Nutrition is more important for beginners and beginner-level trainees.
I think a beginner is self explanatory, but what is "beginner-level"?
I consider "beginner-level" to be someone who may have embraced a healthier lifestyle, but chooses to stay in their comfort zone. There's nothing wrong with that at all, either. These are your group exercises fanatics, weekend warrior OCR or 5k enthusiasts, or people who simply like waffling around the gym a few times a week.
They're staying healthy, but not really pushing their work capacity. Despite their favorite classes being ticketed as burning 1000 calories, the truth is that most people simply don't have the work capacity to burn that many calories in an hour.
To put it in perspective, let's say out of that class, you're going hard for 50 minutes to allow for warmup, small breaks, and cool down/stretching. A study found the average male burns about 105 calories per mile ran; the average woman, 91 calories. Let's run with an average of 100 for this scenario.
So, for the average runner, you would need to run right around a 5min/mile pace for 50 minutes to have to work capacity to burn 1000 calories in 50 minutes. This is an elite level runner.
If you still think you're approaching that type of work during your extreme dance cardio workout, I've got some beachfront property in Arizona to sell you.
The calorie is a measurement of energy. It's your fuel. How much fuel you need depends on the size of your engine.
If your engine runs on walks by the beach, 5-10 pound Dumbbells, and dancing your way to a slimmer you, it doesn't need a lot of fuel. Enjoy the salad bar. And stop drinking all that wine.
There are two ways to make the engine bigger: Build muscle or do more work.
Actually, there are three ways. The fatter you get, the more fuel your engine needs to carry the load.
Let's stick with the first two. Both are achieved through progressive training. Run faster, lift heavier, jump higher, repeat.
Your body will consistently be changing, requiring more food. It's pretty simple.
Someone who needs 3500 calories per day to feel completely charged has more options than someone who needs 1800 calories.
As a fitness professional, I see the difference at workshops and seminars.
When I go to the more intense, higher level seminars, we often indulge in burgers, beer, pizza, and shenanigans afterwards. The word calorie is not mentioned.
When I've been to group ex workshops, every time they tell you where the nearest Whole Foods or Souper Salad is, and I hear the "C" word.
At the end of the day, one approach is not better than the other, just know which category you are in.
If your body only needs the salad bar, and you're slamming burgers like an elite powerlifter or eating cereal like a Boston qualifier, you're probably not going to see the results you're looking for.
Likewise, if you're trying to be an athlete and truly push your limits while fueling like a rabbit, you're going to live in a constant fog.
Eat like you train!