As you age, your metabolism decreases leading to weight gain. Since you have a sitting job and being a woman, you are prone to put on weight near the stomach and hip
areas as a woman is genetically designed to have a pear-shaped body. I advise you to join a gym and alternate between weight training and cardio to help build muscle mass and burn fat. Along with this, you need to eat a balanced diet
with lots of fibre, greens, veggies, nuts, salads, curd, etc.
Here is a diet plan for you:
have a healthy breakfast to keep you going for the morning. Include items like oats porridge/ oats upma/ idli/ dosa.
Between breakfast and lunch, have a fruit and a handful of nuts.
In lunch, eat a portion of salad, a jowar/ragi chapatti with veggies, dal and a glass of buttermilk (chhaas).
Keep your dinner light. You can have soup, salad, veggies/grilled chicken or fish. Avoid eating rotis or rice at night.
Along with this, drink two-three cups of green tea every day and sleep well.