This video from Consumer Reports states the products are shrinking in a deft attempt to fool the consumer.
Products require huge production runs to achieve the lowest cost per unit. Also, these products have a huge amount of substitutes. For a manufacturer to shrink the size of their product would require a change in plant size which infers an elastic supply curve. I doubt this is the case for orange juice and toilet paper. Consumer Reports shows that the size of Scott's toilet paper is 12% less which is solid empirical evidence. But to generalize it to create hysteria and sell magazines is unethical reporting.