This is one rule of thumb we'd like to never speak of again. Because life's too short for foodborne illness.

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If using food thermometers while cooking could prevent many of the 48 million cases of foodborne illness each year, why aren’t we using them?

Yaohua "Betty" Feng, an assistant professor of food science at Purdue and Christine M. Bruhn of the University of California, Davis, analyzed 85 studies from over two decades to understand current attitudes and behaviors associated with thermometer use. Despite it being widely accepted as a best practice in home and professional kitchens, thermometer use is extremely low. Of the two-thirds of people who reportedly own a meat thermometer, less than 20 percent actually use it to check the temperature of chicken, and less than 10 percent use it all the time for hamburgers.

In their research, Feng and Bruhn found that one of the key reasons most home cooks don't use food thermometers is that many public-facing food figures—celebrity chefs, restaurant managers, cookbook authors, food bloggers—rarely take temperatures to signify when a dish is cooked completely. Instead, they tend to rely on visual cues, like browning or grill marks.

The only thing worse—especially for inexperienced cooks—is using that disturbingly unreliable “poke test." You know the one I'm talking about, right? When someone excitedly holds out their hand and pokes the area between their thumb and index finger, claiming that the softer, fleshy skin area is “equivalent” to rare and the firmer area closer to their wrist is well-done? I've seen people also push their thumb against their index, middle, and pinkie finger to express the different levels of doneness of meat, too. The idea makes me cringe.

News flash: this trick is a complete sham and can lead to foodborne illness. Why? Because it suggests that you can kinda-sorta guess when your meat is cooked, therefore making a food thermometer obsolete. This is a surefire way to put you and your family at risk of infection. Bacteria naturally exists in raw meat, and the only way you know you've heated your steak to a sufficient internal temperature to kill this bacteria is by taking its temperature.

Poke test ends today, folks. If you're a novice cook in need of an easy way to check for doneness, that's completely okay—you just have to get (and use) an instant read thermometer instead of trying to compare your steak to your palm. It's a no brainer so we'll say it again: taking a piece of meat's temperature is the only way to make sure it's been cooked enough to eliminate potentially harmful bacteria that could make you and your family very sick. Instant reads are widely available and super affordable—we love this $10 thermometer from Taylor Precision—and they take the guesswork out of searing, grilling, or roasting meat.

Check out this handy temperature guide before you fire up the grill this weekend. Actually, you should probably print it out and keep it in your kitchen.

I mean just think about it… what is the likelihood that your hand feels the same as the hand of someone twice your size or half your age? Just sayin’.