This is actually one of the many variations of the Adkins diet, possibly one of the most restrictive of all low carbohydrate diets, but they work on the same basic principle. -- once the body is starved of carbohydrates, rather than manufacturing glucose for energy, the body converts fat to fatty acids and ketones instead, entering into a state called "ketosis." You can buy paper strips at drug stores to test your urine for ketones to ensure your body has entered and is maintaining this state.
In a ketogenic diet for epilepsy, the goal is to achieve a fat to protein ratio of 4:1, meaning that for every of 1 ounce of protein, you consume 4 ounces of fat. Carbohydrates are either eliminated completely or minimal, as part of the protein ratio. To acheive this ratio, children with epilepsy on this diet will drink oil, mixed with small quantities of milk.
No veggies, no fruits, no grains (breads) no starches (pastas, potatoes, rice, etc) and instead, you consume as much meat and fat as you want. You can eat a dozen eggs fried in a pound of butter, along with a pound of bacon for breakfast, and still lose weight! Without carbs., your body will only digest and absorb just so many calories from fats and proteins per day. That's not entirely true, but to a certain extent, it is. I have gone on several variations of this diet. And no matter how many calories I consume, the pounds just roll off.
It's been proven effective for epilepsy, especially for children suffering certain types, and is also being used to treat a number of other conditions, including diabetes and cancer, but lets not go there.
I could see how this might be beneficial, particularly to those whose systems can not tolerate fiber, and who may be overweight, particularly from long term use of steroids. Not much fiber on this diet, but many with Crohns and other related disorders can't tolerate much fiber.
It also tends to cause constipation, so may be helpful for diarrhea.
But for those who are underweight already, I don't know if this would be a good diet, not without adding sufficient carbs to assisting digesting and absorbing nutrients and calories from food--in which case, I would think the SCD would make more sense.
Added:
If you do go on this diet, it would be great if you would post your journey in the supplement section so we can follow your experience. I personally have been exploring and experimenting with the effect of dietary changes, so I would be interested in following yours.
I wish you the best!