To lose weight one needs to burn more calories than one consumes daily. Other than this, there are no short cuts, to loose weight. And note that weight loss does not always means fat loss, as weight consists of both lean body mass and body fat.

Estimation of the Nutrition needs of a 140 pound women

1) First calculate energy requirement (calories) by calculating her daily energy expenditure.
2) Then multiply bodyweight (in pounds) by 11: Here it is 140x11=1540 calories
3) Next, choose the correct exercise level and multiply the Calorie number determined above by the percentage associated with the exercise level. 20% for no exercise 25% for light exercise every day 30% for moderate exercise every day 35% for very intense exercise 3 or 4 days
a week.
4) In this example, 25% is used because we are assuming that the woman exercises moderately. Therefore, the physical activity energy expenditure would be: 1540 x 0.25 = 385 Calories.
5). Add this number to the original number to get total energy expenditure: 1540 + 385 = 1925 Calories.

The women's weight would remain intact, if her calorie intake is 1925 per day.
To start fat loss, adjust total energy expenditure by 0.9 to get a 10%
Calorie deficit. = 1925 x 0.9 = 1732. Thus 1732, Calories per day should be the women's daily intake for fat loss, in her case.

General Body Fat Percentage Categories From the American Council on Exercise

Classification Women (% fat) Men (% fat)
Essential Fat 10-12% 2-4%
Athletes 14-20% 6-13%
Fitness 21-24% 14-17%
Acceptable 25-31% 18-25%
Obese 32% plus 25% plus