Persistently elevated inflation and soaring interest rates have led many investors to flee equity markets. That's why the S&P 500 index has slumped 25% year to date. But even after this sizable sell-off, the index yields just a paltry 1.8%.

The problem with pure income stocks is that they often come with low growth profiles, which can lead to dividend growth that lags inflation. Fortunately, there are some income stocks that allow yield-hungry investors to have their cake and eat it too.

Here are two stocks with dividend yields that are triple the S&P 500 index's payout -- and that also have quickly growing businesses.

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1. Medifast

With 73% of American adults being either overweight or obese, many would certainly derive health benefits from weight loss. But losing weight is obviously easier said than done.

The good news for those seeking to lose weight and keep it off is that there are viable solutions out there. And nutrition and weight loss company Medifast's (MED 4.84%) Optavia weight-loss coaching program certainly fits into that category.

Optavia recognizes that successful weight management stems from the development of healthy, lifelong habits and personalized coaching support, not fad diets. This approach is how the company has grown to more than 68,000 independent, active earning coaches, supporting over 1 million customers each year since its founding in 1981. 

Yet, as large as Medifast has become, there is still lots of room for growth. It's estimated that out of the 155 million Americans who want to lose significant amounts of weight, 95 million will consider paid meal plans and coaching. This is precisely why analysts are anticipating that Medifast will deliver 20% annual growth in non-GAAP (adjusted) diluted earnings per share (EPS) through the next five years. 

As much growth potential as Medifast possesses, what differentiates it from most other stocks is that it also offers income investors a 5.4% dividend yield. For context, this is triple the S&P 500 index's yield. And with the dividend payout ratio set to be around 59% in 2022, this high starting income is well protected. 

The cherry on top is that shares of Medifast can be picked up at a forward price-to-earnings (P/E) ratio of just 11.3. Given that the forward P/E multiple is approximately half of its annual earnings growth prospects, Medifast appears to be an excellent growth stock at a bargain-bin valuation.

2. Iron Mountain

Iron Mountain's (IRM 0.15%) real estate portfolio consists of nearly 1,400 properties, measuring a combined 95 million square feet in size. This gigantic footprint helps the company to serve approximately 225,000 customers in 59 countries throughout the world.

Nearly all companies have the need for records storage at some time, which is how the company generated 64% of its $4.5 billion in revenue during 2021. The consistent demand for records storage and high cost of transferring records to another facility both play a role in Iron Mountain's admirable 98% customer retention rate.

As compelling as the company's storage business model may be, future growth will mostly be driven by its service segment. This most prominently features Iron Mountain's data center business, which has around 1,300 customers. As more businesses migrate records to the cloud, this customer count could significantly expand in the years ahead for Iron Mountain. That's why the high-single-digit adjusted funds from operations (AFFO) per share growth forecast for 2022 should persist well into this decade and beyond. 

Iron Mountain provides investors with a 5.4% dividend yield. And with the dividend payout ratio poised to come in at about 66% in 2022, this market-crushing income is rather safe. Best of all, investors can purchase shares of Iron Mountain at a forward price-to-AFFO ratio of just 12.1. That's hardly a steep price to pay for the company's rock-solid growth prospects.