Research

Mixed

Very Low-Calorie Ketogenic Diets (VLCKD) and Protein-Sparing Modified Fasting (PSMF) produce rapid, significant weight loss and preserve lean mass in obese patients, but require strict medical supervision due to risks of gallbladder issues and electrolyte imbalance.

If you have severe obesity and comorbidities, VLCKD or PSMF can help you lose weight faster than standard diets while preserving muscle. However, these are not DIY diets; they require strict medical supervision, supplementation, and monitoring to avoid side effects like gallstones or electrolyte imbalances.

ModerateSupportsMEDIUM confidence
VLCKD... achieves the desired weight in less time than conventional low-calorie diets. Usually, an average weight loss of 1–1.5 kg per week is achieved... lean body mass was well-preserved... PSMF... allows excellent results to be obtained even with long-term weight reduction maintenance... it is essential that a modified fasting protocol... can be with adequate vitamin, hydroelectrolytic and fiber (20 g/day) and followed under close specialist medical supervision.
Samir Giuseppe Sukkar et al. · Frontiers in Nutrition · 2021

Why this rating

Based on narrative review of multiple studies, including meta-analyses and clinical trials, but lacks large-scale long-term RCTs for all variants.

Source

A Clinical Perspective of Low Carbohydrate Ketogenic Diets: A Narrative Review

Samir Giuseppe Sukkar et al. · Frontiers in Nutrition · 2021

DOI 10.3389/fnut.2021.642628

narrative_reviewCited 56×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

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