Alternate Decoction Mash Purpose

TroubleShooting

David Corr — Centerville, Ohio asks,

I’m a bit confused, and I am hoping you can help. I read an article on how Sam Adams uses decoction mashing to make their light beer. The article stated the idea is that enzymes are destroyed during the decoction process to lower the concentration of fermentable sugars, which in turn lowers both ABV and calories. I also read that decoction mashing helps to destroy the cell walls and makes the starches more accessible to the malt enzymes. To me, more starch would result in more fermentable sugars and thus increase the ABV. This seems to contradict what is said above. What am I missing?