Huh? This discussion is about GI issues, not weight gain/loss. I don't think I've ever heard anyone say that GI issues are about energy in vs energy out.

There is a moderately well supported theory that most "gluten intolerance" issues are actually intolerance of FODMAPs: certain fermentable sugars and short-chain starches found in a wide range of foods, most notably wheat. If you remove gluten from diet, you have likely also significantly reduced your FODMAP consumption. But gluten itself isn't a FODMAP, and I once baked an experimantal loaf of low-FODMAP bread using spelt flour and vital wheat gluten. (It wasn't very good.)