definitly keep it up, whatever u do dont get discouraged. if u want ease on the knees, try doing the bicycle or oliptical,just getting the heart rate up some weight training wouldnt hurt eather, just light weight, high reps, with weights u burn calories too, more than running as long as u keep it high reps and get your heart rate up. If u have a light lifting schedule and cardio u will loose weight alot faster. oh and dont cut out fats all together, u need them in order to get the results u want. their is a ratio for it, its something like .5 grams of fat per 10 pounds of bodyweight, 1.5 grams per 10 pounds of bodyweight for protien, and same for carbohydrates. Just remember complex carbs, whey protien, fruits, vegtables, penuts or cashews that are unsalted and good fats. also salt is the enemy, it makes your body retain water. low low salts. U will be where u want in no time.
p.s- look up THE ABS DIET. Its a great book talks about all the types of foods and what u need to watch out for. Helped me out alot