At almost any major decade in life, our metabolism takes a major hit. Whether that is 20, 30, 40 or 50.
Weight loss can still be achieved at any age, but you have to increase your metabolism. Adding some weight training and resistance training to your regimen will go a long way toward helping increase your metabolism.
A few minutes of squats burns more calories than jogging or walking 6 miles. And squats will build muscle which will increase your metabolism. Eating small frequent meals throughout the day will increase your metabolism.
Similar to the issue that most women face, being over 50 years of age requires more work to lose weight. Reread the section on Women and Weight Loss
and read it as if it were speaking to you as a 50 year old.
Try to get into a "young" frame of mind. Don't always avoid activities or outings because "I'm too old for that." Make sure your physician has cleared the activity, then go do it. Horseback riding, golfing, basketball, fishing, biking, weight lifting, body building, volleyball, softball, and soccer are all activities that you can enjoy at any age. Get into a young mindset and get active.