Obesity is a substantial public health crisis worldwide, with the prevalence increasing rapidly in numerous countries. A report from the National Center for Health Statistics stated that in US individuals aged 20 years or older, the prevalence of obesity rose steadily from 19.4% in 1997 to 31.4% for the period January-September 2017.

Obesity is a leading cause for a number of disorders, including Diabetes , Hypertension, Strokes , Cardiovascular disease, Osteoarthritis, and many other conditions.

How obesity is measured?

Obesity represents a state of excess storage of fat in the body. Doctors measure obesity through a number of ways, including Body Mass Index BMI, Abdominal Girth , and Body Fat Percentage.

The following table shows normal and abnormal values( M = Male , F = Female):

	Underweight	Normal	Overweight	Obese	Morbidly Obese
Body Mass Index	<= 18.5	18.6-25	25.1-29.9	30-34.9	> 35
Body Fat Percentage		< 21% M < 31% F	21%-25% M 31%-33% F	> 25% M > 33% F
Abdominal Girth		< 100 cm M < 90 cm F	> 100 cm M > 90 cm F

How to Control Body Weight?

Your body weight is a result of a balance of your calories input and output. You obtain calories from food.

Input is what you eat. Output is what you spend in activity and body functions.

If the input is equal to the output, then you maintain your weight. But if input is more than output you gain weight. To lose weight your input should be less than your output. That means a decrease in amount of food calories and an increase in physical activity.

How To calculate your input and output calories?

To calculate input and output calories you need to know a number of things:

1. Your basal metabolic rate(BMR) : this is the amount of output spend by your body at rest for your biological functions like respiration, blood pumping, brain thinking, etc. BMR is different according gender and it decreases with age.The calculator below will do it for you.
2. Calories you take in meals: you can nowadays get the caloric values of food from the web easily. The fat secret website provides such values for almost every food, They have a mobile application too.
3. Level of your physical activity : output increased with increasing activity. The calculator below will do it for you..
4. Your weight and height.