The Communist Party’s “clean plate” campaign targets livestreaming extreme eaters, wasteful diners and others amid concerns about China’s ability to feed its 1.4 billion people. Chinese regulators are calling out livestreamers who binge-eat for promoting excessive consumption. A school said it would bar students from applying for scholarships if their daily leftovers exceeded a set amount. A restaurant placed electronic scales at its entrance for customers to weigh themselves to avoid ordering too much.

China’s top leader, Xi Jinping, has declared a war on the “shocking and distressing” squandering of food, and the nation is racing to respond, with some going to greater extremes than others. The ruling Communist Party has long sought to portray Mr. Xi as a fighter of excess and gluttony in officialdom, but this new call for gastronomic discipline is aimed at the public and carries a special urgency. When it comes to food security, Mr. Xi said, Chinese citizens should maintain a sense of crisis because of vulnerabilities exposed by the coronavirus pandemic.

“Cultivate thrifty habits and foster a social environment where waste is shameful and thriftiness is applaudable,” Mr. Xi said in a directive carried by the official People’s Daily newspaper last week.

But like so many top-down orders in China, the vaguely worded directive prompted a flurry of speculation. State news media moved quickly to tamp down panic about imminent food shortages, reporting that China had recently seen consecutive bumper grain harvests and record high grain output.

The edict was also met with sometimes ham-handed measures. The restaurant that offered to weigh patrons in the central Chinese city of Changsha quickly drew a backlash and was forced to apologize over the weekend. “Our intention was to advocate not wasting food and for people to order in a healthy way,” the restaurant said. “We never forced customers to weigh themselves.”