Seems like there's truth in both points above. In theory, "Calories in vs. Calories out" makes perfect sense and it's not a bad principle to follow for anyone just beginning
to take control of their nutrition. You will lose 'weight' if you create a calorie deficit. But a person whose usual caloric intake of 1,600, all made up of twinkies, peanuts, and nachos will DEFINITELY NOT look, feel, or be as healthy as one whose caloric intake of 1,600 is made up of veggies, fruits, lean proteins, some whole grains and healthy fats.
But there truly is no one-size-fits-all plan, as Tandoori mentioned. Monitor your energy levels throughout the day to see whether your macronutrient choices and portions give you a boost or make you want to crawl up on the sofa. For me, that's a great indicator to know if what I'm eating causes me to thrive or dive. Oh yes, don't forget your water