With a new year comes a renewed effort by many resolution makers to determine their healthy weight. But how do we go about doing this? There are calculators online that could categorize you as “overweight,” especially if you happen to be over that crucial “25” BMI benchmark.
A BMI “body mass index” quickly configures a status number (18.5-24.9 considered “normal”) using your height and weight. But a healthy weight is not just about a number. It amounts to a collection of data obtained by a primary physician, and if needed, a dietitian, to monitor any weight-loss program, according to Melissa Franco, D.O. , a family medicine physician with Baptist Health Primary Care .
“We do get a lot of patients in January coming in for their physicals, and some of them want to know how to get into shape and lose weight,” said Dr. Franco. “They need support and encouragement, but also someone to hold them accountable.”
Primary care practices are increasingly turning to “care coaches,” — not a physician but someone with a clinical or nursing background — to monitor a person’s progress in developing a healthier diet and an exercise program over a period of months. Dr. Franco will also refer patients to a dietitian to get started.
But first comes a physical and blood workup to determine if excessive weight has created underlying heart disease risk factors, such as high blood pressure, high cholesterol or high blood sugar readings that can lead to type 2 diabetes, also known as “prediabetes.”
Your BMI and Body Fat
Dr. Franco and most primaries rely on the BMI for an initial assessment. A BMI does not measure body fat directly, but many studies have shown that it is a good reflection of a person’s body fat composition. A BMI is inexpensive and easy to use, and it establishes a reliable weight category for physicians, dietitians and physical trainers who assist individuals in weight management and reducing risk factors for heart disease and other common conditions.
“We generally use the BMI to estimate body fat and determine if a patient is above that 25 reading,” says Dr. Franco. “In some cases, a BMI doesn’t tell the whole story. For example, someone who works out with weights frequently, such as athletes or body builders, have higher muscle mass than the average person. That would skew the BMI higher, even though that person would not be considered overweight.”
After taking into consideration muscle mass, the correlation between the BMI number and body fatness is fairly strong, says the U.S. Centers for Disease Control and Prevention (CDC). But the correlation varies by sex, race, and age. These variations include the following CDC examples:
- At the same BMI, women tend to have more body fat than men.
- At the same BMI, older people, on average, tend to have more body fat than younger adults.
- Highly trained athletes may have a high BMI because of increased muscularity rather than increased body fatness.
Calculating Your BMI
To calculate your BMI, the CDC offers a calculator . Or you can look up your height and weight in the CDC’s BMI Index Chart. Here are general guidelines.
- If your BMI is less than 18.5, it falls within the “underweight” range.
- If your BMI is 18.5 to 24.9, it falls within the “normal” or Healthy Weight range.
- If your BMI is 25.0 to 29.9, it falls within the “overweight” range.
- If your BMI is 30.0 or higher, it falls within the “obese” range.
For adults over 20 years of age, the BMI is interpreted using these standard weight categories that are the same for all adults, both men and women. For children and teens, however, BMI is both age- and gender-specific. For more information, see the CDC’s Child and Teen BMI Calculator .
The CDC gives this example: A person with a height of 5 feet, 9 inches would fall into the “normal” weight range if he or she weighs between 125 pounds and 168 pounds. But if this same individual weighs between 169 pounds and 202 pounds, he or she is classified as “overweight.” If the person weighs over 203 pounds, he or she is categorized as “obese.”
Weight and Risk Factors
Individuals who are overweight and obese are at increased risk for many diseases, including the following listed by the CDC:
- Dyslipidemia (for example, high LDL cholesterol, low HDL cholesterol, or high levels of triglycerides)
- Type 2 diabetes
- Coronary heart disease
- Gallbladder disease
- Sleep apnea and respiratory problems
Dr. Franco points out that someone with a BMI level above 25 could benefit significantly by just losing 10 pounds. Sometimes that’s enough to get a person under 25.
“First of all, people should know where they’re at when it comes to that 25 BMI standard,” she says. “That BMI calculation may be a bit strict, but it’s generally effective. I’ve seen patients get off blood pressure or cholesterol medication after losing just a few pounds and maintaining a healthier lifestyle.”