Human Body Weight

Many people wish to know the answer to this question: how much should I weigh? However, there is no single ideal weight for all individuals.

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth.

Everybody is different, and various factors play a role in determining each person’s ideal weight. These factors can be biological, such as age, height, and natal sex, but mental factors can be just as important.

An individual may define their ideal weight as the one with which they feel the most comfortable.

However, maintaining a moderate weight can reduce a person’s risk of developing a number of health conditions, including:

However, not everyone with excess weight will develop health issues. However, researchers believe that while this extra weight might not currently affect health, difficulties in managing weight could lead to problems in the future.

Read on to discover the different ways of working out a person’s ideal weight.

Body mass index (BMI)

A person’s BMI is a common tool that measures a person’s weight in relation to their height. A BMI calculation provides a single number, which falls into the following categories: Trusted Source:

  • A BMI of less than 18.5 means a person is underweight.
  • A BMI of between 18.5 and 24.9 is ideal.
  • A BMI of between 25 and 29.9 is overweight.
  • A BMI of over 30 indicates obesity.

BMI based on age

Age is not a factor in BMI for adults, but it is for children. This is because they are growing. The Centers for Disease Control and Prevention (CDC) use both age and natal sex in their BMI calculations for people between the ages of 2 and 19 years.

To calculate a child’s BMI, a person can use the CDC’s calculator for children and teenagers.

The CDC’s BMI charts for children use percentiles that compare measurements with boys’ and girls’ trusted sources of the same age and gender.

What is the problem with BMI?

BMI is a very simple measurement. While it takes height into consideration, it does not account for factors such as:

  • waist or hip measurements
  • the proportion or distribution of fat
  • the proportion of muscle mass

These factors can affect health. For example, high-performance athletes tend to be very fit and have little body fat. They can have a high BMI because they have more muscle mass, but this does not mean they weigh too much for their height.

Another limitation of BMI is that it does not distinguish between people of different ethnicities. Studies have shown that at the same BMI, non-Hispanic whites, non-Hispanic blacks, and Mexican Americans may have significantly different levels of body fat.

This inaccuracy may lead to a misdiagnosis or an incorrect assessment of risk factors between individuals.

BMI can offer a rough idea of whether or not a person is at a moderate weight, and it is useful for measuring trends in population studies.

However, it should not be the only measure for an individual to assess whether their weight is ideal.

Waist-to-hip ratio (WHR)

A person’s WHR compares their waist size with that of their hips. A high WHR indicates that an individual has higher levels of visceral fat, the fat in the abdominal cavity that surrounds several major organs.

Research has shown that people with a high WHR are more likely to develop CVD and diabetes.

The higher the waist measurement in proportion to the hips, the greater this risk. For this reason, the WHR is a useful tool for calculating whether a person has a moderate weight and size.

Measuring WHR

To calculate their WHR, a person should measure around their waist at the narrowest part, usually just above the belly button. They can then divide this measurement by the width of their hip at its widest part.

For example, if a person’s waist is 28 inches, and their hips are 36 inches, they will divide 28 by 36, giving a WHR of 0.77.

What does it mean?

According to an older report from 2008, “from the World Health Organization (WHO), optimal WHR differs between sex at birth and ethnicities.

Having a high WHR can put people at a higher risk of CVD and other conditions with links to increased weight, such as type 2 diabetes.

The following are average values for WHRs and their associations with health risks.

Studies have linked having a high WHR with an increased risk of developing myocardial infarctions, commonly known as heart attacks.

However, as with BMI, the WHR does have limitations. For example, this measure does not measure a person’s total body fat percentage or their muscle-to-fat ratio accurately.

To discover more evidence-based information and resources for obesity & weight management, visit our dedicated hub.

Waist-to-height ratio

The waist-to-height ratio (WtHR) is another tool that might predict the risk of heart disease, diabetes, and overall mortality more effectively than BMI.

Measuring WtHR

To calculate WtHR, a person should divide their waist size by their height. If the result is 0.5 or less, they are likely to have a moderate weight.

A 2014 study concluded that a WtHR of 0.52 or above significantly increases a person’s risk of developing heart complications. Measurements that take waist size into account can be suitable indicators of an individual’s health risks. This is because the fat that collects around the middle of the torso can be harmful to the heart, kidneys, and liver.

Body fat percentage

Body fat percentage is the weight of a person’s fat divided by their total weight. This measurement includes both a person’s essential and stored fat.

An individual needs essential fat to survive — it is critical for the development of the brain, bone marrow, nerves, and membranes.

Storage fat is the fatty tissue that protects the internal organs in the chest and abdomen, and the body can use it if necessary for energy.

Recommendations

Apart from the approximate guidelines for males and females, the ideal total fat percentage can depend on a person’s body type or activity level.

A high proportion of body fat can indicate a greater risk of:

Calculating body fat percentage may be a suitable way to measure a person’s fitness level because it reflects their body composition, unlike DMI, WHR, and WtHR.

How to measure body fat

The most common way of measuring body fat percentage is to use a skinfold measurement, which uses special calipers to pinch the skin.

A health professional will measure tissue on the thigh, abdomen, and chest for males or upper arm for females.

Other measures include

  • hydrostatic body fat measuring, or “underwater weighing”
  • air densitometry, which measures air displacement
  • dual-energy X-ray absorptiometry
  • bioelectrical impedance analysis

While none of these can give an accurate reading, the estimates are close enough to offer a reasonable assessment.

Takeaway

BMI, WHR, WtHR, and body-fat percentage are four ways of assessing weight. Combining them may be the best way to get an accurate idea of whether a person should consider managing their weight.

Anyone with concerns about their weight, waist size, or body composition should speak with a doctor or nutritionist who can advise about suitable options.

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