Dieting Basic
Gather some quick essential knowledge of dieting before you start on your next diet plan. Learn what is Basal Metabolic Rate (BMR) and how to compute your BMR. Use BMR to derive your daily energy needs. Learn how to translate your weight loss target to calorie values. Know the different measurements use for food energy: calorie versus Calorie versus kilocalorie. And finally you will be able to determine the amount of food you have to eat per day to reach your target weight.
Basal Metabolic Rate (BMR)
BMR is the rate at which energy is used by an organism at complete rest. (cited from The American Heritage Dictionary) BMR is important to you because BMR gives the amount of energy you need to supply your body (from food intake) per day so as to maintain your current body weight. There is no quick and easy way to accurately measure your BMR. However, there are empirical formulae to estimate your BMR but these are good enough for our purpose.
Calculate BMR using Empirical Formulae
There are several empirical equations available to compute BMR. Among these equations, the Harris-Benedict equation is one of the most widely used and more accurate prediction equation. There are two equations; one for women and the other for men.
BMR (men) (kilocalorie/day) = 66.5 + (13.75 x weight in kg) + (5.003 x height in cm) - (6.775 x age)
BMR (women) (kilocalorie/day) = 655.1 + (9.563 x weight in kg) + (1.850 x height in cm) - (4.676 x age)
(A Biometric Study of Basal Metabolism in Man. JA Harris, FG Benedict - Washington, DC: Carnegie Institute, 1919)
Calculate Daily Energy Needs (DEN) from BMR
The BMR formula only gives your daily energy needs if you are at complete rest. To compute your daily lifestyle energy needs, you need to determine your activity level and multiply your BMR by the corresponding activity factor.
DEN (kilocalorie/day) = BMR x Factor
| Activity Level | Activity Description | Factor |
| Sedentary | Little or no exercise, desk job | 1.2 |
| Lightly Active | Light exercise/sports 1-3 days/week | 1.375 |
| Moderately Active | Moderate exercise/sports 3-5 days/week | 1.55 |
| Very Active | Hard exercise/sports 6-7 days/week | 1.725 |
| Extremely Active | Hard exercise/sports 7 days/week and physical job | 1.9 |
(McArdle, et. al. 1996)
Calorie versus calorie versus kilocalorie
These are the different measurement units for energy value. They may seem confusing at first. But don't worry, it actually quite easy to understand.
1 kilocalorie = 1 Calorie = 1000 calorie
Calculate Daily Food Intake to Reach Ideal Weight
The final step is to compute the amount of food you should eat to reach your targeted weight. To compute this value, you need to have the following information
- DEN (Daily Energy Needs), from above section
- Intended Weight to Lose (in kg)
- Intended Time to achieve Weight Loss (in days)
Daily Food Intake (kilocalorie/day) = DEN - [9000 x (Intended Weight Loss) / (Intended Time)]
(assume all weight loss is from fats. 1g of fats give 9 kilocalorie)
A Word of Caution
It is always advisable to consult your doctor before you embarked on any diet plan. Embarking on a very low calorie diet is definitely not suitable for everyone and you should seek professional advice first. Last but not least, you should set a reasonable weight loss target within a realistic time frame.
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