Is bmi 19 ok?

It is normal for your body to store energy as fat. However, too much or too little body fat can increase your risk of illness and disease, depending on where your body stores it.

The amount of fat your body has stored can be accurately measured with a dual-energy absorptiometry (or DXA) machine. This is known as having a DXA scan. A much cheaper alternative is to estimate your total amount of body fat by calculating your body mass index (BMI).

BMI is a useful indicator of health at the population level. However, the distribution of fat on your body is more important that the amount, when assessing your disease risk. For this reason, your waist circumference is thought to be a better predictor of health risk than your BMI.

Increased abdominal obesity is related to a higher risk of cardiovascular disease, type 2 diabetes and cancer. Abdominal obesity is measured using waist circumference.

Body mass index (BMI) is an approximate measure of your best weight for health. It is calculated by dividing your weight in kilograms by your height in metres squared (m2).

BMI is intended for adults only, as children and adolescents are constantly growing. This makes it difficult to have set values for BMI cut-offs for young people. However, in adults who have stopped growing, an increase in BMI is usually caused by an increase in body fat.

You can use the body mass index (BMI) calculator for adults to calculate your BMI, provided you know your:

Your BMI will classify you as ‘underweight’, ‘healthy weight’, ‘overweight’ or ‘obese’, as defined by the World Health Organization. If your BMI is:

For older Australians over the age of 70 years, general health status may be more important than being mildly overweight. Some researchers have suggested that a BMI range of 22–26 kg/m2 is desirable for older Australians.

At the population level, BMI is used to indicate level of risk for morbidity (disease risk) and mortality (death rates).

Differences in BMI between individual adults of the same age and sex are usually due to body fat, however there are many exceptions to this rule, which is why a BMI figure may not always be accurate. BMI calculations will overestimate the amount of body fat for:

BMI calculations will underestimate the amount of body fat for:

BMI is also not an accurate indicator for people with:

Generally speaking, the more body fat you’re carrying, the higher your health risk. However, BMI cannot differentiate between body fat and muscle mass. This means there are some exceptions to the BMI guidelines:

BMI calculations used for adults are not a suitable measure of weight for children or adolescents. BMI calculations for children and adolescents are interpreted differently from an adult’s and take into account the age and sex of the child or adolescent. The current BMI charts for children have been developed by the US Centres for Disease Control and Prevention. They are useful for the assessment of overweight and obesity in children aged over two years.

To calculate a child's BMI, you can use the body mass index calculator for children and teenagers.

However, BMI charts should be used only as a guide to indicate when to make small lifestyle changes, and when to seek further guidance from a doctor or a dietitian.

The link between being overweight or obese and the chance you will become ill is not definite. Research is ongoing. Statistically, there is a greater chance of developing various diseases if you are overweight. For example, the risk of death rises by 20 to 30 per cent as BMI rises from 25 to 27kg/m2. As BMI rises above 27 kg/m2, the risk of death rises more steeply (by 60 per cent).

If you are overweight (with a BMI over 25kg/m2) and physically inactive, you may develop:

If you are underweight (BMI less than 18.5kg/m2), you may be malnourished and develop:

A person’s waist circumference is a better predictor of health risk than BMI. When identifying health risk in adults, it is recommended that you combine your BMI classification with your waist circumference as a measurement of disease risk. Having fat around the abdomen or a ‘pot belly’, regardless of your body size, means you are more likely to develop certain obesity-related health conditions. Fat predominantly deposited around the hips and buttocks doesn’t appear to have the same health risk. Men, in particular, often deposit weight in the waist region and therefore have an increased risk of obesity-related disease. Studies have shown that the distribution of body fat is linked to an increased prevalence of diabetes, hypertension, high cholesterol and cardiovascular disease. Generally, the associations between health risks and body fat distribution are:

Waist circumference can be used to indicate health risk for chronic diseases. For men:

For women:

How fat is too fat? A large new government-funded study found that being even a bit overweight can increase your risk of death from heart disease, stroke or cancer. The findings counter some data that have suggested that carrying a few extra pounds can be protective of health. So what should your ideal weight be?

After analyzing data on 1.46 million mostly white, non-Hispanic adults who participated in 19 long-term studies — each designed to follow participants for between 5 to 28 years — researchers determined that, overall, a BMI (or body mass index, a ratio of height and weight that determines overweight and obesity) between 20.0 and 24.9 was associated with the lowest risk of death in healthy non-smoking adults. (More on Time.com: The ‘Other’ Salt: 5 Foods Rich in Potassium)

Current guidelines from the Centers for Disease Control and Prevention, and the World Health Organization, define a normal BMI range as 18.5 to 24.9. Overweight is defined as 25 or higher; obesity is 30 or higher; and severe obesity is 35 and up.

The National Institutes of Health (NIH), which funded the study, reports:

The patterns of risk persisted, even after researchers accounted for differences in alcohol consumption, physical activity and education. The increased risk of death for a BMI of 25 was also seen in all age groups, the NIH reports, but it was more prominent in people who became overweight or obese before age 50. (More on Time.com: Fitness Tech: 10 Cool Ways to Get in Shape)

What about those at the low end of normal BMI? A healthy BMI ranges as low as 18.5, but longevity was associated with a minimum BMI of 20 in this study. “For women in the BMI category of 15 to 18.5 we observed the increased risk of death was 47%, and for women in the BMI category of 18.5 to 20 the increased risk of death was 14% compared to those in the BMI range of 22.5 to 24.9 (our reference group),” said the study’s lead researcher, Dr. Amy Berrington de Gonzalez of the National Cancer Institute. “However these risks decreased with longer follow-up suggesting they might at least partly be due to weight loss from pre-existing conditions rather than causal.”

The researchers excluded from the study people with heart disease or cancer at the start of the study, and those who smoked, since these factors influence risk of death. (More on Time.com: Photos: From Farm to Fork)

Studies are underway to determine the relationship between BMI and risk of death in other ethnic groups.

To calculate your own BMI, check out the NIH’s dedicated website.

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