the maintenance plan.
Likely cost and difficulty
Moderate cost (products plus clinical follow-up); very high difficulty.
Nutritional risks
Gallstones, electrolyte disturbance, muscle loss and refeeding problems, the reasons supervision is mandatory.
Who should avoid it
Anyone not under clinical care for it; absolutely not for pregnancy, adolescence, eating disorders or significant heart, liver or kidney disease without specialist oversight.
Is professional supervision advisable?
Essential. NICE guidance treats VLEDs as a clinical intervention, not self-help.
References
Written by the Slimr editorial team. How we review diets.
