I found this interesting for base metabolic rate.

Q: How many calories should I eat to lose weight?

I was wondering what my body burns just to exist before any foods for energy need to be consumed etc.

So this is how you do the formula
I personally use 1,305 calories a day just to breath and function...and would need to eat approx 2000 a day to maintain weight based on a moderately active life style.

To lose 1 pound of fat i’d Need to cut 3,500 calories from input and add a 10 - 20 min walk in 3 times a week to shed more that a pound a week.
of winter storage on at this time of year, I have to admit i’m A bit of an obbsessive if I put on even a couple of pounds as I hate feeling squishy, I am one of those on the scales every day - checking and trying to be the size uk 8 - 10 always.

A: Calculating the number of calories you need to lose weight is a relatively simple, three-step process. (And it will help you figure out how to lose 10 pounds safely.) The Harris-Benedict equation is the most widely used method of calculating your calorie needs (and thus how many calories you need for weight loss). Here is the Harris-Benedict equation to find out how many calories a woman should eat a day:

BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)

You just need to plug in your age, height, and weight. The number you get is the total number of calories you need each day to exist (also known as your basal metabolic rate, BMR). For example, a 50-year-woman who is 5' 7" and weighs 160 lbs has a basal metabolic rate of 1441 calories.