In recent years, the ketogenic diet- or keto for short- has become quite popular. This diet requires that you keep your carbohydrate consumption under 50 grams per day, which is about 5% of your energy intake. Protein consumption on the keto diet needs to be moderate to high, which is about 1.2...
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HOW DOES KETO AFFECT CORTISOL?
Since resting cortisol increases on short term but not long-term keto diets, it seems that it’s due to the role of glucocorticoids’ role in homeostasis of glucose. The following three factors increase on short-term keto, but not long-term keto diets:
- Cortisol
- Glucagon
- Gluconeogenesis
The initial increase in cortisol seems to be due to the temporary increase in gluconeogenesis due to glucocorticoids. Cortisol may also increase to keep glucose for brain functioning, as the brain can’t use fatty acids for fuel.
Research also shows that
cortisol levels increase more during workouts when on a low-carb diet than when on another type of diet. Therefore, it seems that the increase in cortisol during exercise is likely due to the lack of available carbs.
There are three possible explanations:
- On a low carb diet, glycogen stores are partially depleted, which means cortisol increases to facilitate gluconeogenesis while working out
- During workouts on a low-carb diet, fat oxidation is higher. Therefore, cortisol may increase to induce lipolysis in adipose tissue.
- Working out stimulates the uptake of glucose by skeletal muscles, which causes cortisol to increase, preserving glucose for brain function.
CONCLUSION
Most of the evidence indicates that cortisol increases on short term (less than three weeks) keto diets. Research also reveals that resting cortisol levels return to normal after approximately three weeks on a low-carb diet, but post-workout cortisol stays elevated.
That being said, since there are not many studies and there are discrepancies in the results of long-term low-carb diet studies, more research is needed to confirm the effects.
Finally, it also seems that low-carb, high-protein diets cause a significant decline in the levels of resting total testosterone, which indicates that those who are on this type of diet need to be careful about adverse effects on their endocrine system.