I've been pretty much keto for the past 7 years.  Varying from strict to dirty to during the week with cheat weekends.  Since January, my weight has been stable (within 5 pounds).  

For the past month, I decided to do one meal a day.  Dinner, usually around 7:30 PM.  I still cheat a little on the weekends in terms of type of food, but still keep it to one meal.  I'm feeling that I'm not getting enough calories, but the weight stability is telling me I am.  My issue is that I have no energy and feel "not right," in an unexplainable way.  An example dinner would be 4 egg cheese omelette.

My stats are 50 yo male, 5'7" 146 pounds.  Lightly active.

Any thoughts would be appreciated.

Add Bacon!!!

Make it a 'window period' rather than a meal.  For you, perhaps eating only within a three hour span.  You have your usual meal then can eat again a bit later.

It takes getting used to. I've been doing it (with Keto) since about christmas. I get a little light in the brain around 3pm, but my window is 4-8 or so. I do lunch on the weekends and really the only tough day is Monday.
lots and lots of water, and an after-dinner snack (before 8) helps, I actually am losing more weight than just the one meal. I bought a whipped cream maker and do heavy cream with some sweetener. Just enough of a snack it feels like dessert and I think it's helped me hit fat macros.

Been doing this for 25 years. Not keto anymore. The first several years it was pretty bad because I was inconsistent and would frequently eat several hours before going to bed. Now I eat within an hour of going to bed and that helps a lot. There's still nutrient uptake going on when I wake up so I'm not hitting low blood sugar and getting hunger headaches in the middle of the day. I found that full keto really didn't mix well with the system and timing. I need a small helping of carbs to carry my blood sugar through the night and if I burn a lot of calories during the day then I need to do a feed bump of meat and fat to get right. It takes a while to train your body to only ask for food when it needs it and then when it asks you really need to pay attention but keep the out of schedule intake to a minimum or it'll blow your appetite for your evening meal and it can take days to get back on track.

My meal sizes are tiny on days where I just ride the desk but when I start lifting servers into racks and running around all day I will often need to crunch down a handful of cashews and some meat or boiled egg(s).

For your example meal at least, unless you literally have a full pound of cheese with you eggs, you're at a calorie deficit.

Just thinking about that makes my asshole hurt.

This is what I don't understand.  Most days my calorie intake is well under 1000.

However, tonight I had beef with mushrooms (and the rice) from the Chinese place.  It filled me up but not stuffed.

Are you familiar with bioavailability? Meats are much more bioavailable than plants. When you eat just plants you shit out a lot of it so you don't get the full caloric value. Not so much with meat.

LOL yeah.  When I was full keto I only went once a week

Have you tried adjusting the time of day such as omad at lunch? I read the post earlier that said just before bed helps, but it was terrible for me
Made it harder to sleep and im not sure if it was just the change or having time to dogest before going to bed that helped me get over a slump. I think just changing things up sometimes can have a big impact. The first few days will suck. Best of luck.