Manufacturers have been combating the rising agricultural and shipping costs by taking a little off the top. A couple paper towels here, a dozen scoops of coffee there - but they pass those slightly reduced products off at regular price. Over time, the savings can net them millions without customers ever realizing the difference.

And yes, it's perfectly legal. Underhanded, but legal.

The key is in the unit price - something that shoppers who've never hit the Piggly-Wiggly without a calculator should already be aware of. Breyers (UN) recently reduced the weight of their ice cream containers from 1.75 quarts to 1.5 quarts - but the price stayed the same. If your supermarket sold the ice cream for $4.29, that's a change in unit price from $2.45 to $2.86 per quart.

Well, at least they're doing their bit to combat America's obesity epidemic.

But it's not only junk food: PepsiCo (PEP) got into the act by shrinking the large bottle of Tropicana by 7%, thereby reducing the amount of orange juice from 96 to 89 ounces. Customers were tipped off by the bottle's sleek new redesign, which I'm sure the company tried to market as "hip" or "futuristic."

Though eyeballing the item on the shelf won't always work.

Kellogg's (K) showed a wealth of ingenuity -- or was it greed? -- when it reduced the depth of the box rather than height. If the front of the package is facing out, the sides are hidden and no one's any the wiser. Except for maybe the kids who wonder why the prizes inside have gotten so weirdly narrow.

And consumers are already used to a normal bag of chips being mostly filled with air. So if Frito Lay, a division of PepsiCo, adds a bit more space to a bag of Dorito's, very few will notice. But if you ask me, that's the antithesis of "crunchtastic."

Unfortunately, it's not just food and drinks that are getting hit with a reduction ray. Procter & Gamble (PG) shaved a few sheets off rolls of Bounty, Kimberly-Clark (KMB) shrunk the width of Scott tissues, and Clorox (CLX) reduced the amount of sodium hypochlorite -- the active bleach ingredient that makes your whites whiter -- to fit in the fresh mountain smells found in their scented bleach line.

With companies constantly putting their thumb on the scale, customers have very few options for fighting back.

Other than checking for changes in unit price or searching for stray original-weight items still on the shelves, shoppers have to bite the bullet and substitute generic for their favorite brands. So while you may be cuckoo for Cocoa Puffs, you're going to have to learn to be frantic for Fudgie Flakes.