It seems like 2017 is the year of the ketogenic diet. A new study examined the impacts of a 6-week ketogenic diet on body composition, health and fitness markers in healthy middle-aged men. So, if you’re active and want to take a glimpse into the effects of adopting a keto diet may have on your health and performance, here is your chance to take a sneak peek. Let’s review
Forty-two men in their late 30s were recruited for this 6-week study. They were fed a non-calorically restricted ketogenic diet – comprised of 70% fat, 20% protein and 10% carbs - and assessed for ketosis using urinary testing.(1)
1) Weight loss
Ketogenic diets are a very effective tool for weight loss. Interestingly, even in this calorically controlled study, the men lost an average of five pounds, half of which was lean muscle and half body-fat.
Hand-grip strength was tested over the 6-weeks and it rose marginally by 2.5% during the month and half, although the results are not statistically significant.
3) Endurance Capacity
Cycle endurance exercise capacity was compromised in the men, falling by 2.4% over the course of the study. While this effect is minimal in a recreational exerciser, it can be a game-changer for professional or elite athletes. It can take up to six months (sometimes even a year) to fully regain your performance after adopting a keto diet.
4) Peak Power
Like endurance capacity, peak power cycling also declined in the subjects by an average of 4.1%. This is a common finding in new “keto athletes”, you lose some horse power in your top gear.
5) Blood Lipid Changes
Total and LDL cholesterol levels increased by 4.7 and 10.7%, respectively in the men, whereas there were no changes in triglycerides or HDL cholesterol.
6) Glucose & Insulin
Not surprisingly, blood sugar levels dropped by 3.0% in men and fasting insulin levels by 22.2%. The insulin reduction is quite impressive, considering these were healthy men, and reinforces the evidence that supports the ketogenic diet being the biggest “metabolic hammer” to lower insulin levels.
Insulin like growth factor (IGF-1) is a powerful anabolic hormone and is commonly dramatically elevated in overweight, obese and diabetic subjects, contributing strongly to the disease progression. The keto diet could drop IGF-1 levels by 20.2 % in these healthy middle-aged men.
A ketogenic diet can be a powerful tool for many goals. In the general population, it’s great for weight loss and improving blood sugar and insulin levels - key underlying factors to most all chronic diseases – and results in only mildly detrimental impacts on exercise performance. This can often be off-set by simply adhering to a keto diet for a longer period of time. However, in elite or professional athletes engaging in heavily glycolytic sports, the cost of reduction in power and reduced endurance capacity may be too high a price to offset the benefits of a keto approach. Have clarity in your goals and pick the right nutrition “tool” to achieve it!
Dr. Marc Bubbs ND, CISSN, CSCS
Want to learn more? Listen to expert Ryan Lowery PhD(c) talk keto diets and performance on Episode #33 of the Dr. Bubbs Performance Podcast...
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