It's that time of year when everyone makes New Year's resolutions.

Of course, you could make a resolution about anything but there are certain themes that seem to be most popular this time of the year and they usually involve personal growth in some way.

The most popular New Year's resolutions usually involve health and fitness. Whether it is vowing to lose ten or twenty pounds or simply to eat "healthier" or to get in shape in some way, gyms across America will be packed over the next two weeks and people will be shopping for healthy food and trying new diets.

Did you know that January is the busiest month of the year for the online dating sites?

It's also the month when the most people file for divorce.

Yep, apparently there IS a correlation there.

According to the experts, many people wait until the holidays are over to make changes in their love lives because they don't want to rock the boat during all the holiday celebrations. Once those holidays are over, there are break-ups and people are ready for someone new.

Finding love is a popular New Year's resolution.

Cash in on Everyone Else's Resolutions

For investors, there are some great ways to cash in on these New Years resolution trends, if you know where to look.

The #1 New Year's Resolution: To Lose Weight

For weight loss companies, January is their Super Bowl. It's the biggest quarter of the year.

But they have faced stiff competition from wellness devices like FitBit which aren't selling diets, but overall health.

Two of the biggest names in weight loss are Weight Watchers International, Inc. and Nutrisystem Inc.

Weight Watchers (WTW - Snapshot Report) was in a downward spiral in 2015. Earnings are expected to fall 64%.

But in October, Oprah Winfrey announced she had taken a 10% stake in the company and would be the new spokesperson.

It seems that Oprah has already begun to weave her magic because Humana, which has a partnership with Weight Watchers, saw a 19% spike in enrollment in its Weight Watchers program in the month that Oprah made her announcement.

The first advertisement featuring Oprah has also made its debut. It's a doozy, and apparently bringing people to tears.

Analysts believe the company is poised for a turnaround. Earnings are expected to rebound by 16% in 2016.

Weight Watchers is a Zacks Rank #2 (Buy).

Nutrisystem (NTRI - Snapshot Report) delivers meals right to your home. It uses celebrity endorsers, such as Dan Marino and Marie Osmond, to entice new customers.

The company recently bought the South Beach Diet Plan for $15 million. The South Beach Diet was all the rage in 2003 and the book became a big bestseller. Nutrisystem intends to relaunch the diet to a new generation.

Unlike Weight Watchers, however, Nutrisystem hasn't been struggling. Revenue rose 16% in the third quarter.

Earnings are expected to rise 44% in 2015 and another 18% in 2016.

Nutrisystem is a Zacks Rank #3 (Hold).

Healthy Eating Picks Up Steam

It's not just dieting that is big around New Year's anymore, it's also about just eating healthier. Many consumers are choosing to do that by buying organic foods, which have become more prevalent in many more locations.

The WhiteWave Foods Company (WWAV - Snapshot Report) has been riding the momentum in this category. It produces Horizon Organic Milk, Wallaby organic yogurts and kefir beverages as well as Silk brand dairy-free beverages and yogurts.

The organic and dairy-free categories have been especially hot.

WhiteWave just reported a record third quarter as net sales rose 17%. It also raised full year EPS guidance.

Analysts see 2015 earnings growth of 17.5% and another 18.8% in 2016.

WhiteWave is a Zacks Rank #2 (Buy).

The Fitness Craze

Gyms have been around forever, but the workouts are becoming more sophisticated and specialized. Fitness is now a hot investing category.

In 2016, SoulCycle, the stationary-bike workout phenomena, is expected to go IPO. It wants to be more than just a gym, however, as it also sells clothing and it has branded itself as being in the business of changing lives.

SoulCycle operates in upscale markets. It recently expanded in Chicago and has opened in the hottest, trendiest neighborhoods as its classes aren't cheap.

At the opposite end of the spectrum is Planet Fitness, Inc. (PLNT - Snapshot Report). It charges a flat fee $10 a month membership and there aren't any classes.

It's famous for providing free pizza on the first Monday of every month and for being a gym for the regular joes.

Whatever it's doing seems to be working. In the third quarter, revenue rose 8.4% with system-wide same-store-sales up 6.9%.

Planet Fitness is growing at a quick clip. In 2015, it expects to open between 192 and 197 franchise-owned stores and 3 corporate owned stores. Most of its 1,000 stores are owned by franchisees.

The shares aren't cheap, though. Planet Fitness trades with a forward P/E of 30 but analysts forecast earnings to rise 16.6% in 2016.

Planet Fitness is a Zacks Rank #2 (Buy).

Looking for Love

Singles are tired of being single by the time the new year rolls around so finding love is often one of the top New Year's resolutions.

According to the top online dating sites, the most popular day of the year is the first Sunday after New Year's, which, this year, will be Sunday, Jan 3.

That's because everyone has returned from their trips, vacations and obligations to visit family and friends. They are sitting at home on that Sunday night, with the first full week of the new year ahead of them, and they are optimistic that this could be the time to find a new partner.

Match Group (MTCH - Snapshot Report) went IPO in November 2015 as it was spun-off from IAC. It operates 45 different online dating brands, including three of the biggest and best known brands including Match.com, OkCupid and Tinder.

It's so new it hasn't even reported earnings yet as a public company. Most people are excited about the company because of its popular Tinder app.

Analysts expect earnings to grow 14.5% in 2016.

It's a Zacks Rank #3 (Hold).

Keeping Your New Year's Resolutions

While most New Year's resolutions fall to the wayside within weeks of January 1, that doesn't mean that these trends do.

Fitness and wellness have taken hold year round, so much so that people are even doing wellness vacations.

And looking for love will never go out of style even if there are new ways in which to do it.

As an investor, all of these companies offer an easy way to get a piece of these booming trends. What better way to start off the new year than by buying some stocks?

Happy New Year!