Actually you want to have a little head (lol and who doesn't?) as this helps release a few gas bubbles unto the atmosphere before they get filtered through your digestive system. Pour the first two inches of beer slowly onto the side of a tilted glass as J suggests then plop the rest down the center; this will leave you plenty of bubbs in the beer.
Believe me I can drink fast. I notice that on my favourite glass a little emblem on the inside of the base appears to produce “bubbles”. I dropped this glass last week, could this have anything to do with it?
If its your own glass then try not to wash it with soapy water. It stops bubbles occuring. Just give it a good rinse with hot water.
As for the reason behind the head. When you poor, the beer creates swirls (under currents) in the glass and this mixes any remnants of yeast together thus creating the froth. If you poor slowly the swirl is no where near as harsh as a fast poor. (just have a look next time u poor a beer)
1) get a clean smooth glass
2) get a carlsburg (my fav)
3) open beer
4) tilt the glass 45 degrees
5) slowly tilt the beer so it runs against the side off the glass from the very top.
6) when the beer in the glass fills up so it's about 2 flow out were the can + the glass join tilt the glass upright + pour rest of beer from a height of aprox 5cm.
7) drink and repeat from step 2