THE EFFECTS OF VARIOUS PROTEIN TYPES ON INDICATORS OF KETOSIS
C. IRVIN Journal of Strength & Conditioning Research VOLUME 30 | SUPPLEMENT 1 | DECEMBER 2016 | S107
A ketogenic diet is a high fat, very low carbohydrate diet that
seems to have many therapeutic and performance benefits. It is
often recommended for protein to make up 20–25% of total
caloric intake when consuming a ketogenic diet. Consuming
a large bolus of protein can cause an influx in circulating amino
acids leading to a rise in blood glucose through gluconeogenesis
and drop in blood ketones which could be harmful for
a ketogenic athlete.
Purpose: Considering that supplemental
proteins contain varying digestion rates, the purpose of this
study was to test effects of 3 different types of protein (Whey,
Casein, and Egg) on blood markers of ketosis. Methods:
Twenty-two resistance trained men and women 18–30 years
old (mean 6 SD, Age: 22 6 3, Weight: 78.25 6 11.95 kg,
Height: 175.78 6 10.40 cm) were placed on a calorie controlled
ketogenic diet for 2 weeks to allow for adaptation to
occur. In a randomized, crossover design, subjects were given
25 g of supplemental protein in the form of either whey, casein,
or egg protein. Subjects arrived to the laboratory following
a 10-hour water only fast, consumed supplemental protein,
and were instructed to remain seated to prevent activity
induced changes in blood glucose. Blood glucose and ketone
levels were monitored via Precision Xtra Monitoring Device at
baseline, 30, 60, 90, 120, and 180 minutes. Subjects completed
a 48-hour washout period between conditions. Two-way
ANOVA for repeated measures assessed plasma glucose and
ketone concentrations assuming condition (Whey, Casein and
Egg) and time as fixed factors. Area under the curve (AUC),
Cmax, and Tmax were analyzed by one-way ANOVA for
repeated measures. Whenever a significant F-value was obtained,
a Tukey post-hoc test was performed. Significance level
was set at p # 0.05.
Results: At baseline there were no
between-condition differences or differences for total AUC
for blood glucose or blood ketones, Cmax, or Tmax. Within condition
comparisons for blood ketone levels indicated no
changes occurred relative to baseline in any condition.
The Whey condition demonstrated within-condition differences for
blood glucose wherein the mean value at 30 minutes was
significantly higher than baseline (p # 0.05), 120 (p # 0.05)
and 180 minutes (p , 0.0001). Additionally, the Casein
condition was significantly higher at 30 minutes than 60
(p , 0.01), 120 (p , 0.01) and 180 minutes (p , 0.0001)
with a strong trend compared to baseline (p = 0.052).
Conclusions: Our data suggests that protein source does
not impact blood ketone levels relative to baseline. However,
dairy proteins do elevate blood glucose.
Practical Applications:
Athletes attempting to maintain ketosis can use a variety
of dairy and egg protein sources. However, if attempting to
keep blood glucose from rising egg based sources may be
a better selection.
