Beers that are commercially available were altered to add electrolytes while slightly reducing alcohol content,...

Beers that are commercially available were altered to add electrolytes while slightly reducing alcohol content, though the flavor was not affected at all. The modified brews were given to test subjects who had just finished exercising. The light beer was shown to retain best in the body, meaning it was hydrating most effectively.

 Hydrating beer means less chance of a hangover the next day.

Source:http://www.smh.com.au/national/australian-boffins-brew-up-a-hydrating-beer-20130816-2s20b.html