I am currently feeding my terrier on Arden Grange as he reacts badly to wheat. I think he could be doing better though and Arden Grange has a lot of maize in it.
The vet told us he is a few pounds overweight. He will be 6 this year and gets walked about 2 to 2.5 miles a day and we play games too. We wfh and are always together.
I have been reading how a lot of grain-free foods are full of legumes - peas,lentils, chickpeas... apparently they can cause cardiac issues 
I read on another forum that someone’s vet recommended sticking to the big manufacturers as the small boutique companies don’t use nutritional bets or feeding trials.
I would be okay with only rice and some potato though. I am struggling to find this however.
On a tight budget but would cut back on something else to buy DDog whatever he needs.
Tbh I am overwhelmed with it all and didn’t realise how many brands were on the market!