How big is too big?

I have a 3 and a half year old, Old English Mastiff
neutered female. Her father was 220 pounds, her mother was
180 pounds. I took her to the Vet Friday and she
weighed in at 136.6lbs. I was told by the Vet that
she was over weight and she asked how much Rayn is
fed. Rayn is fed 2 cups of dry large breed dog food
and 1/3 cup of canned food mixed together twice
daily and this was originally cut down at the beginning of March from 36oz of dry and half a can of soft mixed due to her weight, but she hasn't lost any weight, maybe half a pound. The vet said it doesn't matter how much
her parents weighed and that Rayn had "fat pockets"
on her hips. So, she has been cut down to 1 3/4 cups
of dry mixed with 1/4 cup of canned 2 times a day, which
she gobbles up in TWO bites. Is this enough food for her?
Her mother deveoloped mastitis (?) with 13 puppies in her litter and all had to be bottle fed and Rayn was the smallest of the litter and a little on the malnourished side
when we got her. She doesn't get table scraps at all, but does get raw carrots, apples, ice and large beef marrow bones from the butcher regularly as "treats". I feel like she thinks she is being "punished" because she sits and looks for more when she is done eating her 2 "meals" a day, that in my opinion, might satisfy a medium 50-75 lb. dog. I also worry about her weight and hip displaysia even though this has not been a factor in her Pedigree histroy.
Any help is gratefully appreciated and thanks in advance.

Hello,
Our mastiff weighs 185 at 10 months old. He eats raw food and eats about 8 pounds a day (about 16 cups of dry food)You can still see all of his ribs.  I do know that mastiffs in general (the ones in the show ring) none of the females reach over 200.  Your girl is on the big size, although it depends on her lines.  She should have a mild tuck up and muscles too.  Hip dysplasia is definilty something to worry about, although if you start slowly walking her up and down hills that should be good for her.  And as for her food, try adding things that have high fiber such as green beans or such. BUT make sure to grind them up, if given whole, the dogs can't digest them (from what i am told, they can't break down through the cell walls of the veggies) So they must be pulverized!  Good luck!

Hi welcome!
Is it possible for you to post some more pics of your dog?
I have a 7 yr old male that is 160 pds, and eats between 4-5 cups plus additives.  My 2 yr old male is 206 pds and is now eating 10 cups plus additives.
When you stand over her, can you see her ribs? Does she taper from her ribs to her back thigh?  I can't really tell from the picture.
Every dog will be different.  Some are smaller boned and some are very large.  My 2 year old is larger than both his parents.  It will also depend on the exercise that she's getting.
There is a breeder near where I live in Canada that has a 275 pd stud dog.  His females also go between 210 -240.  Now his dogs are very true to the original breed and he calls them 'typey'  He gets his breeding stock from Europe.

Here is a mastiff weight chart, but remember, it's just guideline.

Weight Chart for Mastiffs

     Male / Female (in lbs)
8 wks  29 /24
9 wks  33 /29
10 wks 36 /32
11 wks 40 /36
3 months 45 /39
4 months 60 /50
5 months 80 /65
6 months 100 /80
7 months 125 /90
8 months 140 /100
9 months 155 /110
10 months 165 /112
11 months 170 /115
12 months 175 /120
13 months 180 /122
14 months 185 /125
15 months 188 /125
16 months 189 /125
17 months 190 /127
18 months 192 /127
2 years 205 /135
30 months 210 /140
3 years 215 - 225  /155 - 180
4 years 220 - 230  /160 - 190
5 years 220 - 235  /170 - 200