I basically switched to essentially the vertical diet about 8 years ago after reading a book called “The Perfect Health Diet”. Why it worked IMO. 1) It controlled carbs but kept them high enough to keep me feeling like I was eating normally, 2) I eliminated high linoleic oils, 3) I kept fructose at an optimal level, usually less than 25 grams per day, 4) I eliminated wheat, oats, most corn and beans, and later on, other foods that were irritating. For me, the same foods that are irritants are trigger foods for throwing me off of eating right. When you avoid those trigger foods, you start to crave things that your body really needs rather than those inflammatory trigger foods. The thing is that cortisol has some addictive properties, so cortisol raising foods can make you eat for the chemical response rather than the nutritional need.
In my case, I did this step-wise, and when I cut grains (except white rice) and beans, I started sleeping much better because I had sinus inflammation most nights, and removing grains and beans shut off my sinus inflammation immediately. I’ve tried to add them back and the night time sinusitis came back right away.
To this day, if I add back sugar (aside from about as much fruit as I want), or linoleic oils, or canola or wheat, or beans, I get foggy headed, and my sleep quality falls off dramatically. I’ve also come to cut milk most of the time as well. I don’t have noticeable gut issues from any of those foods, but I absolutely get sinus inflammation and general inflammation from them, and they tend to show up most at night. There is no doubt that I was wheat sensitive. As for the high linoleic oils, they are highly systematically inflammatory. Cutting linoleic acid intake can make people feel a lot better right away by reducing inflammation. This also leads to improved insulin sensitivity. Wheat can take 50% more insulin to manage than other carbs because it triggers cortisol release from gut irritation. The reason that high gluten wheat has a low GI is because it contains gut irritants that distress the intestinal lining and make it slower to absorb, but also require more insulin in the long run due to spiking cortisol level as a response to the inflammation.
Obviously, the diet also keeps blood sugar levels very stable because of the balanced macros.
Other things may be the higher cholesterol intake which keeps hormones optimized, and also the sodium. I tended to get really low sodium when I ate right, and adding more sodium improved my workouts. I CAN train in the morning on limited carbs but I need sodium. I have come to think that a main benefit of Plasma or Mag-10 is the sodium content.