Cyclical ketogenic diet and carb refeeds

Potential conclusion (pending full texts): “if you’re gonna keto, no need to carb”

I think these three abstracts are all referring to the same studies.  I haven’t seen the full texts.  My takes are in italics, after each abstract.

Exhibit A. The Effects of an Eight Week Ketogenic Diet vs. a Cyclical Ketogenic Diet on Performance and Testosterone in a Resistance Training Program (Lane, Lowery, Volek, D’Agostino, Wilson, et al., 2015)

Introduction: Our lab recently examined the effects of the ketogenic diet (KD) compared to a western diet regarding strength related performance; additionally, free and total testosterone was evaluated. Individuals on the KD saw similar adaptations in strength and similar changes testosterone. Comparisons of the KD against a cyclic (CKD) in strength, endurance, and testosterone have not been previously demonstrated in literature.

Purpose: Therefore the purpose of this study was to investigate the effects of the KD versus a CKD on performance and testosterone in resistance-trained males.

Methods: Sixteen resistance trained males participated in the study (age: 23.5 ± 3.3; weight: 187.6 ± 32.6). Participants on the KD consumed 5% carbohydrate, 25% protein, and 70% fat for 8 weeks. The CKD group applied the same macronutrient ratio to their diet Monday through Friday, while altering the ratio on weekends (50% carbohydrate, 25% protein, 25% fat). A periodized resistance training program was strictly followed 3 days per week throughout the duration of the study with high intensity interval training implemented on intermittent days 2 times per week by all participants. Participants were placed on a 500 kcal deficit derived from basal metabolic rate determined by the Mifflin St. Jeor equation. One repetition maximum (1RM) strength was assessed on deadlift, bench press, and leg press at baseline with a repeat assessment performed Week 8. Strength endurance was assessed on the leg press at baseline and re-assessed at Week 8. Free and total testosterone was evaluated at baseline and at Week 8. An ANOVA with repeated-measures was used to scrutinize the effects of KD and CKD on dependent variables assuming group (KD and CKD) and time (pre and post) as fixed factors. The significance level was set at p ? 0.05.

Results: There were no differences between groups in the performance tests or testosterone levels detected at baseline (p > 0.05). A time effect was observed for bench press and deadlift 1RM (p < 0.01). There was a trend towards a group by time interaction (p = 0.07) which favored an increase in the leg press 1RM in the KD group. There were no significant differences for leg press strength endurance in both groups. For free testosterone, there were no group or group × time interactions (p > 0.05). For total testosterone, there was a group × time interaction following the diet treatment (p < 0.02). The pairwise comparisons revealed that only the cyclic group decreased in total testosterone (10.3%, p < 0.02).

Conclusions: In regards to performance, a strict KD seems to augment positive strength related adaptations when compared to a CKD. These responses may be explained by sustained total testosterone levels seen in the KD group compared to reductions in total testosterone as a result of the fluctuations in macronutrient intake.

Practical Applications: Individuals attempting to optimize adaptations in strength performance while maintaining testosterone levels should perform a KD compared to a CKD.

My take: no difference between KD & CKD, despite testosterone declining in CKD.  This isn’t surprising because small fluctuations within the physiological range are not expected to affect these outcomes.

When protein and calories are controlled, and the #context is a 500 kcal deficit, not really sure what they were expecting.  Because of the constant deficit, insulin will be low even on the carb-up days, and those carbs are more likely to be burned off than replenish glycogen.




Exhibit B. The 8 Week Effects of Low Carbohydrate Dieting vs. Very Low Carbohydrate Dieting With Refeed on Body Composition (Sharp, Lowery, Wilson, et al., 2015)

Introduction: Improvements in body composition are often deemed as by-products of dieting strategies. One common strategy is found within the manipulation of carbohydrate intake. Our laboratory recently investigated the effects of a very low carbohydrate diet (VLCD) vs. a traditional western diet combined with resistance training (RT) and found that a VLCD augmented adaptations in body composition. However, the comparison of a VLCD and a very low carbohydrate diet with a refeed (VLCRD) on body composition has not been observed.

Purpose: This study investigated the 8-week effects of 2 different very low carbohydrate dieting strategies on body composition in resistance-trained males.

