There's an obesity problem in this country as evidenced by the rise in diabetes, heart disease and weight-related cancers, Jim Cramer said on his

"RealMoney" radio show Wednesday.

"We can wring our hands about it. ... We can say we should eat better food ... or we can make money off of it," Cramer said.

His two money-making plays include one for people who are serious about losing weight and one for people looking for a diet shortcut.

His first pick was

Weight Watchers

(WTW) - Get Report

, a publicly traded company that was once a division of

Heinz

(HNZ)

.

People attend weekly meetings, receive group support and learn about healthy eating. Cramer believes that this is "money in the bank" as people realize that fad diets just don't work.

As dieters realize this, they will go back to Weight Watchers because "behavior modification never goes out of style."

The company is growing at 15%, but sells at 23 times earnings. Cramer said; and he is "always willing to pay twice the growth rate" for a stock. That means if a company is growing at 15%, he will pay 30 times its forward earnings-per-share price.

The play on quick-fix dieters is

Arena Pharmaceuticals

(ARNA) - Get Report

, he said, because the company is developing a diet drug similar to

Wyeth's

( WYE) Fen-Phen that should be safe.

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Cramer described Arena's treatment, APB356, as "Fen-Phen without the heart attacks," but added that this claim is still speculative because the drug does not have Food and Drug Administration approval.

But Cramer believes that as obesity becomes more of a problem, regulators will want to offer something to help consumers struggling with this problem.

A caller who bought

Halliburton

(HAL) - Get Report

on Cramer's recommendation wanted to know if he should hang onto it now that the stock has moved higher.

While Cramer always advocates taking some gains off the table, he said he wouldn't get rid of Halliburton, which he owns for his charitable trust

Action Alerts PLUS.

That's because he believes that the company will spin off its

Kellogg Brown Root

division into a separate engineering and construction firm, leaving Halliburton as an oil services company.

He also said that with the stock near $76, investors are getting the engineering and construction firm for free. He would wait until the stock hits $100 before selling.

Many new investors focus on the actual dollar amount of a stock is in determining whether it's cheap or expensive. "Many of you tend to get into stocks around $10 or lower," he said. While that's fine, those stocks are not necessarily cheap.

That's because whether a stock is expensive or cheap is determined by its price-to-earnings ratio. If a stock has a very low P/E ratio, then positive things about the company and its potential to earn are not factored into the stock price.

And if that is the case, the good news should someday work its way into the price and the stock should go higher.

At a low P/E ratio, you're getting a good stock at a discount.

Limiting buys to stocks under $10 means you could be missing out on fabulous opportunities, he said.

For example, he said that

Goldman Sachs

(GS) - Get Report

is the cheapest of all the brokerage stocks, even though it sells for about $160 a share.

The company buys back stock aggressively and has great growth potential, Cramer said. He added that the company has the ability to earn $15 a share, and if that happens, then the stock should be worth $225.

Even if you only buy one share, that's a huge profit, he said. The dollar amount is high, but the stock is cheap because the price-to-earnings ratio is low.

Sears Holdings

(SHLD)

, which he owns for

Action Alerts PLUS, also seems pricey at $136 a share.

But Cramer doesn't want to sell the stock because it sells cheaply compared with forward earnings. Plus, he believes that the company's great management will create organic growth within the company.

Cramer told listeners that during his early days on Wall Street someone encouraged him to buy

Berkshire Hathaway

(BRK.A) - Get Report

at $200. He decided against it because $200 seemed very expensive.

However, he did not understand that it was cheap relative to all the company's potential upside.

Now Berkshire trades at $90,000 a share, and if he had bought two shares for $400 when he got the call, they would be worth $180,000.

Speaking of Berkshire Hathaway and growth, company Chairman Warren Buffett believes that the best growth is not in the U.S., but overseas.

So he is "selling out a long duration equity index put contract." In plain English, that means Buffett is offering a kind of insurance policy. If you invest in foreign markets and they go down, he will pay for the damage, Cramer said.

Why would anyone do this? If the market doesn't go down, Buffett pockets the premium you pay, he said. It's like fire insurance for your house. It's unlikely that there will be a fire, but you still pay the insurance.

For overseas growth, the directed listeners to Brazil, Russia, India and China.

A caller wanted to know what Cramer thinks of

Dow Chemical

(DOW) - Get Report

, the largest maker of plastics worldwide.

Cramer said that he likes the company for its good management but that the real reason to buy the stock is the fact that natural gas prices have come down.

"In order to make plastic, you need natural gas," he said, adding that Dow was the largest buyer of natural gas in the world. Its bill last year was $20 billion because of how high natural gas prices climbed.

But now that natural gas prices have come down, the company's raw costs have declined. Combine that with the fact that business is strong and that should translate into big profits, he said.

He also likes that the company pays a 3.5% dividend and that a misguided analyst downgraded the stock, which now sits near its 52-week low.

That's your opportunity to buy this fabulous company ahead of what will be a great year, he said.

Cramer always tells listeners to look around at companies they know, do a lot of homework and then make a well-informed purchase.

But, he said, this is not foolproof, because nothing is a guarantee in the stock market.

For example, Cramer bought

Symbol Technologies

( SBL) after reading reports that radio frequency identification (RFID) tags would be used more and more to track inventory.

After reading the articles and doing a lot of research, he chose Symbol. But the stock eventually tumbled because the company's management made their future look rosier than it was.

"There are always people out there who will bag you," he said. No amount of homework will change that.

The lesson is not that research is worthless, he said. One lesson is that the stock market is always risky. The other is that it is important to have a diversified portfolio.

Symbol fell, and the reason it didn't "annihilate" him is because it was just a portion of a diversified portfolio. Other gains offset that loss.

At the time of publication, Cramer was long Sears Holdings and Halliburton.

James J. Cramer is a director and co-founder of TheStreet.com. He contributes daily market commentary for TheStreet.com's sites and serves as an adviser to the company's CEO. Outside contributing columnists for TheStreet.com and RealMoney.com, including Cramer, may, from time to time, write about stocks in which they have a position. In such cases, appropriate disclosure is made. To see his personal portfolio and find out what trades Cramer will make before he makes them, sign up for

Action Alerts PLUS. While he cannot provide personalized investment advice or recommendations, he invites you to send comments on his column by

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