Did you ever wonder why some packaged products in the grocery store have so much empty space in them?

Consumer Reports’ recent investigation turned up several products with packages that are as much as half-empty. Those include One A Day Men’s 50 + Advantage vitamins, where the plastic 50-tablet bottle looks about 40 percent empty, and Lay’s Potato chip bags that are half-filled.

Over the years, CR has tackled various issues related to product packaging — over-packaging (the so-called “golden cocoon”), hard-to-open packaging (bestowing offenders with an “oyster award”), and now bags, boxes and bottles with what seems like lots of excess or dead space, which CR dubbed “black-hole” packaging.

Relying mostly on nominations from readers, CR rounded up a handful of products and asked the companies behind them for an explanation of all that air to spare. Packages CR looked at are examples of what is likely to be found on store shelves, and don’t necessarily represent the worst offenders out there.

• Post Shredded Wheat. A Post customer-relations representative said that the company can’t overfill because cereal can get caught near the top of the bag, resulting in an improper seal. Post also allows for settling, which varies with size, shape and sugar content.

• Uncle Ben’s Whole Grain Rice. “Rice needs to breathe,” said a customer rep for Mars Food US. She noted that holes in the bag help with respiration. That’s fine, CR answered, but the bags it bought weren’t very holey. In any case, the plastic pouch could accommodate far more grains.

• Ocean Nasal Spray. Why the cardboard partition and extra space? According to a customer rep for Ocean’s maker, Fleming Pharmaceuticals, the company uses the same box for its periodic buy-one-get-one-free promotions, which include a second, smaller bottle. If the company used different-sized boxes, she said, it could create problems in stores, where shelf space is planned and paid for based on a standard package size.

• Mrs. Paul’s Lightly Breaded Tilapia Fillets. Manufacturer Pinnacle Foods declined to provide an explanation, but a customer rep said the extra space helps maintain “product integrity.”

• Bayer One A Day Pill. The plastic 50-tablet bottle looks about 40 percent empty. One customer rep said that maker Bayer HealthCare sometimes gives customers 10 or 15 free tablets. Another cited a need to fit “a lot of information” on the bottle.

• Pasta Roni Garlic & Olive Oil Vermicelli. A customer rep from maker Golden Grain said that the company uses the same-sized box for all of its Pasta Roni products to help keep costs down. He also pointed out that the width of the box matches the length of the vermicelli, cradling the noodles and minimizing breakage. CR was still left wondering why the noodles aren’t stacked higher.

• Pepperidge Farm Texas Toast. This frozen toast was about two-thirds bread and one-third box. A customer rep for the company speculated that the extra space might have to do with “shock absorption and air circulation.” She also mentioned that the product will soon be sold in a reclosable stay-fresh package and said that she presumed the new package would be more efficient.

• Quaker Oatmeal to Go Brown Sugar Cinnamon Bars. Stripped of their plastic wrappers and stacked, the six 2.1-ounce bars leave about half the box empty. One Quaker Oats customer rep called the extra space “crush room” and said that the bags fit loosely to add cushioning and make tearing easier. Another rep told CR that the microwavable bags need room for ventilation.

It was easy to tell that some of the products in CR’s investigation were far from full. To file a complaint, contact an FDA district complaint coordinator in your state. A list is available at www.fda.gov/safety/reportaproblem/consumercomplaintcoordinators/default.htm.