(CBS) After almost two decades, the USDA food pyramid is history. First Lady Michelle Obama today unveiled the USDA's update on America's visual nutrition guide, replacing the familiar - and much maligned - pyramid with a plate.

PICTURES - Bye-bye pyramid, hello plate: Timeline of food guidelines

The food pyramid has been around since 1992, but nutrition experts don't seem to be mourning its demise. 

"It's going to be hard not to do better than the current pyramid, which basically conveys no useful information," Dr. Walter C. Willett, chairman of the nutrition department at the Harvard School of Public Health, told the New York Times.

The new design incorporates seven key dietary messages:

• Enjoy your food, but eat less
• Avoid oversized portions
• Make half your plate fruits and vegetables
• Drink water instead of sugary drinks
• Make at least half your grains whole grains
• Switch to fat-free or low-fat (1 percent) milk
• Compare sodium in foods like soup, bread, and frozen meals - and choose the foods with lower numbers.

 

Experts argued the now-defunct pyramid lumped all types of foods in its design - including unhealthy ones at the top of the pyramid . That made it hard to tell which foods were better choices.