There are lots of formulas for weight loss. I use The Harris-Benedict Principle when calculating Basal Metabolic Bate (BMR). Here's the formula.
Men
66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.76 x age in years)
Women
655 + (4.35 x weight in pounds) + (4.7 x height is inches)
Then multiply in a factor for daily activity
Little to no daily Exercise BMR x 1.2
Light Exercise (1-3 days per week) BMR x 1.375
Moderate Exercise (3-5 days per week) BMR x 1.55
Heavy Exercise (6-7 days per week) BMR x 1.725
Very Heavy Exercise (Twice a day, extra heavy workouts) BMR X 1.9
A Male Example
35 years old, 5' 10" 180 pounds
66 + 6.23 x 180 (pounds)= 1121.4
+ 12.7 x 70 (inches)= 889
- 4.7 x 35 (years)= 164.5
BMR=1911.9
X Moderate Activity (3-5 Days per week)
1911.9 x 1.55=
2963.45 Calories per day
To maintain current weight
If you want to lose weight you must have a negative Kcal balance or burn more Kcal each day than you eat. Many trainers encourage people to reduce your Kcal intake by 500 a day. I want my people to eat 250 fewer and burn 250 more to achieve the 500 total calorie negative balance.
The important factor for you to know is what percent of each macro nutrient do I need daily. What is my body's need in terms of fats, protein and carbohydrates?
What should I eat?