At Diet Doctor, we've been writing about the benefits of ketogenic diets for weight loss and health for years.
Now a large review of clinical trials and cohort studies has concluded that very-low-calorie, ketogenic diets (VLCKDs) are both safe and effective for achieving weight loss in people who are overweight or obese:
Efficacy and safety of very low calorie ketogenic diet (VLCKD) in patients with overweight and obesity: A systematic review and meta-analysisOf the 12 studies included in the review, 4 were randomized, controlled trials (RCTs). In all studies, overweight and obese adults reported consuming fewer than 800 calories and 50 grams of carbs per day for several weeks. This strict phase was followed by a gradual increase in calorie and carb intake as part of a multi-phase intervention.
In the initial phase, weight loss averaged 22 pounds (10 kg) in studies where the ketogenic diet was consumed for less than 4 weeks, and 33 pounds (15 kg) in studies where the ketogenic diet period lasted 4-12 weeks. In addition, study participants experienced beneficial changes in several health markers, including lower triglycerides, blood pressure, and liver enzymes.
Only three studies had follow-up periods lasting two or more years. Interestingly, the researchers of those studies reported that many people were able to maintain most of the weight they'd lost during the initial phase of the VLCKD, even though their calorie and carb intake had increased over time.
At Diet Doctor, we feel that deliberate, drastic calorie restriction isn't necessary for weight loss on a ketogenic diet. After all, high-quality evidence has repeatedly demonstrated that ketogenic diets reduce appetite, leading to a spontaneous decrease in calorie intake. However, we're encouraged that researchers are studying VLCKDs and showing that they can be safely used to "jump start" weight loss, bridging to a nutrient-dense, low-carbohydrate lifestyle that can be sustained long term.