It tastes good. It’s filling. It’s only 80 calories for 2 cups.

It’s a favorite snack for millions of Americans, especially those of us trying to lose weight.

But this low-cal diet snack may also be deadly.

The problem is something called popcorn lung, a potentially fatal health condition that may occur from inhaling the scent of butter-flavored microwave popcorn.

Until now, only workers in the food industry were believed to be affected. Hundreds of workers at food factories have already filed lawsuits because they were exposed to chemicals used to flavor popcorn.

Their lungs have been damaged or destroyed.

Recently, a doctor believed that his patient, a relatively healthy 53-year-old American, had contracted popcorn lung.

His symptoms were progressively worsening shortness of breath and coughing. His ability to exhale was also deteriorating.

But this man didn’t work in the food industry.

Instead, he ate at least 2 bags of extra butter-flavored microwave popcorn every day for several years.

The chemical culprit is diacetyl in the butter flavorings made for popcorn. Heated diacetyl, the same as what you would inhale when butter-flavored popcorn is microwaved, is supposedly the worst.

When this man cooked popcorn, the airborne levels of diacetyl in his home were similar to those in the microwave oven exhaust area at a popcorn factory.

The man’s doctors can’t be sure that popcorn caused his respiratory disease. But his condition appeared to stabilize after he stopped eating microwave popcorn.

The Food and Drug Administration (FDA) is evaluating a warning letter from the man’s doctor. They’re considering the possible safety and regulatory issues involved.

The Flavor and Extract Manufacturers Association is also recommending that its members minimize the amount of diacetyl in the butter flavorings they make.

Until the FDA can determine what happened, you may want to avoid butter-flavored microwave popcorn and substitute other low-cal diet snacks instead.