I have followed the blood type diet for A's simply because a good (and very food smart)friend told me she liked it. I was also encouraging my DD who had some digestive challenges.
Yes, you can low carb. It's actually a very nice low fat way to go. I ate lots of salads and fish and chicken.
Over time I've become far less restrictive. I've added back some dairy with no problem. I still watch tomatoes and potatoes which actually do bother me.
Especially for A's, I think it's a wonderful start for learning the importance of that with which we fuel our bodies. I'm not in with the science but ... there's no harm in using the blood type diets with a little added wisdom and moderation.
Eat good food. Move yourself. Lift something.
You'll be surprised how much you don't miss grain.