I tend to stay away from most Safe Choice grains because of the high NSC, but I have heard good things about the SC Perform. Like SketchyHorse said, there really isn't that much of a difference in fat content compare to the SC Original, so you may be better off just adding a fat supplement/weight booster. I have fed Cool Calories in the past and really liked it, but to be honest the best thing that put weight on my hard keepers was good quality free choice hay. If you have Blue Seal grains or Sentinel grains in your area I HIGHLY recommend you try the Sentinel Performance LS. It is made for hard keepers, rescue horses, or high performance horses that need the extra calories. It's extremely palatable and is pressure cooked to optimize food breakdown and digestion. I have never had a horse turn their nose up to it and it has ZERO molasses so it can be safely fed to horses with Cushings, Insulin Resistance, Tye-Up, Ulcers, etc. Just a whole lot of fat & fiber with only 12% NSC compared to SC which is 28% NSC. Another thing you could try is rice bran, plain beet pulp, hay stretcher (be careful with NSC and molasses), or other fibrous/fat feeds. Also remember that if you're not feeding the recommended amount of grain that the bag suggests then you will need to supplement a vitamin/mineral ration balancer for him to get all the required nutrients that hay alone will not provide.