One way to find a hot business idea is to follow the money: Where are consumers spending the most?

If that's your approach, consider Intuit's recently released findings from its Consumer Spending Index. It's based on anonymized and aggregated data from more than 2 million Mint.com (an Intuit-owned budgeting tool) users who have agreed to share their demographic information such as age, gender, income, and location. The index measures spending habits from January 2009 to April 2013 and shows consumer spending is up nine percent from four years ago, and significantly so in certain sectors.

Here's where people are spending their money today, along with several interesting start-ups operating in those hot spaces.

Gourmet Food and Restaurants

Grocery spending is up by 17 percent, partly because of the cost of premium groceries. Intuit found, for example, that Californians particularly like to buy food at more expensive grocers, such as Whole Foods Market. At the same time, spending at "general grocers" is down by three percent.

Restaurant spending is up 11 percent, although eating out is the first thing people eliminate when they want to save money. Folks younger than 36 especially like dining out--they're spending 40 percent more now, compared with several years ago.

A few noteworthy start-ups are taking advantage of the fact that people love good food and the economy is healthy enough to support them buying it.

Alex Lorton and Zach Yungst believe food-tech is one of the hottest trends going right now. In 2010 the duo founded Cater2.me so as to bring gourmet food from farmers' markets and passionate chefs into the office. The start-up connects high quality local food vendors and restaurants with companies that have hungry employees in San Francisco, New York, and Chicago and so far has served more than 500 businesses and worked with over 400 food vendors.

Recent Y Combinator grad Goldbely is a different food delivery concept. The Sunnyvale, California-based company curates gourmet dishes from all around the country and can ship them to you within as little as 24 hours. On the menu: bagels and smoked fish from Zabar's in New York, a cheesesteak sandwich from Campo's Deli in Philadelphia, poche shrimp etouffee from Poche's Cajun Market in New Orleans, among other items.

And SiteApps Mobile is a new free tool that joins Open Table and Google in helping restaurants create a mobile-compatible website that includes a description, phone number, address, Google Maps view, and hours. São Paulo, Brazil-based SiteApps says nearly half of consumers say they would use a restaurant's mobile site if it existed. The trouble is, only a small percentage of independent restaurants have a mobile-optimized site.

Think you might want to start a company that can take a bite out of the food industry? Here are 10 reasons it's the next big thing in business.

Gasoline

Intuit says people are shelling out close to double for gas compared with fuel expenditures back in 2009. Specifically, Americans spent an average of $198 a month on gas in the first quarter of 2013. In Q1 2009, that figure was only at $110 a month.

The good news is there's a gadget that will soon hit the market that promises to save you money at the pump.

The Automatic Link is a company that makes an iPhone app that works with a little piece of hardware to monitor your driving habits. The device doesn't come out until July, but you can pre-order one now at Automatic's website for $69.95. The company says its technology can save you between 30-35 percent in fuel costs just by training you not to do things like accelerate too quickly, drive too fast, or brake abruptly.

Healthcare

How the Affordable Care Act--a.k.a. Obamacare--will affect insurance premiums remains to be seen, but spending on healthcare has skyrocketed by an average of more than 30 percent. Intuit says people between 41 and 55 years old spend more than $300 a month on healthcare, but younger folks are actually seeing the biggest increase in health-related costs. People between the ages of 26 and 31 now pay an average of $252 a month on healthcare, compared with $179 a month in the first quarter of 2009. That's an increase of more than 40 percent.

One notable start-up working to reduce healthcare costs is New York-based Audicus, an online seller of affordable hearing aids that range from $299 to $699. Those are incredible numbers considering hearing aids can run into the thousands of dollars. In fact, the company says since launching 10 months ago it has saved customers more than $1.5 million and grown to a run rate of more than $1 million a year.

Kinsa, another New York start-up, is currently well on its way to a successful crowdfunding campaign on Indiegogo. Its first product is "the world's smartest thermometer," a slim device that doesn't have a battery, display, or processor, but instead harnesses the technology in your smartphone. The Kinsa Smart Thermometer and the free accompanying Kinsa mobile app let you track an illness history to share with your doctor, find open appointments at nearby clinics, and see on a map where the most people are coming down with fevers. The idea is that if people are more informed about what sicknesses are going around they will be better able to avoid them.

There's also HealthTap, an online and mobile platform through which you can ask a network of 35,000 doctors medical questions for free. You can follow questions and answers that relate to specific medical concerns, follow the answers given by particular physicians and even store and share medical documents with your doctor in a private and HIPAA-secure conversation.

Esther Dyson is one prominent angel who has invested in HealthTap. Check out why she says healthcare start-ups are the next great innovators as well as 17 game-changing health start-ups.

Gender Differences

It turns out that men spend $600 to $700 more a month than women, specifically on things like alcohol, entertainment, eating out, and gas. However, women outpace men by 21 percent when it comes to spending on clothes and apparel.

That said, if you're thinking about gender-specific marketing, a recent Nielsen report says "women will control two-thirds of the consumer wealth in the U.S. over the next decade and be the beneficiaries of the largest transference of wealth in our country's history."

If you want access to the dollars females are spending, video is a great medium in which to invest. Compared to men, U.S. women watch more video and spend more time online, representing the majority of visitors to career, shopping, and social media sites.

Nielsen also gives advice on how marketing should be slanted to resonate with women. The research firm advises:

"Women remember more and differently than men do, so talk to both her emotional and rational sides and acknowledge her attention to detail. Layering emotional decision-making opportunities with rational information will increase purchase intent and will have strong 'sticking' power. According to Nielsen NeuroFocus, the female brain is programmed to maintain social harmony, so messaging should be positive and not focus on negative comparisons or associations."

Giving

As a true indication that the economy is recovering, Intuit found that Americans have become 47 percent more generous than they were in 2009, specifically when it comes to buying gifts and making charitable donations.

One notable start-up in this space is Wrapp, a social gift-giving app that lets you give free and paid gift cards to Facebook friends. The free gift cards typically are for a few dollars to spend at retailers such as Gap or Sephora and if you want, you can add more funds onto them to make it a more significant gift.

Wrapp, which is headquartered in Stockholm, Sweden but staffs an office in San Francisco, now boasts more than a million users.

Read more about why social gifting is hot on Facebook.