For the first time in more than two decades, the White House and the Food and Drug Administration unveiled major changes to the iconic and outdated nutrition facts label found on most food packages.

The new label was announced this morning by first lady Michelle Obama at an event marking the fourth anniversary of her Let's Move! Campaign to combat childhood obesity.

"As consumers and as parents, we have a right to understand what's in the food we're feeding our families. Because that's really the only way that we can make informed choices - by having clear, accurate information," Obama said at a White House ceremony. "Our guiding principle here is simple: that you as a parent and a consumer should be able to walk into a grocery store, pick an item off the shelf, and tell whether it's good for your family."

New Nutrition Label Cheat Sheet

The way Americans consume food has without doubt changed dramatically in the past 20 years and the proposed label changes are designed to reflect those changes, be easy for consumers to understand and be based on the latest scientific information. The changes will have a broad sweeping effect as the rule, when finalized, will affect all packaged foods except certain meat, poultry and processed egg products, which are regulated by the U.S. Department of Agriculture's Food Safety and Inspection Service.

The new proposed label changes have been in the works at FDA for more than a decade. The last time any change was made to the label was 2006, when the inclusion of trans fat became a requirement.

"I know there will be many opinions on what this label should look like, but I think that we all can agree that families deserve more and better information about the food they eat," Obama said. "And it's important to note that no matter what the final version looks like, the new label will allow you to immediately spot the calorie count because it will be in large font, and not buried in the fine print. You'll also learn more about where the sugar in the food comes from…This is what you will get from the label of the future."

Here are some highlights:

Calories

"Calories" appears in a larger font, and the number of calories is even bigger and bolded. Mike Taylor, FDA's deputy commissioner for foods and veterinary medicine, said the idea was to make calories more prominent in hopes of emphasizing parts of the label that affect obesity, diabetes and heart disease.

Serving Size

The new label will update serving size requirements to reflect the amounts people actually eat. Ever notice how a 20-ounce soda bottle will say 2.5 servings, even though you drink it in one sitting? The proposed rules now call for it to be considered one serving. A serving of ice cream will also increase from ½ cup to 1 cup, which reflects how much people eat and drink today. FDA has stated that, "By law, the label information on serving sizes must be based on what people actually eat, not on what the 'should' be eating." This will cause the number listed under calories to go up, too. Visually, servings per container also appears larger and bolder on the label.

In addition, the FDA is changing serving sizes on 27 of 157 foods for which there are serving sizes. Some serving sizes will increase, while others, like a single serving of yogurt, will go down. One serving of yogurt will go to 6 ounces from 8 ounces, which reflects the typical size of a single-serving yogurt container. Others that will see their serving size double include breakfast foods like muffins, bagels and toaster pastries. Before a serving size was half of the item, now it will be the whole thing.

FDA has also proposed adding an additional 25 food categories that simply didn't exist decades ago. Some of those items include pot stickers, won ton wrappers, sun dried tomatoes, carob powder, almond milk and some seasonings and oils.

Sugar

Sugar is listed under carbohydrates now, but there will be a new subcategory under sugar called "added sugar." Added sugars are sugars not naturally occurring in food. Experts suggest eating less added sugar because they increase calorie intake and prevent people from eating foods that are good for you.

"I think there are things in the labeling that consumers will find much easier to understand," said Marion Nestle, professor of nutrition, food studies and public health at New York University. "They'll certainly get the calories issue more easily and the business about added sugars is absolutely terrific. People have always wondered how much sugar these companies are putting into these products, now they're going to know."

Total Fat

Many kinds of fats are now listed on the panel (total, saturated, trans, monounsaturated, polyunsaturated). The only change to the fat listing on the label is that "calories from fat" will no longer be required on the new label because research shows the type of fat is more important than the amount.

Vitamins

Vitamins A and C will no longer be required to be listed but vitamin D and potassium are being added because data shows people aren't getting enough of these two vitamins, especially because they are "nutrients of public health significance." Vitamin D is important for bone health and potassium affects blood pressure, among other things. Calcium and iron will continue to be required.

Daily Values

The daily value for sodium is being adjusted to 2,300 milligrams a day from 2,400. Daily values for dietary fiber and vitamin D are increasing. The recommended daily amount of vitamin D is now 400 international units (10 micrograms), but the proposal calls for it to double to 20 micrograms. Dietary fiber values are increasing to 28 grams from 25 grams.

As for the aesthetics of the label, it is also getting a new look. Consumers won't be able to miss the new large size of calories and serving per container but they'll also see "Daily Values" shifted to the left of the label to draw eyes there first. The footnote that you're used to seeing that explains daily value is also being revised to explain it more clearly.

Nutrition label laws were last changed in 1990, and the labels themselves actually changed in 1994, when the focus was on diet related diseases, like heart disease, stroke and cancer. The way Americans eat has obviously changed pretty dramatically since then, and the FDA admits that "much of the information currently provided on the Nutrition Facts … label is based on old reference values and scientific information."

Industry groups applauded the announcement, acknowledging that "diets, eating patterns and consumer preferences have changed dramatically."

"For 20 years, the Nutrition Facts panel has been an invaluable tool to help consumers build more healthful diets for themselves and their families, and the time is right for an update," the Grocery Manufacturers Association said in a statement. "We look forward to working with the FDA and other stakeholders as these proposed updates to the Nutrition Facts label make their way through the rule making process."

The FDA estimates it will cost the food industry $2 billion to implement these changes, but also forecasts a $20-30 billion public health benefit. Once the label is announced later this morning, FDA opens the proposed rules up to 90 days of public comment and what is often a lengthy review and implementation process, meaning consumers may not actually see any changes to nutrition labels in grocery stores for years.

ABC News' Mary Bruce contributed to this story.