Studies show people underestimate their calorie consumption by an average 30-40%. Obesity has little to do with what kinds of calories people are eating. It's that almost everyone eats way more than they think they do.

Calories in v. calories out still holds. That's one point. If you want to lose weight, you need to be taking in fewer calories than you are using.

The second point is that your body does not process all foods the same. Some foods (high in sugar and carbohydrates) are much easier for your body to process and store as extra energy. Others (fats and proteins) actually require more energy to process, meaning that from the accounting perspective, fewer calories are available for your body to store.

It's not either/or, it's both/and.

Weight loss =/= health.

You might feel shitty if you only eat sugar and starches, but if you eat at a caloric deficit you'll lose weight.

You might feel better if you eat veggies and lean proteins, but if you overeat them, you won't lose weight and, depending on how much, will gain.

But it's just false that to lose weight you need to eat certain kinds of foods.