I think you may be experiencing what I did on an ultra low carb diet. I did try to follow the "20 grams of carbs" approach but it didn't work for me. I felt sluggish, I was tired, and anxious (especially that anxiety!). Having said that, I have Hashimoto's (autoimmune hypothyroid condition) and I can't do very low-carb for that very reason. These days I eat 20-30 grams of net carbs, sometimes up to 50, especially after a workout when my body naturally craves carbs. Keep in mind that some people tend to overemphasise the importance of high ketones while it's not as simple and most people don't even need high ketones: The Ketone Craze - Who Really Benefits From High Ketone Levels? I hope this helps!

For obesity-reduction experts, it is well known that the main obstacle to follow a hypocaloric diet is hunger. In fact, within a few days after undertaking such a calorie-lowered diet, patients suffered a battery of negative effects, such as hunger, sadness, bad humor, and, in some cases, mild depression. All these side effects were absent in the patients following a VLCK diet, thus contributing to the success of these types of treatments. The mechanism that erases hunger and sadness in obese subjects following a VLCK diet are not known, and several authors strongly believe that it is due to the anorexigenic effect of ketosis [42]. As a result, of that rationale, the target of this work was to study the neurocognitive effects of ketosis, using a battery of neurocognitive and QoL tests in the same individuals at three different stages; (a) nonketosis-nonweight reduction (basal), (b) highly ketosis-mild weight reduction (visit 2), and (c) nonketosis-strong (mean 20 kg) weight reduction.
Although the exact role of the keto diet in mental and brain disorders is unclear, there has been proof of its efficacy in patients with schizophrenia. And, to boot, it works to reverse many conditions that develop as a side effect of conventional medications for brain disorders, like weight gain, type 2 diabetes and cardiovascular risks. More research is needed to understand the role of the ketogenic diet in treating or improving schizophrenia, as the current available studies are either animal studies or case studies, but the benefits of a low carbohydrate, high-fat diet in neurology is promising.
Getting into ketosis is a critical component of the ketogenic diet. You can achieve ketosis by fasting, cutting carbs drastically (typically under 50 grams a day), and/or taking keto supplements, such as BHB (exogenous ketones) and MCT-based meal replacement shakes. After becoming fat-adapted, incorporating intermittent fasting (IF) can help boost weight loss or break weight loss plateaus. The most common method is 16:8 where you go 16 hours without eating, and consume all of your calories during an 8-hour eating window.
Aude, Y., A. S, Agatston, F. Lopez-Jimenez, et al. “The National Cholesterol Education Program Diet vs a Diet Lower in Carbohydrates and Higher in Protein and Monounsaturated Fat: A Randomized Trial.” JAMA Internal Medicine 164, no. 19 (2004): 2141–46. doi: 10.1001/archinte.164.19.2141. jamanetwork.com/journals/jamainternalmedicine/article-abstract/217514.

In the first week, many people report headaches, mental fogginess, dizziness, and aggravation. Most of the time, this is the result of your electrolytes being flushed out, as ketosis has a diuretic effect. Make sure you drink plenty of water and keep your sodium intake up.6One of the fathers of keto, Dr. Phinney, shows that electrolyte levels (especially sodium) can become unbalanced with low carb intake.
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