It isn’t because of the calorie content. If you have a high sugar diet WITHIN the context of a calorie deficit, you will still lose weight.
BUT, foods should not be simplified down to calories alone.
Plain boiled potatoes are significantly more satiating (filling) than sweets.
Try and eat 500 calories of plain potatoes then on a separate day eat 500 calories of sweets. The level of difficulty will be significantly higher for potatoes.
Based on research on the satiety index, food volume, water content and fibre all appear to play a role when it comes to how filling a food is (swipe to see). So, I think it is a massive disservice to describe foods based on macronutrients alone i.e. “protein is more filling than any other macronutrient”, “carbs make me hungry” etc.
When it comes to weight loss, calories will always be the most important factor, of course.
But most people wanting weight loss would likely benefit from revolving their diet around whole, unprocessed foods both from a health perspective and an appetite perspective.
Yes, calories are important.
Yes, food source is also important.