Training on a keto diet is a hot topic and what people need to understand is that performance and fat loss are two sides of the same coin, BUT they are still different sides.
This means whilst whilst the goal you are focusing on is fat loss, any diet is generally going to cause some drop in performance. This should make complete sense as you don’t have as much energy coming in (calorie deficit) so you won’t have as much energy to put out
Along with this pretty much every diet limits carbs over the other macros and carbs are the best fuel for high intensity activities so when the diet gets really tight almost all diets become low carb to some extent.
So when you are starting a keto diet you have to expect some performance drops for two reasons.
Firstly most people start keto in a deficit and wonder why they feel crappy. Well this is pretty simple, you are trying to switch your bodies fuel source whilst also restricting it’s intake of overall fuel. If you are training hard there will be some time of adjustment which is why I always suggest people that are training start keto at least on maintenance calories.
The second reason is that carbs are an easy source of fuel and you’ve pretty much trained your body to rely on them. Keto used to be a natural state, during periods of cold where no plants were available or no food at all, ketosis kept us alive.
However now most people go their whole lives without even experiencing hunger let alone ketosis. So the transition is longer to become fat adapted. For example I will go a month to 6 weeks every year on a carb based diet around December. But as I’ve been doing this for over 10 years my body shifts back Into ketosis very quickly and I don’t notice a drop in performance.
But you have to train your body for this. You have to expect a period where things aren’t going to feel 100% and work through it and give your body the chance to “get used” to performing on keto.
Fat loss and performance are separate goals. Focus on one as your primary focus and try to optimise things for the other as best as possible. Just accept that there is NOT a fat burning diet that optimises performance and that you will not perform at you best in a deficit. Regardless of whether you’re eating carbs or not.