For Sam Calagione, a founder of the craft brewery Dogfish Head, his company’s efforts to get healthier had a selfish origin.

“I started to notice that I was getting an everything bagel on my midriff,” said Mr. Calagione, attributing the weight gain to the multiple beers he drinks daily for work. “So I was like, well, I’m not going to slow down drinking, so I better start innovating some lower-calorie but super flavorful beers.”

In 2016, the brewery, which is based in Delaware, began producing its 140-calorie sour, SeaQuench Ale, which it promoted as “the most thirst-quenching beer Dogfish Head has ever brewed.” Now, Mr. Calagione forecasts that of the 300,000-plus barrels of beer the brewery will produce this year, more than a quarter will cater to the demands of consumers more concerned with maintaining active lifestyles than they are with hops or high alcohol content. One beer is a new I.P.A. with fewer calories than a Bud Light.

The craft beer market has expanded rapidly over the past decade, as breweries across the United States have dreamed up whimsical and inventive beers, often with unconventional ingredients — Beet sugar! Jalapeños! — along with high calorie counts and elevated A.B.V. (alcohol by volume) figures. The same breweries are now looking to make products similar to one they have long ignored and even scorned: watery, light beer.