I'm 63 so I've worked at losing weight for the past five years but my problem has been putting it back on. Not all of it, but some of it, because my husband is a person who eats anything and everything ALL the time and never gains weight even though he has to take a high dose of thyroid medicine daily. I've just found Richard Bernstein MD who wrote "the Diabetic Diet" and I'm learning so much about having Metabolic Syndrome/INSULIN RESISTANCE. He is a Type 1 Diabetic since age 12 and he's 78 now. He has lectures on YouTube and I recommend him highly, because what he says about blood sugar and INSULIN RESISTANCE is so important to those of us over 40 and obese. I've learned that I'm obese because of the high SUGAR/STARCH diet and NOT because of high FAT.
He says age isn't the key factor but being in the best physical shape for any age and like Jack LaLanne, the Godfather of Fitness who lived to be 96 said "You can't push your body to hard because all it will do is get STRONGER no matter what age you are." I certainly know YOGA is helpful at our age now as being flexible is so important.