Personal trainers recommend ab workouts for those over 40 that incorporate strength training 3 times a week combined with a high-protein, low-calorie diet. They also suggest high-intensity interval training 2 times a week and weight training 3 times a week to build muscle mass and boost metabolism. Core exercises using body weight or extra weight are most effective for toning the abdominal region. Eating breakfast daily without skipping and taking long walks before lunch can complement ab workouts after 40.