The Influence of Cyclical Ketogenic Reduction Diet vs. Nutritionally Balanced Reduction Diet on Body Composition, Strength, and Endurance Performance in Healthy Young Males: A Randomized Controlled Trial

Abstract

(1) Background: The influence of ketogenic diet on physical fitness remains controversial. We performed a randomized controlled trial to compare the effect of cyclical ketogenic reduction diet (CKD) vs. nutritionally balanced reduction diet (RD) on body composition, muscle strength, and endurance performance. (2) Methods: 25 healthy young males undergoing regular resistance training combined with aerobic training were randomized to CKD (n = 13) or RD (n = 12). Body composition, muscle strength and spiroergometric parameters were measured at baseline and after eight weeks of intervention. (3) Results: Both CKD and RD decreased body weight, body fat, and BMI. Lean body mass and body water decreased in CKD and did not significantly change in RD group. Muscle strength parameters were not affected in CKD while in RD group lat pull-down and leg press values increased. Similarly, endurance performance was not changed in CKD group while in RD group peak workload and peak oxygen uptake increased. (4) Conclusions: Our data show that in healthy young males undergoing resistance and aerobic training comparable weight reduction were achieved by CKD and RD. In RD group; improved muscle strength and endurance performance was noted relative to neutral effect of CKD that also slightly reduced lean body mass.

Efficacy of Popular Diets Applied by Endurance Athletes on Sports Performance: Beneficial or Detrimental? A Narrative Review

“…These findings raised doubts about the use of KD for weight loss in endurance athletes. In addition to that, a recent study compared the efficiency of two energy-reduced (−500 kcal·day −1 ) diets, including a cyclical ketogenic reduction diet (CKD), defined as a high-fat low-CHO (>30 g·day −1 ) diet for five days, followed by a high carb diet (8–10 g/body FFM) for two days, and a nutritionally balanced reduction diet (RD), a typical diet containing 55% CHO, 15% protein, and 30% fat, on body composition and endurance performance in healthy young males [ 135 ]. Results revealed that both diets reduced body weight and body fat mass.…”

“…Results revealed that both diets reduced body weight and body fat mass. However, while CKD-related weight loss is due to decreased body fat, body water, and lean body mass, RD leads to a reduction in body weight mainly by reducing body fat mass [ 135 ]. Among all of these findings, one should note that adherence to a weight loss diet is major factor in achieving a target that does not significantly require KD consumption.…”

Effects of Combining a Ketogenic Diet with Resistance Training on Body Composition, Strength, and Mechanical Power in Trained Individuals: A Narrative Review

“…Different studies support the effect of KDs vs. non-KDs in the reduction of both total body and fat mass [ 25 , 26 , 27 , 28 , 29 , 30 ]. However, some detrimental effects have been reported on muscle mass when KDs are combined with resistance exercise interventions [ 25 , 26 , 27 , 28 , 31 ]. A randomized controlled trial conducted with Olympic-class weightlifters reported that a 3-month ad libitum KD resulted in a total loss of body mass above 3 kg compared with a group maintaining their usual diet (~45% carbohydrate) [ 26 ].…”

“…However, whereas the control groups showed a trend to increase fat-free mass (~by 1.3 and 0.7 kg for men and women, respectively), participants on the KD showed no changes [ 27 , 28 ]. Recently, Kysel et al [ 31 ] found a comparable reduction in body mass in healthy young resistance-trained men who combined resistance and aerobic training with (i) a hypocaloric cyclical KD (i.e., 500-kcal energy deficit alternating a phase of KD for 5 days followed by 2 days of carbohydrate reintroduction) or (ii) a hypocaloric non-KD diet, for 8 weeks. Although no significant between-group differences were found at post-intervention (KD −4.6 kg vs. non-KD, 4.5 kg), only participants assigned to the KD treatment showed a significant reduction in muscle mass (KD −1.8 kg vs. non-KD −0.4 kg).…”

“…In the study by Wilson et al, those participants who followed a non-KD over 10 weeks increased their peak power output on a Wingate test, whereas those who followed a KD did not, albeit with no significant differences in the pre-post change between conditions [ 29 ]. Kysel et al reported larger benefits on maximal strength (1RM on the bench press and lateral pull-down exercises) and on some markers of cardiorespiratory fitness (peak oxygen uptake and peak workload during an incremental test) in individuals who followed a hypocaloric non-KD compared with those who followed a hypocaloric cyclical KD [ 31 ]. In a non-controlled study by Urbain et al, participants who followed a KD for 6 weeks showed an impairment of peak power during an incremental cycling test (−4.1%), although handgrip strength increased slightly (+2.5%) [ 67 ].…”