In the second sentence, the a is required. It's wrong to omit it. And no, it has nothing to do with American vs. British English. It's just plain old standard, correct English. And you may rest assured I am native speaker.1. [He] stands a little shorter than 1.7 meters tall but weighed 111 kilograms.
2. He now weighs a mere 79 kilograms.
3. The son weighs 90 kilograms.
I consulted a couple of dictionaries, and I didn't see example sentences put like the second one.
Is the "a" in the second one optional? Or is it of an example of the differences between American English and British English? Or else?