As someone who's currently on a calorie-restricted diet, yes, hunger is a big problem.

However, eating fewer calories by cutting out grains is not the same thing as being on a calorie-restricted diet.

Isn't it automatically a calorie-restricted diet if you are eating fewer calories than you normally would?

FWIW I also have cut out grains but my weight is very stable, so it seems fair to assume I now just eat more of other things.

Define "normally would", because people's calorie intake varies from day to day. Also, previously I claimed that people have a tendency to eat more than they should, so scaling back on that isn't calorie restriction, it's just the absence of extra calories.

More generally, it's just a bit pedantic to say that eating fewer calories than you would otherwise should be called a "calorie-restricted diet". The first reason is because the phrase "calorie-restricted diet" implies a significant restriction instead (for example, I'm only 1200 calories per day right now; that's a significant restriction compared to what I would be eating if I wanted to maintain my current weight). The second reason is because "calorie-restricted diet" implies a diet focused around tracking calories. Cutting out grains isn't a diet focused on calorie intake (heck, it's not tracking calories at all), it's just a diet that has the side effect of likely reducing calorie intake.