Metabolic flexibility is the bodies ability to burn the fuel that is available easily. This includes stored glycogen i.e blood-liver sugar or fat from circulation and adipose-Fat tissue. Flexability means when required or for intense effort glucose is available, you burn that, but when it’s not fat buring easily happens. This makes you a more metabolically flexible person which can use fatty acids and ketones for fuel. This allows you to be self sufficient and not dependent on one single fuel source such as glycogen -blood sugar which is limited in comparison to free Fatty acids and adipose tissue supplies.

Gaining metabolically flexible may require some metabolic training, and you might have to put in some work to teach your body how to switch from glucose to alternative fuel sources. It can be a bit of a process, but a worthy one! This involves an adaptation period where insulin is suppressed to the point that we can start breaking down our own fat for fuel, and if sustained long enough, enter ketosis! It’s almost like training ourselves to be hybrid cars. Metabolic flexibility has the potential to have a powerful impact on overall health, and it’s a topic we’ll be diving into again 

Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes

Highlights

• Nutritional ketone bodies like GoKeto can promote the advantageous aspects to ketosis & timing of macro nutrient intake.

• Nutritional ketosis alters the hierarchy of substrate competition for respiration in exercise.

• Ketosis increases metabolic flexibility during exercise, reducing glycolysis and increasing muscle fat oxidation.

• Improved performance during training/recovery suggests ketosis during exercise training may be very beneficial.

• Enhanced metabolic efficiency- so gain greater adaptation responces and over condition.

Can keto actually work for hard training endurance or powerstrength athletes? well yes. 

Summary

Ketosis, the metabolic response to energy crisis, is a mechanism to sustain life by altering oxidative fuel selection. Often overlooked for its metabolic potential, ketosis is poorly understood outside of starvation or diabetic crisis. Thus, we studied the biochemical advantages of ketosis in humans using a ketone ester-based form of nutrition without the unwanted milieu of endogenous ketone body production by caloric or carbohydrate restriction. In five separate studies of 39 high-performance athletes, we show how this unique metabolic state improves physical endurance by altering fuel competition for oxidative respiration. Ketosis decreased muscle glycolysis and plasma lactate concentrations, while providing an alternative substrate for oxidative phosphorylation. Ketosis increased intramuscular triacylglycerol oxidation during exercise, even in the presence of normal muscle glycogen, co-ingested carbohydrate and elevated insulin. These findings may hold clues to greater human potential and a better understanding of fuel metabolism in health and disease.

http://www.cell.com/cell-metabolism/fulltext/S1550-4131(16)30355-2