I weigh 17 stone and am 5 ft 11 male. if i eat 500 calories per day for 3 months will i lose any weight?

Too extreme: Your body mass index is 45 = very obese. You may need professional help to create a sustainable diet/exercise plan. Walking + cycling are good; so is weightlifting to burn calories faster. But 500 cal is a starvation diet - not sustainable! slow and steady wins the race. Have to cut out sweets, sugar, sugary beverages, reduce starches + emphasize fruit, veg, whole grains, lean meat, low fat dairy.