Want to shed weight before you wed? Here's how

Who doesn't want to look their best on their wedding day? Even Prince William and Kate Middleton reportedly are trimming down and toning up before their big day.

So if you want to drop a few pounds for an upcoming wedding or maybe a graduation or some other big event, Cynthia Sass, registered dietitian and author of "Cinch: Conquer Cravings, Drop Pounds and Lose Inches," weighed in on the best way to lose, "The Early Show."

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Pictures: Prince William and Kate Middleton
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Video: Trim down and tone up for your big day

We've all heard that crash diets don't work, but why is it that they fail?

According to Sass, "Going on a crazy crash diet before a big event is actually the best way to look your absolute worst. Because, number one, you could lose muscle mass. You're going to get thinner, but flabby. No one wants that," she says.

There are other side effects that aren't flattering and are downright unhealthy.

"It can also cause your hair and skin to look dull and dry. You're not going to look your best. And it can also weaken your immune system so if you're prone to cold sores, those can pop up," she adds. "Or catching the cold or flu ,so you're going to have a bright red nose on the day of the event. Stay away from crazy, crash diets."

So what can you do?

First of all, Sass suggests that you need to start a month out.

"The number one thing you can do is get rid of the liquid calories. We don't think of them as food, but they can snowball," she points out. "For example if you just got rid of one 20 ounce bottle of cola or sweet tea a day, in 30 days, that adds up to about 2,000 jelly beans worth of sugar that you don't think about."

In terms of weight, Sass says it actually could be a difference between a whole dress size.

"Just getting rid of that one thing. Stick with water, unsweetened tea," she says.

If you are a java drinker, have no fear -- Sass says if you have to have your morning cup of coffee, just put skim milk, a little bit of sugar in the raw and, if you add cinnamon or nutmeg, that will curb your sweet tooth. And it gives you a lot of flavor and aroma, she adds.

As far as food intake, Sass recommends something more balanced.

Believe it or not, Sass says your eyeballs are going to be one of your best assets, because you can visualize your portions and proportions.

"Literally 50 percent of your plate should be covered with vegetables, about a quarter with some kind of whole grain and a quarter with lean protein. If you have some sort of healthy, plant-based fat, like extra virgin olive oil, you cannot go wrong with this proportion," she explains.

"It will help get you more fiber, a good amount of protein and carbs to keep your blood sugar level, and you won't go wrong with the calorie level. Then for breakfast, same exact thing, but swap out the vegetables for fruits -- and make sure you always eat breakfast," she reiterates. "A lot of brides or people getting ready for a big event, they start to skip meals. It's one of the worst things you can do because it will slow down your metabolism and make it harder to lose those pounds."

Is there anything you can do a week before your big day?

According to Sass, you want to get rid of bloaters, which include drinking through a straw, drinking carbonated beverages, chewing gum, and using artificial sweeteners. "All of these things cause you to trap more air in your digestive system, which can swell like a balloon, give you that little paunch that you don't want," she adds. "If you want a nice, flat tummy, eliminate these. Stick with water. Eat smaller, more frequent meals, but think more compact nutrition. Go with something like dried fruit or a mini baby bell of cheese. It will take up less space in your stomach."

The cardinal rule for the actual day of your wedding or big event is not to skip breakfast, because that's one of the worst things you can do in terms of your mood and energy level, Sass points out. "Eat some combination of carbs, protein and good fat. An example of this could be whole grain toast with avocado, maybe with an egg, a little bit of juice. But on the day of the event, we all know we're going to celebrate -- before you have that champagne, put some sort of protein in your stomach. Because if you don't, that's going to hit your brain and, within five minutes, you're going to be tipsy."