No. No. This is also inaccurate. Everybody has a different metabolism, thus having different rates of burning food. Example - I am a "Hardgainer"; It is tough for me to put on and maintain weight. My maintenance is 2500 clalories a day jus to maintain!

.  I will post something later that will allow everybody to find their maintenance.

It's usually about the balance of nutrients. While proteins are the building blocks for the expansion of muscle cells, carbs are the fuel (glucose). If your blood glucose levels are too low on average, and especially during or around workouts, you will not only see subpar performance but also a smaller degree of hypertrophy since low blood glucose typically means inhibited protein synthesis and thus less actual use of said building blocks. One of the most common dietary mistakes is not filling up the blood glucose levels after a workout, limiting the body's ability to and interest in building muscle. Strength gain is somewhat easier since it's more about neural adaptation than the actual size of the muscle itself (in other words; two muscles of roughly equal size can be neurally adapted to performing at completely different levels), but there is, of course, a connection between the size and strength of a muscle as well.

Proponents of keto diets will argue that one doesn't need carbs at all, or very little of it. The problem with that is that the majority of people who attempt to go into ketosis don't actually succeed in doing so, or they do at an intermittent rate. Either way, they're unlikely to become free of glucose dependency in their training (keto diets are really hard for most people).

TLDR: Calories are only a piece of the puzzle, nutrients are more important, specifically the balance between them and to a lesser extent the timing of their intake.

PS: For simultaneous weight loss and muscle gain, one should be in a small-to-moderate caloric deficit, any more than that and you run the risk of sending your body into a fat saving mode with the added issue of it "eating" its own muscle mass for energy. My own daily maintenance level for calories would be around 3500 at my current rate of activity, I hover right around the 3000 mark currently. Note that it usually takes quite a bit longer to recomposition one's body than it does to bulk it up and then cut fat in separate cycles.

It is not recommended for the underexperiended to attempt body recomposition. That is advanced along timing of macro intake. Keep it simple. 

I've tried a number of different fitness and diet regimens since my metabolism hit a brick wall around 20. Some worked better than others, but in the end I never ended up sustaining any of them long term. The closest I previously came to success was simply controlling portions and strength training at least twice a week; no supplements or any fancy shit. That's probably what I would have tried again before the pandemic hit. Losing work, staying indoors, and doing lots of home cooking caused me to gain a ton of weight in a short amount of time. Decided to recommit when I found that I could barely even put on my good slacks any more.

But what to do in the middle of a pandemic when you love food, hate deprivation, and mostly relied on the gym to stay in shape? After some tweaking it seems that - at least for me - the answer is intermittent fasting. I tried a more extreme version in the past to little success, but this version is doing wonders so far. Basically I don't eat until I get home for dinner and dessert. It's counterintuitive to everything you're told about lots of small meals and breakfast being the most important meal of the day and all that, but it's working great so far. I find my stomach mostly stays 'asleep' and doesn't bother me until I wake it up with food, so putting that off until the end of the day saves me a lot of calories. This way I'm able to eat what I want until I'm full, go to bed sated, and still lose weight. Been doing it consistently for about two months now without issue. We'll see if anything changes when I get lean but so far my cravings are minuscule and I'm much less lethargic than if I were eating normally. It's the easiest diet I've ever been on by far.

I've deliberately avoided constantly weighing myself this time but those same slacks I could barely get on before now barely stay on without a belt. I plan to keep this going indefinitely if possible. I don't plan on going back to the gym until next year but fortunately I seem to be holding on to most of the muscle I gained in the meantime. When I do go back, maybe I'll add an extra meal on workout days to reward and fuel myself. Regardless, I think I've got a system I can actually stick with this time.

It's not immensely complicated, but you do have a point. The caloric deficit should be roughly the same when you're simply aiming for weight loss as well though, a larger deficit will cause problems and won't really help anyone long term. And the contents of the calories matter a whole lot, even when not attempting body recomposition. I'd probably recommend straight up weight loss anyway for someone inexperienced, they would have the added benefit of building muscle really quickly once into the bulking phase.

No scale, probably too bulky for my room.

I eat lunch at work, which can be variable nutrition. I then go home and have a fairly balanced carb, protein, fats meal for dinner. It is barely enough for me to gain weight, so I think if I add a bit more strength training the weight gain will be just muscle. Even if it does make me lose weight, my abs will come back instead.

The pole is like 15-20ft high. It is very sturdy and there are many poles next to it, so if I was weak enough I could use 2 of them. But I am fine with just one.

I need to gain weight. I've been 55 Kg for the last 10 years. It went up to 57 Kg when I was going to the gym but now I'm back to 55 :/

Well, I started to do exercise once again after the last 3 months of quarantine.
While is not as great as a gym, we could still be creative using even furniture to train.
I'm still going to wait a lo more before going to a gym, so better keep doing home routines.

It is healthy to have some fatreserves on top of the gained muscles or your body will fastly turn on cannibalizing the gained muscles if you do not take in the needed nutrients.

Oh, Arny! Its a legend! Also would be interesting if you share his steroid cycle advice...He recommend buy roids in https://steroidsfax.org/injectables-steroids