What Exactly is BMI and Why Should I Care About Mine?

The body mass index, commonly abbreviated as BMI, is a calculation that uses your height and weight to estimate your body fat in adults. It’s used as a screening tool to indicate if you may be underweight, overweight, or obese.

BMI is actually something you should pay attention to because it can provide insight into potential health issues. Carrying excess body fat raises your risks for several serious diseases, including heart disease, type 2 diabetes, high blood pressure, certain cancers, kidney disease, fatty liver disease, pregnancy complications, and even some mental health conditions like depression.

Specifically, having a BMI in the overweight or obese ranges bumps up your odds for developing those conditions. Maintaining a BMI in the healthy range – which is 18.5 to 24.9 – doesn’t guarantee you won’t get those diseases. However, it does mean you have better chances of dodging them.

How is BMI Determined Exactly?

Calculating your BMI is super simple and requires just two measures:

• Your weight in kilograms
• Your height in meters

To determine BMI, just divide your weight (kg) by your height squared (m2). Yep, it’s math, but don’t let that scare you off. There are plenty of easy online BMI calculators that do the number crunching for you instantly.

Or you can use this formula:

BMI = kg / m2

For example, if you weigh 150 pounds (68 kg) and you’re 5’4” (1.63 m) tall, your BMI would be:

68 ÷ (1.63)2 = 25.6

A result between 18.5 and 24.9 would fall into the healthy BMI range.

The Drawbacks of BMI

Despite BMI being an easy, cheap way of evaluating body fat, it does have some limitations. Here’s why it doesn’t paint a complete picture:

• It doesn’t distinguish between fat, muscle mass, or bone density. So very muscular people may have overweight or obese BMIs without actually having excessive fat.
• Genetics and age influence BMI too. Some racial groups and older adults tend to have higher BMIs unrelated to body fat.
• BMI doesn’t reveal where you store fat. Carrying excess visceral fat internally around the organs hikes disease risks more than subcutaneous fat under the skin.

So while BMI works fine for the general population, it’s not accurate for all individuals. An athlete or older person could have a high BMI but actually be very healthy. That’s why getting your body composition tested or having a doctor assess your health is smarter than fixating on BMI alone.

Health Risks of High and Low BMI Values

Being overweight or obese as determined by BMI does correlate to higher chances for all sorts of diseases. But even having a BMI slightly above the normal limits markers you for potential issues.

Risks of Being Overweight

Having a BMI falling into the overweight range of 25 to 29.9 raises your odds for:

• Heart attack, heart failure, and stroke
• High cholesterol and blood pressure
• Insulin resistance and type 2 diabetes
• Gallstones
• Osteoarthritis
• Sleep apnea and breathing issues
• Certain cancers like breast, colon, esophagus, pancreas, kidney, thyroid, endometrium
• Complications during pregnancy
• Mental conditions including depression and anxiety

Risks of Being Obese

Tip the scales into the obese BMI territory of 30+ and you’re even more likely to develop:

• Coronary heart disease and congestive heart failure
• Type 2 diabetes and metabolic syndrome
• High blood pressure
• Liver and gallbladder disease including fatty liver disease and gallstones
• Reproductive issues and complications during pregnancy
• Osteoarthritis
• Breathing problems including sleep apnea
• Certain cancers like breast, colon, esophagus, pancreas, kidney, thyroid
• Mental health disorders

Risks of Being Underweight

On the flip side, having an underweight BMI under 18.5 could indicate:

• Nutrient deficiencies
• Weakened immune system
• Osteoporosis
• Fertility issues such as missed or stopped periods in women
• Development issues in teens

Maintaining a healthy BMI protects you from all those nasty conditions. It also leads to perks like:

• Better athletic performance
• More energy
• Improved mobility
• Overall enhanced wellbeing

Pretty convincing reasons to stay within the ideal BMI range!

Tips for Improving Your BMI

Want to slim down or bulk up to reach a healthier BMI? Here are some practical suggestions:

To Lose Weight

• Cut back on added sugar, refined carbs, fried foods, and sweetened drinks which pile on empty calories
• Fill up on non-starchy veggies, fruits, whole grains, beans, lentils, nuts, seeds, fish, poultry, eggs, veggie oils like olive and avocado
• Stay adequately hydrated by sipping water, unsweetened tea, black coffee
• Monitor portions at meals and snacks
• Engage in regular aerobic activity like walking, jogging, cycling, swimming
• Build muscle with strength training 2-3x a week
• Aim for a modest weight loss of 1⁄2 to 2 pounds weekly

To Gain Weight

• Consume more healthy complex carbs and protein – think whole grains, starchy vegetables, beans, lentils, nuts, seeds, eggs, meats
• Snack frequently between meals
• Drink nutritional shakes or smoothies
• Choose nutrient-dense foods over empty calories
• Engage in strength training 4-5x a week to build muscle
• Aim for a gradual weight gain of 1⁄2 to 1 pound weekly

Adjusting your diet and fitness routine facilitates weight loss or gain to land in that healthy BMI zone. But don’t become overly fixated on the number itself. BMI is simply a screening guideline.

The Bottom Line on BMI

While the body mass index isn’t completely precise, it still acts as a decent indicator for body fat and health risks in the average adult. Carrying excess body fat hikes your chances for all kinds of life-threatening and life-limiting diseases. It may also hamper your quality of life.

But you shouldn’t obsess over BMI alone. Even if you tip the scales into the overweight or obese zones, you could still be metabolically healthy if you follow an otherwise sound lifestyle. What matters most is keeping active, eating well, managing stress, connecting socially, and tending to preventative healthcare.

Focus on feeling energized, flexible, strong, and at home in your body. The number on the scale or BMI calculator result doesn’t fully define your health. But using it as a cue to adopt healthier behaviors can guide you towards an enhanced sense of wellbeing.