You can reduce the weight of the paper without the pages getting thinner. This is one of the benefits with high bulk. A paper with high bulk also has sturdier pages and better opacity than a paper with low bulk in the same grammage.
What is paper bulk and why is it a benefit?
Bulk is the reverse of density. It describes the volume of one gram of a substance. This measurement is really useful when comparing papers.
Lower weight, lower cost, less climate impact
Keep the thickness of the paper and lose weight. With a high bulk paper you can keep the same thickness and still get a lower grammage. But how much less can the paper weigh and still feel as thick?