When my brother had this problem, he had to retrain the cats to a new
feeding schedule:  the overweight cat got fed in the kitchen, the other got
fed in the bathroom.  No more free feed.  If the female seem to be losing
weight, you might try giving her a higher calorie food, like kitten chow,
or, unless you're dead set against canned food for whatever reason, a bit of
canned mixed in with her kibble, or as a 'treat' later if she likes it.
That's what I did when my Smokey lost weight after most of her teeth were
pulled.

I think you will find that the only way to monitor the situation is to
eliminate free feeding.  Canned food would provide a healthier diet and
would also be easier to monitor.  I use Wellness canned and Felidae canned.
Each cat receives 1/3 can of food twice a day (I use the small 5.5 or 6 oz.
cans because I only have two cats).  I schedule their feedings for 12 hours
apart, or as close to that as possible.  Approximately every 3 days, I put
out 2/3 cup of Wellness dry food as a "treat" and just leave it until it is
gone (1/3 cup in each of two separate bowls, although either cat will eat
out of each bowl).  Their weight has remained stable on this diet, with very
little fluctuation -- and they even have far fewer furballs than they did
when they were fed a dry food diet.  One cat weighs a little more than 8
lbs., and the other weighs slightly more than 9 lbs.  One cat had gained a
pound over the last year before I started this diet.  She lost that weight
and is now maintaining her optimum weight.  Depending on how much weight
your male cat needs to lose, you might need to use different quantities for
awhile.

MaryL

The *only* way to make sure they eat their recommended daily amount is to
feed them *separately* and in measured portions.

.Free-feeding may work for individual cats that can self-regulate their
daily intake of calories to match their DER, but if your cat could
self-regulate his caloric intake you wouldn't have this problem, would you?
;)  Free-feeding rarely works for weight loss or for maintenance of reduced
weight even with the best  weight loss diets.  Any weight-loss program is
doomed to fail?ure before it even begins if you can't or won't feed your
overweight cat(s) separately and keep them  from eating the other cats'
food.

Separate feedings may seem inconvenient, but I can assure you that its a
helluva lot more convenient than feeding your cat through a feeding tube or
checking his blood sugar and giving insulin dosages twice a day.  Obese cats
are at higher risk for hepatic lipidosis and diabetes.

If you're interested in a tried and true weight loss program for your cat,
let me know.

Phil

phil@maxshouse.org