If you’re following the South Beach Diet, then it’s unlikely that the eggs you purchase are sitting around for long in your fridge. Nevertheless, it's useful to know whether your eggs are fresh.

Here's a handy way to tell: Place an egg at the bottom of a glass full of water and watch what happens.

• If the egg lies at the bottom on its side, it's fresh.
• If the egg sinks, but with one end up, it's getting old but is still edible.
• If the egg floats at all, you should buy some fresh ones.

This test is effective because eggshells are porous — over time they dry out, letting air in and moisture out. If you prefer using egg whites, then save some time and money by buying eggs in bulk and separating them right away, or purchase egg whites in a separate carton at the grocery store. Egg whites freeze very well for up to a year and can even be kept for up to three or four days, covered, in the refrigerator.

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