Methods: Sixteen resistance trained college aged males were randomized into 2 groups: VLCD and VLCRD. Participants of the VLCD group consumed a diet consisting of 5% CHO, 25% PRO, and 70% FAT daily for duration of the study whereas the VLCRD consumed the same macronutrient profile for the first 5 days of each week with a refeed (50% CHO, 25% PRO, 25% FAT) on the final 2 days of each week. All participants engaged in a 5 days per week training protocol that consisted of 3 days per week periodized RT with 2 days per week of high intensity interval training. Each participant was individually consulted by a dietician to be placed on a 500 kcal deficit from basal intake calculated by the Mifflin St. Jeor equation. Body composition was determined by a 10 hours fasted DXA assessment at week 0 and week 8. Repeated measures ANOVA was used to evaluate group, time and group by time interactions. When significance was detected a Tukey’s Poc Hoc analysis was used to identify location of significance.

Results: A significant group × time interaction for body composition following the experimental period was detected (p < 0.002). Post-hoc comparisons indicated that only the VLCRD group significantly decreased LBM (p < 0.003, ?2.98%, [INCREMENT]: ?2.08 kg). There were no significant changes in LBM for the VLCD group. However, only the VLCD group significantly reduced FM (p < 0.001; ?19.6%; [INCREMENT]: ?2.70 kg). There were no significant changes in FM for the VLCRD group. In addition, an absolute delta change analysis showed differences between absolute changes for decrease LBM in VLCRD group and decreased FM for VLCD group.

Conclusions: Improvements in body composition appear to be enhanced in a strict VLCD when compared to a VLCRD when combined with resistance training after 8 weeks.

Practical Applications: Resistance trained individuals seeking improvements in body composition should consume a VLCD (5% CHO, 25% PRO, 70% FAT) in conjunction with periodized resistance training while avoiding a consecutive 2 day refeed (50% CHO, 25% PRO, 25% FAT) of carbohydrate.

My take: 1) NEED to see the dietary details & body comp numbers before coming to any conclusions.  This might be interesting. 



Bonus: The Effects of a Rapid Reintroduction of Carbohydrates Following a Ketogenic Diet (Partl, Lowery, Volek, D’Agostino, Wilson et al., 2015)

Introduction: Very low carbohydrate (70%) ketogenic diets (KD) diets have previously been shown to have favorable changes in body composition (increased lean mass and decreased fat mass) in resistance trained individuals [1]. Not surprisingly, KD’s are increasingly being used by bodybuilders and athletes to prepare for competitions. However, it is currently unknown how to properly reintroduce carbohydrates following a long period of keto adaptation.

Purpose: In order to simulate a final contest preparation week, the purpose of this study was to examine the short-term effects various rates of carbohydrate reintroduction had on body composition in resistance trained individuals transitioning off a KD.

Methods: Sixteen, college aged, resistance trained males participated in the study. Subjects were instructed to consume a ketogenic diet consisting of 5% carbohydrate, 25% protein, and 70% fat for 7 weeks. Additionally, subjects participated in a monitored, periodized resistance training program for the duration of the study. During week 8, subjects were divided into gradual (1 g·kg?1) or rapid (3 g·kg?1) carbohydrate reintroduction conditions. The other 8 subjects reintroduced carbohydrates to the diet at a rate of 3 g·kg?1. Body composition (Hologic Dual X-Ray Absorptiometry) was monitored every day until a “spillover” point was reached, defined as the point where there was no further changes in lean body mass in addition to increases in fat mass.

Results: Throughout days 1 and 2, no subject in either group demonstrated an increase in fat content. On day 3, only 1 participant (12.5%) in the low-carb group demonstrated an increase in fat content, whereas 4 participants (i.e., 50%) reported a fat content increase in the high-carb group. In addition, throughout days 4 and 5, 4 participants (50%) reported increases in fat content in the low-carb group. On the other hand, in the high-carb group, 8 participants (100%) reported increases in the fat content. Both groups increased LBM when compared to keto-adapted period (p < 0.0001) by days 1 and 2 with no differences between conditions. However, compared to day 1, only the 1 g·kg?1 significantly increased LBM at days 2 and 3 (p < 0.0001 and p < 0.001), respectively.

Conclusions: The primary finding of this study is that slow reintroduction of carbohydrate increases the ratio of DXA determined lean body mass to fat mass.

Practical Applications: Slow carb reintroduction likely peaks glycogen storage in 2–3 days. If using a faster rate of reintroduction, there is a greater chance of gaining fat mass. Thus, faster reintroductions should be kept to shorter periods.

My take: potential conclusion — carb bombs encourage fat storage more so than muscle growth..?  Short-term?  Need to see the actual study; the devil may just be in the details.

Potential conclusion (pending full texts): “if you’re gonna keto, no need to carb”



calories proper


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