No matter where you stand on New York City mayor Michael Bloomberg’s proposed ban on the sale of large soft drinks, you have to admit that the proposal has kickstarted the discussion around obesity.

The problem is certainly a serious one: according to the Centers for Disease Control (CDC), 35.7% of Americans are now obese. That amplifies the risk of a range of serious health conditions, including heart disease, stroke and diabetes.

From a financial point of view, cutting the obesity rate also makes sense. According to the CDC, obesity-related medical costs hit $147 billion in the U.S. in 2008, with obese people running up $1,429 more in medical expenses during the year than more fit Americans.

Michelle Obama Puts Her Popularity to Work

At the other end of the spectrum from Bloomberg’s heavy reliance on government regulations is Michelle Obama’s Let’s Move! program. The First Lady has been working on the initiative, which aims to combat childhood obesity and promote more nutritious food for kids, for the past two years.

Let’s Move! encourages healthier lifestyles in a number of ways. For example, the First Lady recently hosted a “kids’ state dinner,” in which she invited children who had participated in a healthy recipe contest to dine at the White House. The event also included a surprise visit from the president himself.

Mrs. Obama has also been making an effort to set a good example herself, recently revealing that she rises at 4:30 a.m. to work out—leaving the president snoozing in bed—so she can be back before their two daughters wake up.

It’s easy to dismiss such efforts as empty public relations ploys, but before you do, consider the First Lady’s sky-high popularity ratings. In May, Gallup found that 66% of Americans had a positive impression of Michelle Obama—a rate that’s held steady for the past two years. That was far ahead of the president’s 52% rating.

Corporate America also seems to have taken notice: Last year, Wal-Mart (NYSE: WMT) joined the Let’s Move! campaign, rolling out a five-year plan to make its food healthier and cheaper. Other companies, such as Walgreen (NYSE: WAG), have also signed on.

Two Stocks That Will Profit From Thinner Waistlines

There are a number of ways investors can cash in on the trend toward healthier eating. Here’s a look at two companies that are on the leading edge: one dominates the niche health-food retail market, and the other is a diversified food maker that’s launching a steady stream of new, more nutritious products.

Whole Foods Market (NasdaqGS: WFM) operates a chain of 328 grocery stores that focus on organic and perishable items. The stores’ produce sections are thought to attract roughly half of the company’s customers.

Whole Foods is about to set off on an aggressive expansion, with the goal of tripling its size to around 1,000 stores. A big part of its plan involves locating new stores in “food deserts,” or parts of the U.S. that are vastly underserved by grocery retailers.

The country is rife with food deserts, from small towns to the cores of major cities. For example, Whole Foods recently announced that it will open a store in downtown Detroit—a place long bereft of good grocery options due to its ongoing economic woes.

Of course, there are risks inherent in this strategy. For one, it’s unclear whether moving into underserved areas—where incomes are typically lower than in places with more food options—is a good move for a high-end grocery chain. In addition, the expansion will mean Whole Foods will be more directly competing with major food retailers like Kroger (NYSE: KR) and Safeway (NYSE: SWY). And as mentioned, general retailers like Wal-Mart are also expanding their healthy food offerings.

As well, the stock is up 65% in the past year and trades at a high p/e ratio of 41.5. That means it will have to keep aggressively growing its profits to continue boosting its share price. So far, that hasn’t been a problem: it just notched its 13^th consecutive quarter of earnings and sales growth, with net income jumping 32% and revenue up 14%.

Still, the company’s expansion looks well thought out. In Detroit, for example, it’s locating its store near Wayne State University and the College for Creative Studies. That fits with its plan to set up shop in areas with more educated populations. And it is also developing scaled-back stores to serve smaller communities.

For a more diversified play on healthier food, look to PepsiCo (NYSE: PEP). At first glance, the company’s connection with more nutritious food isn’t exactly clear: It’s the world’s leading maker of snacks and the second largest producer of food and beverages. Aside from Pepsi, its brands include Frito-Lay, Gatorade, Ruffles and Aquafina bottled water.

However, as Todd Johnson recently pointed out in a June Investing Daily article, about $13 billion of the company’s $60 billion of annual revenue now comes from healthy products, such as oatmeal, which it sells through its Quaker Oats brand, low-sodium snacks, low-sugar juices, seeds and nuts.

As Johnson notes, the company also has several other nutrition-related goals, such as:

• cutting saturated fat in its food products by 15% by 2020;
• cutting added sugar and sodium in beverages and foods by 25% each by 2020; and
• increase fruits, vegetables, seeds, nuts, whole grains and low-fat dairy products

To build its market share, PepsiCo is boosting its advertising spending and rolling out new products. For example, its Pepsi Next drink has half the calories of regular soda. It also continues to expand overseas. To control its costs and improve its productivity, it’s undergoing a restructuring that involves laying off 3% of its workers.

In PepsiCo’s latest quarter, its profits slipped to $0.94 a share from $1.17 a year earlier. Without unusual items, the company earned $1.12 a share, topping the Street’s expectation by $0.03. Sales dipped 2%, to $16.43 billion.

PepsiCo’s wide range of businesses help steady its revenue. That, in turn, lets it pay an attractive dividend: Quarterly payments of $2.16 a share yield 2.95% on a yearly basis.

The company’s stock has been steadily moving higher in the past year, rising about 15%. But PepsiCo’s new products, its ongoing shift to healthier foods and its well-established overseas businesses give it lots of room to keep growing.

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