After many years of OMAD (one meal a day), I have found that I am most sluggish in the day, right after eating. I am more mentally alert and physically strong in the mornings, after fasting for more than 20hrs of fasting. Why is this? It is becoming clear that glucose is not the best way to feed our brains, ketones are. However, unless you ate a carbohydrate-free diet, you are going to spike Insulin after a meal. Insulin suppresses other hormones, including Glucagon, HGH, and Testosterone. Glucagon promotes ketogenesis and HGH promotes muscle growth and cellular regeneration. Meanwhile, Sugar, being addictive, give us a feeling of joy, but only for a short period of time. We then go from depression to euphoria in a never-ending cycle. 

Intermittent Fasting (IF) and specially OMAD people report increased cognitive abilities. During my previous OMAD regimen (from 2009 to 2014), I learned 3 languages, build 2 websites, and ran 2 businesses. I even wrote some music, something I had never done in my life. Although I did not know it then, I have to believe that I was in a sustained state of ketosis. Ketone bodies provide a more efficient source of energy for the entire body, and brain as part of it. Therefore, it follows that IF is an excellent way to enter ketosis and improve cognitive functions.