Michelle Obama's food campaign shows her stomach for political fight

Their grumbling was sotto voce and neither lobbyist wanted to go on the record, but four years after Michelle Obama began her fight against America's obesity epidemic, her increasingly activist campaign is clearly beginning to get under the skin of the US food industry.

The two corporate executives were sitting in the East Room of the White House watching the first lady unveil the most radical overhaul of nutritional labels in 20 years and could be overheard comparing two versions: one which emphasised even more than the other just how unhealthy processed food can be.

"What do you think?" asked the first exec, glumly. "We like one better than the other, that's for sure," replied the second, complaining that her company had received little advance warning of the proposed changes. "I am getting my head of regulation to run through it all now."

The decision for Obama to front the new rules marks a rare venture into policy-making, but the first lady made clear she was not going to let the niceties of consultation periods and stakeholder dialogue stand in her way.

"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," she told the East Room audience.

"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."

The increasingly strident tone has not gone unnoticed among conservative opponents, where even her early efforts to focus on positive alternatives such as exercise and healthy eating drew scorn.

"Why would you want to raise your own kids when Michelle Obama will do it for you?" columnist Tucker Carlson asked on Fox News when she first launched the Let's Move campaign.

Rush Limbaugh called her "the nutritionist at large", busy "demanding that everybody basically eat cardboard and tofu".

There is no doubt that Let's Move has a messianic side. During an event later that day to promote exercise at a daycare centre in Maryland, Obama was greeted by a fitness instructor who had just accidentally punched a hole in the ceiling in his enthusiasm to rally a class of four- and five-year-olds.

Trying to get a bewildered class to eat celery sticks and hummus for the cameras stretched the persuasive powers of even a charismatic mother of teenage daughters.

But while the passion seems at risk of draining from her husband's second term, Michelle Obama seems to be revelling in an enlarged policy role that showcases both the fiery side of her character and an enviable ability to bust dance moves.

Flanked by actors dressed as "vegetable superheroes" Brian Broccoli, Erica Eggplant and Colby Carrot, the first lady took part in 20 minutes of energetic exercise routines in front of a small group of photographers on Thursday.

Not even the wit of a media-savvy toddler could dent the infectious energy of the room. "Do you know why I am here?" asked Obama. "To take some pictures," shot back one of the girls.

Her blizzard of TV appearances is also threatening to upstage her husband this month, including one interview carried out by president George W Bush's daughter Jenna for the Today show.

During its fourth anniversary week, the first lady's Let's Move campaign is drawing particular energy from recent public health data showing a 43% fall in obesity levels among two- to five-year-olds compared with a decade ago.

Although experts are uncertain of the exact causes, the progress follows a period after the 1970s when childhood obesity trebled in the US. The campaign hopes to help prevent adult obesity levels hitting 50% by 2020 if other trends continue.

The administration's health and human services secretary, Kathleen Sebelius, says the data is a "sign that our efforts are beginning to work", but Obama is more cautious. "We are starting to see some changes but we are nowhere near the end of this road," she says.

Instead, Obama makes it clear that her target is not just persuading consumers but rolling back the power of large food corporations.

"Our kids see thousands of food ads for products loaded with sugar, fat and salt and see on average just one ad a week for healthy products like water, fruit and vegetables," she points out.

"This isn't a particularly radical idea; in fact, it seems pretty obvious. But the truth is that too often, it's nearly impossible to get the most basic facts about the food we buy for our families."

A personal fight of this magnitude and energy looks like it could continue even beyond her second term in the White House.In a week when her husband has outlined plans to campaign for educational opportunities for young African-Americans when he leaves office and vice-president Joe Biden has hinted at running against Hillary Clinton for a presidential nomination in 2016, the current first lady is beginning to display future campaigning potential of her own.