Body Mass Index: The Calculation And Its Purpose

Are you aware that there is a way to measure your body composition, including how much fat and muscle you have, without using complicated or expensive equipment? The Body Mass Index (BMI) is a calculation considering your height and weight. BMI can be a good indication of whether you're at a healthy weight or not.

Learn more about BMI and determine if you're in a healthy range.

Body Mass Index: What Is It And What Does It Mean?

BMI (Body Mass Index) is a simple tool that medical professionals use to calculate an individual's body fat using height and weight. The BMI can be calculated using a table or chart that depicts BMI as a function of height and mass using colors or contour lines to represent different BMI categories and may also use other units of measurement.

Based on tissue mass (muscle, bone, and fat), height, and BMI, a person is often classified as underweight, normal, overweight, or obese.

The four main adult BMI categories are:

Often, a person's BMI correlates to their body fat; the higher the figure, the more body fat you may have. Although BMI is frequently used as a caliber of body fatness, it measures extra weight rather than excess fat. It serves as a substitute for actual body fat measurements.

Furthermore, studies have demonstrated a relationship between BMI levels, future health concerns, and body fat. A high BMI indicates future illness and mortality. BMI is a suitable measurement for assessing the danger of obesity to health.

BMIs below 20 kg/m2 and above 25 kg/m2 have been linked to higher all-cause death rates, with the risk rising as BMIs move away from the 20-25 kg/m2 range.

How Does Body Mass Index Work?

Knowing your BMI helps either maintain your weight or reduce or increase your weight to have a healthy body and minimize health risks due to being overweight or obese.

When there is an energy imbalance, people acquire weight. For the body to function, food must provide a specific amount of energy, the source of which is calories. When you consume the same calories your body utilizes or burns daily, your weight will often remain stable. Over time, weight gain will occur if you consume more calories than you expend.

Unbalanced energy intake is undoubtedly one of the main causes of weight gain. However, genetics, the foods you eat, and the amount of activity you get play a major role in determining your ideal weight. It's critical to reduce your BMI if it is high to maintain a healthy weight.

How Is Body Mass Index Calculated?

Both adults' and children's BMIs are determined in the same manner. The following formulas are used in the calculation:

1.  Kilograms and Meters (or Centimeters)

Formula: Weight (kg)/[Height (m)]2

BMI is calculated using the metric system, which divides weight (kilograms) by height (meters) squared. Height is often measured in centimeters; thus, multiply the centimeter value by 100 to get the equivalent height in meters.

Example: If you are 60 kg with a height of 164 cm (1.64 m), then your BMI is

     60/(1.64)2 = 22.3 (Normal)

2.  Pounds and Inches

Formula: Weight (lbs)/[Height (in)]2 x 703

By multiplying the answer by a conversion factor of 703, the BMI is calculated by dividing the weight in pounds (lbs) by the height in inches (in) squared.

Example: If you are 150 pounds and 5'5″ (65″) tall, then your BMI is

     [150/(65)2] x 703 = 24.96 (Overweight)

You may calculate your body mass index here if you wish to check yours.

What Is The Purpose Of The Body Mass Index?

BMI is used by medical professionals as a screening tool for several diseases as well as to help diagnose different weight categories.

BMI is generally used to check for health concerns. You may have an increased chance of getting the following illnesses if your BMI is under 18.5 (underweight):

  • Anemia
  • Malnutrition
  • Infertility
  • Weak immune system (contributes to frequent infections and illnesses)
  • Osteoporosis/bone loss

Your healthcare professional will probably request certain blood tests and other tests if you are underweight to assess your general health and determine whether you are malnourished.

The following conditions are generally more likely to affect you if your BMI is higher:

  • Type 2 diabetes
  • Sleep apnea
  • High blood pressure
  • Heart disease
  • Dyslipidemia
  • Stroke
  • Osteoarthritis
  • Gallstones/bile stones
  • Depression and other mental health conditions
  • Certain cancers, including breast, endometrial, colon, and gallbladder

Remember that you could have any of the aforementioned health issues without a high BMI. The same is true for having a high BMI without any of these disorders. The development of these disorders is greatly influenced by genetics and other elements, such as cigarette smoking, alcohol consumption, and many more.

Your doctor will likely request specific blood tests, such as a comprehensive metabolic panel and lipid panel, to evaluate your general health if your BMI indicates that you may be obese.

What Is Body Mass Index (BMI) Considered Overweight?

Adults with BMIs between 25 to 29.9 kg/m2 are considered overweight.

