Greetings. May i know your age?
To know your ideal weight, follow this :
If you do not have a measure tape , a rule of thumb to determine your frame size is to wrap your thumb and middle finger around your wrist on the opposite hand.
If you are of Small Frame your fingers overlap.
If you are of Medium Frame your fingers barely touch.
If you are of Large Frame your fingers don't touch.
Next based on your Height 5 feet 8" and body weight 198lbs,
Your Ideal weight range is 154 - 169.4 lbs (70 - 77 kg) & as of now you are
overweight by 28.6 lbs (13 kg).
For more precision, specialists recommend using a combination of
Body Mass Index (BMI), Body Fat and Lean Body Mass to figure an individual’s ideal healthy weight.
& finally before starting any diet to lose weight, be sure to consult and discuss with your doctor.
Hope it helped You.