With adequate exercise you won't lose muscle mass.
I work construction and went on a strict keto diet, I was losing ~1lb per weekday. I actually got stronger whilst on the diet, which I attribute to the increased testosterone that comes in after your body becomes adapted.
It's important to note that the Inuit used to live on an exclusive ketogenic diet, they also live in an environment that requires ~6,000 calories a day to simply maintain if living the traditional lifestyle.
What I found working outside whilst on keto and running into winter was that my body managed to maintain its heat extremely well and far better than previous years on a normal diet. I estimated my caloric use at between 4500-5000 a day by how much I ate and how much I lost.
As with any diet it's important to eat adequate protein and exercise. Protein is quite readily converted (very inefficiently) into sugar, and if you don't force it into ketosis you go into starvation and that's when you really risk muscle atrophy.
I work construction and went on a strict keto diet, I was losing ~1lb per weekday. I actually got stronger whilst on the diet, which I attribute to the increased testosterone that comes in after your body becomes adapted.
It's important to note that the Inuit used to live on an exclusive ketogenic diet, they also live in an environment that requires ~6,000 calories a day to simply maintain if living the traditional lifestyle.
What I found working outside whilst on keto and running into winter was that my body managed to maintain its heat extremely well and far better than previous years on a normal diet. I estimated my caloric use at between 4500-5000 a day by how much I ate and how much I lost.
As with any diet it's important to eat adequate protein and exercise. Protein is quite readily converted (very inefficiently) into sugar, and if you don't force it into ketosis you go into starvation and that's when you really risk muscle atrophy.