Will I lose weight by doing 6 Laps on track at gym with brisk walk. Can’t jog for while due to knee. Apple Watch shows 40 min on exercise ring?

Keep moving. Weight loss varies by several factors including what one eats, amount of exercise, and the metabolism of the individual. Please focus on staying healthy more than the number on the scale. Keep moving w/walking as long as doc is ok w/that because of your knee. Ask doc about a low carb higher good fat diet. It can bring weight down. Body burns fat more than sugar this way. Peace & good health.