Edit: scroll to bottom for TLDR version if you dont want to read the babbling 
First off, sorry for the long post. I have that sort of obsessive mind that won't stop until I have things just right. Ill try to include a lot of details that might be important so it might become lengthy.
BACKSTORY:
I'm 37 years old, 5'11". I've always been reasonably active and an on/off gym goer. In 2019 I prepped and did my first (and definitely last) bodybuilding show. I was at 173lbs, I dont remember body fat %. I wasn't as "cut" as I'd hoped, but definitely the best shape Ive ever been in. Long story short, the pendulum swung and I entered the world of "skinny fat." Made it up close to 210lbs.
Earlier this year I decided I was tired of being "skinny fat," eating donuts for breakfast, pizza for dinner, drinking a lot of alcohol. I didnt want to be the "fat dad." So I went back at it, stopped drinking, shifted my diet to a sort of modified carnivore/keto diet (meat, some vegetables, dairy, eggs). I went from 201lbs on January 6th to 175lbs on April 8th. I was getting pretty close to the physique I wanted. A lot of aches and pains gone, hiking and hunting would be easier.
In early June I went on a vacation and let loose, and had a hard time getting back into it when I came back. Fitness/diet was wishy washy and slowly weight came back. Again I found myself approaching "skinny fat," drinking a lot and just not being happy with myself. The pendulum swung again and on July 29th I decided to get back to it. I started at roughly 200lbs. As of today, 8/20 I'm down to 185lbs.
ROUTINE AND DIET:
I am not counting calories, or weighing food. Thats just not sustainable for me. I am keeping a rough count on protein in my head and make sure Im getting 0.75g-1g per lb of body weight. I have a fairly active job with a good amount of walking and some climbing, but once or twice a week it's mostly sitting. I go to the gym 3-4x/week (especially try to go on those "sitting days") and do resistance training and 10-15min LISS cardio (elliptical, inclined treadmill). Last detail, Ive been intermittent fasting. 16hr fast, 8hr eating window. Usually fast from 7pm-11am. All of these things are the exact same as earlier this when I went 201lb-175lbs in 3mo.
Now my question. This evening out of curiosity I checked the calories Ive eaten the last couple days. Both days are 1600 kcal - 1800 kcal. Im sure sometimes I eat a little more, but that's probably a safe average. My BMR is roughly 1800 kcal. If I burn somewhere around 1000kcal on a busy gym day, thats a 1000 kcal deficit. Isn't that... excessive? Crazy? When I run numbers on the weight loss in those time frames, it's a weight loss of about 0.28lbs/day and that translates to a 900-1000 kcal deficit. I have fine energy through the day. I dont feel super hungry (maybe a little towards the end of the fast), I sleep fine, my lifts are staying the same and sometimes going up. Part of me thinks, "why worry about it if I feel fine and I'm losing body fat?" But thats not what the goggles say...
MAJOR TL;DR:
I've seen that a significant calorie deficit can be detrimental. Should I worry about a 900 kcal deficit if weight loss is consistent, energy is fine, strength isn't being lost?
If you made it this far, thank you... sometimes it's cathartic to just type it out.
First off, sorry for the long post. I have that sort of obsessive mind that won't stop until I have things just right. Ill try to include a lot of details that might be important so it might become lengthy.
BACKSTORY:
I'm 37 years old, 5'11". I've always been reasonably active and an on/off gym goer. In 2019 I prepped and did my first (and definitely last) bodybuilding show. I was at 173lbs, I dont remember body fat %. I wasn't as "cut" as I'd hoped, but definitely the best shape Ive ever been in. Long story short, the pendulum swung and I entered the world of "skinny fat." Made it up close to 210lbs.
Earlier this year I decided I was tired of being "skinny fat," eating donuts for breakfast, pizza for dinner, drinking a lot of alcohol. I didnt want to be the "fat dad." So I went back at it, stopped drinking, shifted my diet to a sort of modified carnivore/keto diet (meat, some vegetables, dairy, eggs). I went from 201lbs on January 6th to 175lbs on April 8th. I was getting pretty close to the physique I wanted. A lot of aches and pains gone, hiking and hunting would be easier.
In early June I went on a vacation and let loose, and had a hard time getting back into it when I came back. Fitness/diet was wishy washy and slowly weight came back. Again I found myself approaching "skinny fat," drinking a lot and just not being happy with myself. The pendulum swung again and on July 29th I decided to get back to it. I started at roughly 200lbs. As of today, 8/20 I'm down to 185lbs.
ROUTINE AND DIET:
I am not counting calories, or weighing food. Thats just not sustainable for me. I am keeping a rough count on protein in my head and make sure Im getting 0.75g-1g per lb of body weight. I have a fairly active job with a good amount of walking and some climbing, but once or twice a week it's mostly sitting. I go to the gym 3-4x/week (especially try to go on those "sitting days") and do resistance training and 10-15min LISS cardio (elliptical, inclined treadmill). Last detail, Ive been intermittent fasting. 16hr fast, 8hr eating window. Usually fast from 7pm-11am. All of these things are the exact same as earlier this when I went 201lb-175lbs in 3mo.
Now my question. This evening out of curiosity I checked the calories Ive eaten the last couple days. Both days are 1600 kcal - 1800 kcal. Im sure sometimes I eat a little more, but that's probably a safe average. My BMR is roughly 1800 kcal. If I burn somewhere around 1000kcal on a busy gym day, thats a 1000 kcal deficit. Isn't that... excessive? Crazy? When I run numbers on the weight loss in those time frames, it's a weight loss of about 0.28lbs/day and that translates to a 900-1000 kcal deficit. I have fine energy through the day. I dont feel super hungry (maybe a little towards the end of the fast), I sleep fine, my lifts are staying the same and sometimes going up. Part of me thinks, "why worry about it if I feel fine and I'm losing body fat?" But thats not what the goggles say...
MAJOR TL;DR:
I've seen that a significant calorie deficit can be detrimental. Should I worry about a 900 kcal deficit if weight loss is consistent, energy is fine, strength isn't being lost?
If you made it this far, thank you... sometimes it's cathartic to just type it out.
