Grain free really is the way to go. One of our cats developed feline diabetes over the summer and I did extensive online research regarding what to feed him. Within 2 weeks of changing his diet to an all-wet/grain free diet, he was off his insulin and hasn't had a blood glucose reading over 110 since.
I realize it's more expensive, but then again so are diabetic testing strips, insulin, syringes, and trips to the vet. I would much rather have a healthy and active kitty because he eats a good diet than lose him early to something that could have been avoided.
Totally agree. Take it from someone who made this mistake of ignoring the signs until the damage was done. I used to dry feed exclusively. Both cats became overweight. I had been free feeding, so I started limiting their amount. One cat lost a little of the flab, the other kept getting bigger. They both also had dander issues. I tried going to really high-quality, grain-free dry food. It did help, but still not much. The really big one developed asthma, and the "thinner" one kept having her eye get watery/itchy, itchy ears, lots of hairballs (we thought), as well as scarfing and purging. At my wits end! Finally, I switched to all wet. Holy cow! Finally they started losing the flab, their coat became so soft and silky. Less stinky potty visits too (more yay for me than them

).
Unfortunately, after all those years of weight, the damage was done to the joints. The larger one can only jump down and up to very small heights. We had to build her a ramp just for the couch. The thinner one had better mobility, but still greatly diminished from what it should have been. We just lost her a few weeks ago b/c it turns out her hairballs was actually asthma as well...just showed differently than my other cat, and she hid it very well. Her lungs became too damaged, and she suddenly went into fatal distress. I will never know if the asthma issues they'd had was related to the foods I fed them, but I know being overweight made it worse, and she showed signs of allergy issues with the eye and scratchy ears while on the dry food.
And as this is the budget board, I will add that it's better to spend money on better food than vet bills later. Of COURSE, many many cats do fine their entire life on even cheap dry food. Reality is cat's aren't made to be on dry food -- but I also know reality is it's better that they have any food from a loving caregiver than none at all. If you can swing it, consider going with wet. I'm not trying to freak you out. But if your cat is already gaining weight on the dry, consider making a change now.
That being said, if you have to go with dry, go with a grain-free. Wellness is good, as is Evo. Best of luck to you and your furry friend.