Since we have control over the process and the recipes, I think it is possible to tweak things to come up with a beer that balances flavor and calories. This last summer, I brewed a lot of light saisons using the Wyeast 3711 French Saison yeast. That sucker will take a beer all the way down to 1.000. The great part is to look at what that does to the calorie content of the beer:
A regular pale ale that goes from 1.050 to 1.010 has 5.3% ABV, 163 calories and 15.2 grams of carbohydrates.
A saison that goes from 1.040 to 1.000 has the same 5.3% ABV, but 127 calories and only 6.1 carbs.
That is a 22% reduction in calories with the same ABV.
Unfortunately I didn't lose any weight this summer, but I like to think it helped keep things from getting too much worse.