I am 70 yrs old and I have been doing the Mediterranean diet for 5 yrs now and I love it. When we get older our metabolism gets slower and this is why it is difficult for us to lose weight. I was close to 190 pounds when I started this diet having high cholesterol, high triglycerides and high LDL which is bad for the heart. Today I have kept myself around 165 pounds because for me this is my ideal weight. My lipid levels are normal. This diet is based on fruits, vegetables, pork tenderloin, fish and chicken, grains, nuts (almonds , pistachios and very few walnuts)
I eat more chicken and fish (salmon, halibut, cod). I don’t eat anything that has more than 5% Saturated fat but if I find any foods with 0% saturated fat that will be my choice. I absolutely don’t eat cakes, cookies, butter).
There are Mediterranean diet recipes that you could check them out. Easy to prepare.
A Mayo Clinic physician once told me: keep your plate 3/4 full of vegetables, grains & salad, 1/4 chicken, fish, pork or lean meat.
I drink lot of water and even though I don’t go to the gym I try to walk at least 30 minutes each day.
I hope this helps but remember before starting any diet consult your physician.
By the way this physician in Mayo never recommended me to follow the Keto diet ( too high in saturated fat).
Stay safe and healthy.

I think it's all about the calories we take into our bodies. I've seen my husband just have the weight just melt away because he counted every calorie...good luck !