Fixed BMI cut-off points for adults determined from morbidity and mortality data define the categories of overweight and underweight. Adults with BMIs of 25.0 kg/m2 and above (85th to less than 95th percentile) are considered overweight and above 30.0 kg/m2 (greater than 95th percentile) obese with higher relative mortality risk.

Statistically, you are more likely to develop various diseases if you are overweight. For instance, the risk of death rises by 20% to 30% as BMI rises from 25 to 27 kg/m2. As BMI rises above 27 kg/m2, the risk of death rises more steeply by 60%.

What Is The Normal Or Healthy BMI For Adults?

The normal or healthy BMI for adults is 18.5 to 24.9 kg/m2 (between the 5th and 85th percentile). This number will vary according to an individual's age, gender, and stature.

A healthy body fat percentage aids in the absorption of vitamins and minerals. It also serves as your body's energy source, aids in controlling body temperature, and shields your organs.

Which Body Mass Index Would Require Hospitalization?

Older people aged 65 and above with a BMI less than 24 kg/m2 or any degree of weight loss would require hospitalization to reduce nutrition-related complications.

According to a study, abnormally low weight or excess body fat is linked to a greater hospitalization rate. In contrast to patients of normal weight, the incidence of hospitalization was reduced for underweight patients and greater for those of normal weight. The chances of hospitalization were lower as one's weight increased.

On the other hand, underweight people were more likely to be hospitalized when they lost weight. Underweight patients had a higher chance of being hospitalized, whereas obese and overweight patients had a lower chance. There was a startlingly high hospitalization rate in underweight people who experienced short-term weight loss.

Foods To Maintain The BMI

It's important to watch your caloric intake to maintain weight, and some foods help. In addition to helping you keep a healthy weight, eating well is essential for excellent health. How we eat is just as crucial to our health as what and how much we consume.

Foods that you can add to your routine and choose minimally processed whole foods:

  • Whole Fruits: Eating whole fruits will provide you with all the available nutrients, and fiber content will help you with digestion.
  • Whole Grains: Whole wheat, brown rice, steel-cut oats, and quinoa are high-protein grains and minerals like iron, magnesium, and fiber.
  • Vegetables: Add a colorful variety, except for potatoes, into your diet since these are rich sources of vitamin A, vitamin C, potassium, and antioxidants.
  • Nuts, beans, seeds, and other sources of protein, such as poultry and fish
  • Plant oils – coconut, olive, sunflower, and various vegetable oils
  • Consume water or other calorie-free natural beverages

Limit Or Avoid These Foods And Drinks

  • Potatoes (baked or fried)
  • Red meat (beef, lamb, pork) and processed meats (bacon, salami, ham, sausage)
  • Fruit juice (a small amount or a glass per day)
  • Sugar-sweetened beverages (fruit drinks, soda, sports drinks)
  • Refined grains (white pasta, white bread, white rice) and sweets
  • Other extensively processed foods, such as fast food

Healthy Weight/BMI Checklist

  • Adopt behaviors that will prevent you from overeating and avoid some of the high-calorie, low-nutrient foods most strongly associated with weight gains, such as sugar-sweetened beverages, refined grains, and potatoes.
  • Although skipping a meal could seem like a simple method to reduce calories, skipping breakfast usually backfires when hunger strikes again in the middle of the day, frequently resulting in overeating.
  • Eat slowly and deliberately. Making the healthiest food and beverage selections feasible will help you avoid consuming unnecessary calories. Take some time to consider why you are eating. Have a slice of fruit instead of a complete meal, or choose something else. To fully enjoy the meal you are eating, concentrate all your senses on the food you are eating.
  • Nothing is more crucial to maintaining a healthy weight and being in good health than regular exercise and eating a portion of nutritious food. Physical activity would be the panacea for good health if there were one.
  • All age groups should prioritize getting enough exercise and limiting “sit time,” particularly when watching television.
  • About 2.5 hours of moderate activity (brisk walking or slow cycling) or 1.25 hours of strenuous activity per week are recommended for excellent health (running, fast bike riding). Try working up to 150 minutes of aerobic activity at moderate intensity or 75 minutes vigorously per week.
  • Avoid eating foods cooked outside of the home, such as restaurant meals, fast food, and other items, typically contain larger quantities and are less nutrient-dense than meals we prepare at home.
  • A good night's sleep is essential to excellent health and may also help you maintain a healthy weight, as more and more research shows. Each individual can have quite different wants.

The Key Takeaway

Body Mass Index, or BMI, measures body weight that considers height and weight. A high BMI may be a sign of being overweight or obese. While there are some drawbacks to using BMI as the only measure of health, it can be a helpful tool in determining whether you need to make changes to your diet or exercise routine.

Knowing your BMI can help you make healthy choices about your weight and health.












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