It's just another form of a calorie deficit. Replace the carbs with fats. The most important aspect in dieting (ie using nutrition to achieve one's goals) is calorie balance, calories you eat to what you burn each day. Most diets that work well will manipulate calories either directly or indirectly. Food composition, like eliminating something like carbs, has really only a superficial results, just like nutrient timing and the use of supplements and water. I fast during times I am leaning out, but really I am just finding a convenient way to achieve a calorie deficit. I honestly don't like eating or preparing breakfast early in the day. So when I am on a calorie deficit, I have found that fasting until around 11-noon helps on morning that I do not train. I still eat a meal on training mornings.
Try this, add back carbs and cut the fat and see what happens. Especially when you are training hard. Your workouts will get better for sure. But if you leaned out on Keto, and you are fit, as long as your calories are the same relatively, you'll stay just as lean most likely.