M.P.
I'm guessing you've gradually gained weight over the last few years. That's normal. But if you haven't had a physical exam in last couple of years it's wise to do that.
The way to lose weight at 40 is the same as when you were 20 or 30. It's just harder to do. Eat less and exercise more. I'm 70. Over the years I went from 125 to 165. I've gained and lost several times. The same 20 lbs just by eating less. Then I gained 20 more lbs. 10 years ago and it was more difficult to lose it.
Three months ago I decided to get rid of that last 20 lbs. I'd gained on top of the first 20 lbs. and I lost them. Only this time I had to think every day, several times a day to not eat anything extra. Gone are the days of just being able to be aware without much conscious thought to eat less. Eating more was now an entrenched habit which required daily reminders to eat less. I'm working towards losing the next 20 lbs. And hoping to make eating less a habit once more.
I use luncheon sized plates and rarely have seconds. I allow myself 2 small snacks per day. I still eat sweets. I don't deprive myself of anything. I just consciously eat less.