Is it bad to read about politics and world events when fasting..?

There is nothing inherently wrong with reading about politics while you're fasting. However, it's not the best use of your time during such an activity.

The point of fasting is to starve natural and carnal pleasures, and follow after spiritual pleasures instead. Fasting is meant to be a period of spiritual emphasis, where you decrease attention towards secular activities and information, and align yourself to more spiritual pursuits, such as prayer, the study of the Scriptures, meditation, reading Christian books, and similarly beneficial activities.

So, to make the most of your fasting period, try to stay away as much as you can from non-spiritual endeavours so you can devote as much of your time and attention to God as possible, for the best results during your fast.

I can add an exception: if for example, the Spirit of God instructs you to check out some news because of, say, something He wants you to pray or intercede about, for instance - that's also possible. It can certainly be the case - a very specific case, and there would be nothing wrong with that either.

I've just focused on the general purposes of fasting and what's best to do with the time you fast.

God bless you.