my tollie has gained too much too fast help!

Actually, dogs metabolize fat differently than humans do, due to the completely different structure of their digestive tract. You have the right idea, but low fat doesn't help anybody (I'm of the rather strong opinion that it harms humans, as well. Our BRAINS operate on fats!!!). Try feeding the same food, but less of it (just cut back to one cup a day, and see how she does). If she's too hungry, add your own healthy fillers, like frozen green beans or raw carrots. Adding fish oil to the diet (essential fatty acids) can also assist in weight loss.

My Dachshund lost ten pounds on a reduced portion of a normal-calorie diet, with a good dose of fish oil added, daily. It works!!!

You dont allways have to change food to get weight off,just feed less of it.If they are still hungry you can add some veggies to bulk it up a little.Mine like green beans!

I don't love the diet lite foods they really are all about malnutrition if you are truly reading the content. Dogs lose weight by eating low fat protein not by eating fillers for diet.

Completely 100% agree with you there [8|] I've had overweight dogs in the past who i've managed to downsize by feeding less of their normal diet or switching to a different one.

Whats the k/cals per cup of prarie? How much off lead exercise does your dog get daily? A dog of yours size and massive energy levels should be getting at the very least 2 full hours of off lead exercise per day,everyday,preferably more!

A raw diet is a good way to go for not only health reasons,but for getting excess flab off of a dog. Is your dog used to raw? Did you perhaps introduce a full on raw meal too quickly?
Sorry,i've got loads of questions and i've been of no help at all [&o]

If you want to go raw,start off slowly,by perhaps introducing a chicken wing and reducing is kibble appropriately,then swap one meal of kibble for lightly cooked meat and so on until you've fully transfered over.Maybe your dog has a sensitive tum and needs to change foods slowly??

If you dont want to go full on raw you could look into kibbles with lesser fat and k/cals,and substitute one meal with raw or cooked. Adding veggies to their kibble is a good way to make them feel full whilst giving them less food(kibble).

If you are noticing sudden weight gain in an active dog and the weight doesn't come off with decreased portions, try checking the thyroid.

My thought exactly--have the thyroid checked.  Our first golden had low thyroid and he had all the classic symptons--hair loss, heair going thin, sudden weight gain, lack of energy, change in temperament. 
 
Now our old golden ws diagnosed about 1 1/2 years ago at age 10 and he had absolutely NO SYMPTOMS and his was lower than Scooters had been.  Some does have all the symptoms, some have none and some have one or two.  So to be on the safe side, get his thyroid checked.