Pre-operative Very Low Calorie Ketogenic Diet (VLCKD) vs. Very Low
Calorie Diet (VLCD): Surgical Impact
Published online: 24 September 2018
#Springer Science+Business Media, LLC, part of Springer Nature 2018
Background Pre-operative diet may play an important role as far as patients’fitness for surgery, post-operative outcomes, and
successfulweight loss. Our aim was to compare surgical outcome and weight loss in two groups ofpatients who were offered two
different pre-operative kinds of diet: very low calorie diet (VLCD) and very low calorie ketogenic diet (VLCKD).
Methods 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 influ-
enced the type of diet.
Results 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/m
for VLCKD group
and 43.1 ± 6.9 kg/m
for VLCD group, while immediately pre-op BMI were 43.9± 5.9 kg/m
and 41.9 ± 6.8 kg/m
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).
Conclusions In our experience, VLCKD showed better results than VLCD on surgical outcome, influencing drainage output,
post-operative hemoglobin levels, and hospital stay.
Keywords Bariatric surgery .Pre-operative diet .Laparoscopic sleeve gastrectomy
Accurate pre-operative multidisciplinary assessment of bariat-
ric patients plays an important role in improving performance
status, surgical outcome, weight loss, and reducing the risk of
weight regain. Dietary assessment and pre-operative weight
loss has to be considered integrated in the surgical treatment.
Inadequate accessibility to the abdominal cavity due to
large fatty liver and visceral obesity is one of the major limit-
ing factors for surgery and has a negative impact on exposition
of the surgical field. Reducing hepatomegaly and visceral ad-
ipose tissue means having several technical advantages, re-
ducing potential injuries and complications during surgery,
and in the peri-operative period.
Very low calorie diet (VLCD) regimens and intragastric
balloon placement have already been investigated and have
an established role in the pre-operative weight loss [1,2]. The
role of very low calorie ketogenic diet (VLCKD ) is consoli-
dated and increasing in importance for obesity treatment and
type 2 diabetes mellitus (T2DM) [3,4], but their role before
bariatric surgery is still less considered. In addition, in the pre-
operative period, some issues have to be taken into consider-
ation as the influence of the catabolic state and the oxidative
stress induced by ketogenic diets.
Our purpose was to compare the effects on weight loss be-
tween a consolidated pre-operative diet (VLCD) and a new
dietetic approach in bariatric surgery (VLCKD). In particular,
we concentrated our analysis on the benefits provided by the
two regimens on surgical outcomes (mean operative time,
Bariatric Unit, Padua University Hospital, Padua, Italy
Obesity Surgery (2019) 29:292–296