The low-carb & high-fat diet (includes keto-diet) are not good for you because the brain needs glucose for fuel. It can burn fat. But, the brain’s preferred energy source is glucose. The key is to provide the brain with glucose without raising glucose/serum blood level. You do that by avoiding sugar and eating complex carbohydrates (fresh produce) that convert into glucose.
More than once I have seen results indicating that high-IQ types benefit the least from random nootropics; nutritional deficits are the premier example, because high-IQ types almost by definition suffer from no major deficiencies like iodine. But a stimulant modafinil may be another such nootropic (see Cognitive effects of modafinil in student volunteers may depend on IQ, Randall et al 2005), which mentions:

NeuroFuse was almost there with a top quality product but we felt that there were several key elements missing. It does contain a lot of the top natural ingredients for cognitive energy enhancement. However, the fact that their money-back guarantee is not apparent and that they are baiting customers in using a 14-day free trial offer, made us slightly wary. If they addressed these issues, we felt that this could have been a winner!
Eugeroics (armodafinil and modafinil) – are classified as "wakefulness promoting" agents; modafinil increased alertness, particularly in sleep deprived individuals, and was noted to facilitate reasoning and problem solving in non-ADHD youth.[23] In a systematic review of small, preliminary studies where the effects of modafinil were examined, when simple psychometric assessments were considered, modafinil intake appeared to enhance executive function.[27] Modafinil does not produce improvements in mood or motivation in sleep deprived or non-sleep deprived individuals.[28]
My worry about the MP variable is that, plausible or not, it does seem relatively weak against manipulation; other variables I could look at, like arbtt window-tracking of how I spend my computer time, # or size of edits to my files, or spaced repetition performance, would be harder to manipulate. If it’s all due to MP, then if I remove the MP and LLLT variables, and summarize all the other variables with factor analysis into 2 or 3 variables, then I should see no increases in them when I put LLLT back in and look for a correlation between the factors & LLLT with a multivariate regression.

There are a ton of great rosemary snack options. Personally, I always keep some flavored natural sea salts in my desk to spice up my snacks and meals at the office. Here’s a great option for rosemary flavored sea salt. Another great choice is the Parmesan Rosemary Popcorn from Quinn’s Popcorn. They never use GMO corn, coatings or chemicals on the bag, or any other scary stuff found in traditional microwave popcorn. This is truly microwave popcorn reinvented.
Be patient.  Even though you may notice some improvements right away (sometimes within the first day), you should give your brain supplement at least several months to work.  The positive effects are cumulative, and most people do not max out their brain potential on a supplement until they have used it for at least 90 days.  That is when the really dramatic effects start kicking in!
She repeats the oft-refuted advice to drink at least 8 glasses of water a day. She claims that drinking water improves cognitive performance. Her citation for that claim is a small study in which participants were instructed to fast overnight and not eat or drink anything after 9 pm, so they were presumably somewhat dehydrated. There is no evidence that people who are not dehydrated benefit from increasing water intake.

Methylphenidate – a benzylpiperidine that had cognitive effects (e.g., working memory, episodic memory, and inhibitory control, aspects of attention, and planning latency) in healthy people.[21][22][23] It also may improve task saliency and performance on tedious tasks.[25] At above optimal doses, methylphenidate had off–target effects that decreased learning.[26]