> I disagree. The biggest health problem is...
You aren't disagreeing, you're making a claim about _the biggest health problem_, while I'm making a claim about _one of the biggest health problems_.
I disagree pretty strongly and can provide as many examples as you would like:
- One of the biggest health problems in America is too much bicycling
- One of the biggest health problems in America is too little automobile travel
- One of the biggest health problems in America is too much space travel
- One of the most nutritious foods is rocks.
I think instead what you mean can be best explained by reading the wikipedia article on weasel words. [1]