From her book, "The Wahls Protocol" it is an extension of the popular Paleo diet. The "level 1" diet is simply:
9 cups of fruits & vegetables per day + 4-6 ounces of organ meats. Technically all meat is organ meat, but she's specifically referring to liver, kidneys, etc) 3 cups of greens, 3 cups of color, 3 cups of sulfur. Greens are things like spinach, kale, lettuce, etc. Color are fully deep color items like tomatoes, blackberries, rasberries. Apples & Banans don't count. Sulfure are items like broccoli, cauliflower, onions, radishes.
In her 3rd level she adopts a partially ketogenic (high fat) strategy and drops down the veggies & fruits to 6 cups with a 2/2/2 distribution. The different levels eliminate certain classes of foods. Level 1 removes gluten & dairy as they tend to be items that affect a large enough percentage of the population. Level 2 removes grains & legumes, Level 3 adds higher fat. There is also the advice to remove processed foods and oxidized fats, etc.
Magnesium(Mg) is responsible for 300+ chemical reactions in the body and is store intracellularly, thus only a limited amount is available. Too much Mg all at once causes bowel distress. The way to store large amounts of Mg is to get it from greens in as fibrous of a form as possible. Chlorophyl molecues contain a Mg ion, thus eating greens allows the Mg + other vitamins and minerals to stay in the large intestine for an extended amount of time and be made available for whichever processes are needed.
For optimizing lipid metabolism, the supplementing l-carnitine assists with that process.
For optimizing general neural stamina, the amino acids (and semi amino-acids) acetyl-l-carnitine, acetyl-l-tyrosine, taurine, l-theanine also have a positive effect on stamina alongside plenty of research on pubmed to corroborate said effects.
The neurotransmitters orexin-a (aka hypocretin-a) & histamine are responsible for regulating wakefulness. orexin receptors are in people's eyes. It's the reason people wake up when light comes in. The light stimulates orexin release into the brain and the brain wakes up.
When needing lots of mental energy & stamina, there is already plenty of caloric energy available as lipids in the body. What is really needed is the assistance of lipid breakdown into Acetyl-COA so that it can become ATP. Also plenty of potassium, Mg, other vitamins assist in this process.
Since insulin & orexin seem to be antagonistic (not sure of the right word) neurotransmitters, glucose intake tends to release insulin, which then "shuts down" the orexin receptors which regulate wakefulness. Insulin is released based on blood plasma levels of glucose. Sugar in a high glycemic form as sugar, tends to spike insulin. If order to optimize for wakefulness, we tends to want to keep insulin levels as low as possible. Insulin's main uses are to signal to the muscles to store up glucose, store away lipids for future energy. In order to store away muslce glycogen, muscles use up water for storing away glycogen. Being insulin-resistant (aka pre-diabetes) probably stems from all the glycogen already being stored away and not having any place to store said glycogen, thus blood plasma levels of sugar remain high for extended periods of time. It makes sense why general exercise (glycogen depletion/use) helps pre-diabetics to go into recovery/remission as glucose can be readily stored away. This explains a large part of why fasting help with wakefulnes and mental clarity. Those who have taken provigil understand the feeling of having lots of orexin available in the brain. It increases mental performance and keep someone awake. Provigil affects orexin reuptake thus makes that particular neurotransmitter available. From my experience, Provigil tolerances tend to stem from other nutritional deficiencies and adding the other chemistry helps tremendously.
Now as far as resetting the circadian clock. Orexin being the wakefulness neurotransmitter to hack is what allows one to stay away for extended periods of time. Having enough orexin to allow someone to power through to a new timezone's evening, finally allows the body to reach fatigue at the appropriate evening hour, resets the circadian clock and allows for the adjustment to happen relatively quickly. I've found that going west is easy. You stay up longer and wake up later. The challenge of moving east is difficult as one has to sleep earlier and wake up earlier. The problem with going east is that it's hard to fall asleep early, then staying up allow night means waking up very late and combating the same problem. One way to go east is to either pull the equivalent of 1-2 all nighters a la orexin hacks (reduce sleepiness via reducing glucose intake). For those that are awake due to being caffeinated, L-Theanine is the counter to caffeine allowing for more restful sleep despite caffeine intake. Naturally, Caffiene & L-Theanine exist together in green tea leaves and allows for a calming, less jittery effect when consumed together. L-Theanine also tends to work for helping sleep quality. The other item to help with sleep is Taurine as it allows for deeper, more restful sleep. Adding in the chemical components that help sleep and help wakefulness let us hack around how much the body can handle even at older ages.