How do Claw Tails have so few calories?

Not sure how many of you all have tried the new Claw Tails from White Claw. These are seltzer cocktail mixes that I personally enjoy a lot. They a right balance of sweet and are 7% ABV.

It’s hard to find much extra info on these, but it seems like they are 150 calories per can. In contrast, the standard White Claw is 100 calories at 5% calories per can. Here’s the weird thing though: Claw Tails are significantly sweeter than white claws. ~40 of those extra 50 calories (compared to White Claw) should come from the added 2% alcohol. How is it that so much sweetness is obtained with just ~10 extra calories. Importantly, they claim that there are no artificial sweeteners used.

Anyone else wondered about this?