I usually add a little extra yeast (i.e. 1Tbsp vs 2 tsp), but the other thing that can be hampering your loaves is not enough gluten. If the dough doesn't stretch to contain the bubbles of air, and instead lets them escape, you get a heavier loaf. Gluten is developed by kneading and using an appropriate flour that can develop good gluten. If your flour doesn't develop enough gluten you can knead it longer, add gluten, or mix it with another flour that does develop good gluten, or some combination of those.
What does your dough look like if you do the windowpane test?
http://www.thekitchn.com/bakers-tech...to-do-th-70784
When I make Rye bread for DH, I mix it with a red spring wheat or even the white wheat I have here, because rye doesn't develop much gluten at all. I tried with Kamut, but the Kamut flavor wasn't very nice with the Rye.
Most of my loaves (unless done in the bread maker) are sourdough loaves which tend toward a heavy loaf anyway, which is why I had to learn some of the ways to mitigate it.
