Body mass index(BMI) is a calculation that takes a persons weight and height into account to measure body size.
In adults, obesity is defined as having a BMI of 30.0 or more.
Causes of obesity.
Genetics which can affect how your body processes food into energy and how fat is stored.
Growing older which can lead to less muscle build up and slower metabolic rate, making it easier to gain weight.
Not sleeping enough which can lead to hormonal changes that make you feel hungrier making it easier to gain weight.
Pregnancy weight gained during pregnancy may be difficult to lose and may lead to obesity.

Diagnosis.
Based on a physical exam and patients history.
BMI doesn’t directly measure body fat but is useful tool to access the health risks associated with obesity.
BMI = body weight(kg) ÷ height(m)
BMI;
Less than 18.5 is underweight.
18.5- 24.5 is normal weight.
25.0-29.9 is underweight.
30.0-34.9 is obese class 1.
35.0-39.9 is obese class 2.
40.0 or higher is obese class 3.
Treatment and prevention.
Changing your lifestyle.
It can be difficult but with a plan, effort, regular support and patience you may be able to lose weight and improve health.

Weight management programs.
In a weight management programs trained specialists will design a broad plan just for you and help you carry out your plans. Plans include lower calorie diet, increased physical activity etc.
Weight loss medicines.
When healthy eating and physical activity habits are not enough your doctor may prescribe medicines to treat obesity.
Weight loss devices.
Your doctor may consider weight loss devices like gastric balloon system, gastric emptying system etc.
Bariatric surgery.
Includes several types of operations that help you lose weight by making changes to your digestive system.
Intermittent fasting.
Another way of reducing food intake that is gaining attention as a strategy for weight loss and health benefits.