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Pre-operative Very Low Calorie Ketogenic Diet (VLCKD) vs. Very Low Calorie Diet (VLCD): Surgical Impact

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Pre-operative diet may play an important role as far as patients’ fitness for surgery, post-operative outcomes, and successful weight loss. Our aim was to compare surgical outcome and weight loss in two groups of patients who were offered two different pre-operative kinds of diet: very low calorie diet (VLCD) and very low calorie ketogenic diet (VLCKD).


Patients candidate for bariatric surgery (laparoscopic sleeve gastrectomy) were registered and assessed according to pre- and post-diet BMI, operative time, hospital stay, drainage output, and hemoglobin (Hb) levels. Patients’ preference influenced the type of diet.


From January to December 2016, 178 patients (139 F and 39 M) were enrolled in this study. The mean age was 43 years. In total, 72 patients were on VLCKD while 106 patients on VLCD. Pre-diet mean BMI was 46.3 ± 6.3 kg/m2 for VLCKD group and 43.1 ± 6.9 kg/m2 for VLCD group, while immediately pre-op BMI were 43.9 ± 5.9 kg/m2 and 41.9 ± 6.8 kg/m2, respectively. Drainage output and hemoglobin levels after surgery resulted significantly correlated with diet induced BMI reduction (141.2 ± 75.8 vs. 190.7 ± 183.6 ml, p = 0.032; 13.1 ± 1.2 vs. 12.7 ± 1.5 g/l, p = 0.04). The percentage of patients requiring a hospital stay longer than anticipated (> 3 days) was 2.8% in the VLCKD group and 10.4% in the VLCD group (p = 0.048).


In our experience, VLCKD showed better results than VLCD on surgical outcome, influencing drainage output, post-operative hemoglobin levels, and hospital stay.

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Correspondence to Alice Albanese.

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Albanese, A., Prevedello, L., Markovich, M. et al. Pre-operative Very Low Calorie Ketogenic Diet (VLCKD) vs. Very Low Calorie Diet (VLCD): Surgical Impact. OBES SURG 29, 292–296 (2019).

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