Waist Circumference and health risk
Waist Circumference is the circumference measurement taken at the small of the back. It is one of the metrics our director encourages all clients to track over a lifetime.
A larger waist circumference can mean more "deep" (visceral) fat. Visceral fat is an unhealthy type of fat that wraps around internal organs and can lead to additional health risks. Generally a lower waist circumference is better.
Men with a waist circumference higher than 102cm are 2.25 x more likely to suffer from coronary heart disease than men with a waist circumference less than 84cm. Women with a waist circumference higher than 88cm are 2.75 x more likely to suffer from coronary heart disease than women with a waist circumference less than 71cm. The reference for this can be found here
How to improve Waist Circumference
What you eat/drink will have the largest direct affect on your waist circumference, from what you can control of course (e.g. you can't control your genetics, age, sex).
For some, exercise can assist in lower waist circumference. Doing sit ups or exercises that strengthen your stomach muscles will likely have no effect on your waist circumference. Whole body, large movements that burn a lot of energy/calories are most likely assist in decreasing your waist circumference than targeting the stomach alone.
As you can't specifically target your waist for weight loss, you are best to read the following articles if you want to decrease your waist:
BMI, waist circumference and diabetes risk
Obese men (BMI > 30) with a large waist >102cm were 22 times more likely to develop diabetes than men with a low-normal BMI (18.5-22.4) and a smaller waist (less than 94cm).
Obese women (BMI >30) with a large waist (>88cm) were nearly 32 times as likely to get diabetes than women of low-normal BMI (18.5-22.4) and a smaller waist (less 78cm).
The reference for the study above can be found here