Fitness means being in good physical condition, being healthy, having more energy and better sleep patterns. A person who is fit is also able to carry out tasks more easily. Fitness may help prevent certain diseases such as high blood pressure, diabetes, stroke, cancer, and heart disease. You do not have to be an athlete to be fit. A brisk half-hour walk every day can help you reach a good level of fitness. Staying active and fit can also help you manage your weight and reduce the risk of obesity.
What is BMI? Body mass index (BMI) is a measure of body fat based on your weight in relation to your height, and applies to most adult men and women aged 20 and over. For children aged 2 and over, BMI percentile is the best assessment of body fat.
One of the most common questions we have received in our email inbox is "how much should I weigh?" In this article, we will explain 4 common methods to help you work this out.
To determine how much you should weigh (your ideal body weight) several factors should be considered, including age, muscle-fat ratio, height, sex, and bone density.
Some health professionals suggest that calculating your Body Mass Index (BMI) is the best way to decide whether your body weight is ideal. Others say that BMI is inaccurate as it does not account for muscle mass, and that waist-hip ratio is a better method.
It's worth remembering that one person's ideal body weight may be completely different to another's. If you compare yourself to family and friends you risk either aiming too high (if you are surrounded by obese or overweight people), or too low (if everyone around you works as a fashion model). Even comparing yourself with people outside your immediate surroundings may not work.
The levels of overweight and obesity in countries as the USA or UK, are much higher than in countries such as The Netherlands. So a Dutch person may aim for a lower ideal weight than an American if all he did was to compare himself to other people.
A recent study may have turned national guidelines on people’s ideal weight on its head. Researchers found that overweight people have a lower all-cause mortality risk compared to those of normal weight.
Method 1: Body mass index (BMI)
Your BMI is a measure of your weight in relation to your height. Health authorities worldwide mostly agree that:
People with a BMI of less than 18.5 are underweight.
A BMI of between 18.5 and 25 is ideal.
Somebody with a BMI between 25 and 30 is classed as overweight.
A person with a BMI over 30 is obese.
In some countries health authorities say the lower limit for BMI is 20, anything below it is underweight.
Calculate your BMI
To calculate your BMI use our BMI calculators or review our charts. We've given options for both metric and imperial measurements.
Weight and height guide chart
The following weight and height chart uses the National Institute of Health's body mass index tables to determine how much your healthy weight should be for your height.
What is the problem with BMI?
BMI is a very simple measurement which does not take into account the person's waist, chest or hip measurements. As an extreme example of this, an Olympic 100m sprint champion is likely to have a BMI higher than a couch potato of the same height. The couch potato may have a big belly, not much muscle and a lot of body fat on his hips, upper thighs, in his blood and on other parts of his body. While the athlete will have a smaller waist, much less body fat, and most likely enjoy better health. Using a pure BMI criteria, the couch potato may be considered healthier.
BMI does not take into account bone density (bone mass). A person with severe osteoporosis (very low bone density) may have a lower BMI than somebody else of the same height who is healthy, but the person with osteoporosis will have a larger waist, more body fat and weak bones.
Many experts criticize BMI as not generally useful in evaluation of health. It is at best a rough ballpark basic standard that may indicate population variations, but should not be used for individuals in health care.
Put simply: experts say that BMI underestimates the amount of body fat in overweight/obese people and overestimates it in lean or muscular people.
Other methods of finding your ideal weight
Should you not be satisfied with using BMI to work out how much you should weigh, there are other measurement options open to you.
Method 2: Waist-hip ratio (WHR)
A waist-hip measurement is the ratio of the circumference of your waist to that of your hips. You measure the smallest circumference of your waist, usually just above your belly button, and divide that total by the circumference of your hip at its widest part.
If a woman's waist is 28 inches and her hips are 36 inches, her WHR is 28 divided by 36 = 0.77. Below is a breakdown of WHR linked to risk of cardiovascular health problems.
Male WHR
Less than 0.9 - low risk of cardiovascular health problems
0.9 to 0.99 - moderate risk of cardiovascular health problems
1 or over - high risk of cardiovascular problems
Female WHR
Less than 0.8 - low risk of cardiovascular health problems
0.8 to 0.89 - moderate risk of cardiovascular health problems
0.9 or over - high risk of cardiovascular problems
The WHR of a person is commonly said to be a much better indicator of whether their body weight is ideal and what their risks of developing serious health conditions are, compared to BMI. Various studies have shown that people with apple-shaped bodies - who have larger WHRs - have higher health risks compared to people with pear-shaped bodies - who have lower WHRs. An apple-shaped person will have more fat accumulating on the waist, while a pear-shaped person has the fat accumulating on the hips.
A woman with a WHR of less than 0.8 is generally healthier and more fertile than females with higher WHRs. They are less likely to develop diabetes, most cancers, or cardiovascular disorders. Similarly, men with a WHR no more than 9 are generally healthier and more fertile than men with higher WHRs, and less likely to develop serious conditions or diseases.
Studies indicate that if WHR were to replace BMI as a predictor of heart attack worldwide, figures would include many more people.
What is the problem with WHR?
WHR does not accurately measure a person's total body fat percentage, or their muscle-to-fat ratio. However, it is a better predictor of ideal weight and health risks than BMI.
This information is from the MEDICAL NEWS TODAY NEWSLETTER.
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