Very-low-calorie ketogenic diets improve weight, metabolic parameters in obese patients

Very-low-calorie ketogenic diets (VLCKDs) over a 45-day period are associated with substantial weight loss and significant improvements in metabolic parameters, a study has shown.

Whey- or vegetable protein-based VLCKDs show a safer profile and a more healthful microbiota composition as compared with those containing animal proteins. In addition, VLCKDs incorporating whey protein appear to be more effective in maintaining muscle performance.

“We compared the efficacy, safety, and effect of 45-day isocaloric VLCKDs … on the microbiota in patients with obesity and insulin resistance to test the hypothesis that protein source may modulate the response to VLCKD interventions,” the investigators said.

Forty-eight obese patients (aged 56.2±6.1 years; 29 females; body mass index [BMI], 35.9±4.1 kg/m²; homeostatic model assessment [HOMA] index ≥2.5) were randomized to three 45-day isocaloric VLCKD regimens (≤800 kcal/day) containing whey, plant, or animal protein.

The investigators evaluated the following factors: anthropometric indexes; blood and urine chemistry, including parameters of kidney, liver, glucose, and lipid metabolism; body composition; muscle strength; and taxonomic composition of the gut microbiome. They also recorded adverse events.

VLCKDs significantly reduced body weight, blood pressure, BMI, waist circumference, insulin, HOMA index, and total and low-density lipoprotein cholesterol in all patients. Improvement in muscle strength was more pronounced in those who consumed whey protein. However, renal function markers slightly worsened in patients who consumed animal protein.

After the consumption of VLCKDs, the relative abundance of Firmicutes decreased and of Bacteroidetes increased. Such trend was less pronounced in patients who consumed animal protein.