BMI: What It Is, What the Numbers Mean and Why It Matters

Liam: The U.S. Preventive Services Task Force is a national panel of medical experts. It recommends screening adults 35 to 70 who have overweight or obesity for prediabetes and type 2 diabetes. The panel notes that a B M I of 23 or higher may be a better cut point for Asian American adults.

Claire: Thanks for joining us. You're listening to Between Visits, sponsored by Hope Health Network, a network of medical practices serving South Carolina. We dig into the medical and mental health topics that matter most to patients and the public.

Claire: I'm Claire, and this is episode 2. I'm going to quickly play our disclaimers, and then we'll get started!

Recorded disclaimer: This show is for entertainment, education and general information only. It's not medical advice, and listening doesn't make you a patient. Our hosts and guests are not real people, medical doctors or healthcare providers. We do our best, but we can be wrong, and our content can have errors and omissions. Talk with a licensed medical provider in your state before you make any decisions about your health or medical care.

Claire: In an emergency, call 911. In a crisis, call or text 988.

Claire: Joining me today is Liam, from our digital entertainment team. Welcome, Liam!

Liam: Thanks, Claire. Did you get any rest this weekend?

Claire: A little. I tried to sleep in, and my alarm had other ideas.

Liam: It always knows, doesn't it?

Claire: Today we're talking about BMI: What It Is, What the Numbers Mean and Why It Matters. Well, we're excited to get your thoughts on this important topic, Liam. Let's get started.

Claire: Today we're talking about B M I. You've probably seen those letters on a chart or heard them at a checkup. So let's start simple. What does it stand for?

Liam: It stands for body mass index. It's a number that measures your weight compared with your height.

Claire: That's it? Just how tall you are and how much you weigh?

Liam: That's it. It's one of the easiest first steps you can take for your health. It takes about a minute to find. And it gives you and your provider a place to start talking about weight, heart health and blood sugar.

Claire: Okay. Do I have to do math? Because I'll be honest, that's where you could lose me.

Liam: Here's the formula, just so you've heard it. It's your weight in kilograms divided by your height in meters squared.

Claire: And you've lost me.

Liam: Good news. You don't have to do any of that. The Centers for Disease Control and Prevention has an Adult B M I Calculator. You put in your height and weight, in feet and pounds or in metric units, and it works out the number.

Claire: Feet and pounds. Now we're talking. Is it for everybody?

Liam: It's meant for adults 20 and older. Children and teens use a different calculator.

Claire: So what does the number really tell me? Is it a diagnosis?

Liam: No, and that's an important point. The Centers for Disease Control and Prevention calls B M I a quick, safe and reliable screening measure.

Claire: Screening measure. What does that mean in regular words?

Liam: It's a first check. It helps decide whether to look more closely. B M I is not meant to diagnose a disease or illness, and it should be looked at along with other things.

Claire: So it's a first look, not a final answer.

Liam: Exactly. Think of it as a starting point, not a verdict.

Claire: Okay, let's get to the numbers. Walk me through them slowly, because I think this is where people get confused.

Liam: Sure. These are the adult groups from the Centers for Disease Control and Prevention. A B M I below 18.5 is called underweight.

Claire: Okay. And the next one?

Liam: From 18.5 to 24.9 is called a healthy weight.

Claire: And after that?

Liam: From 25 to 29.9 is called overweight. And 30 or higher is called obesity.

Claire: I've also heard people talk about classes of obesity. What's that about?

Liam: Obesity is split into three classes. Class 1 is a B M I of 30 to 34.9. Class 2 is 35 to 39.9. And class 3 is 40 or higher.

Claire: Does class 3 have another name? I feel like I've heard a few.

Liam: It does. The Centers for Disease Control and Prevention calls class 3 severe obesity. You may still hear the term morbid obesity for that same range.

Claire: How many people are we talking about? If someone's listening and thinking about their own number, are they the only one?

Liam: Far from it. About 4 in 10 U.S. adults had obesity from August 2021 to August 2023. That comes from the National Center for Health Statistics, which is part of the Centers for Disease Control and Prevention.

Claire: Four in 10. So if this is on your mind, you have plenty of company.

Liam: You do.

Claire: So why does the number matter? What's the worry here?

Liam: The National Institute of Diabetes and Digestive and Kidney Diseases links overweight and obesity to many health problems. Those include type 2 diabetes, high blood pressure, heart disease and stroke.

Claire: That's already a lot.

Liam: There's more on the list. A sleep problem called sleep apnea, a kind of arthritis called osteoarthritis, gout, kidney disease and certain cancers.

Claire: I've heard people mention fatty liver too. Is that on there?

Liam: It is. That's when extra fat builds up in the liver. You may hear it called M A S L D. The institute says it's more common in people with obesity.

Claire: Okay, that's a heavy list. Is there any good news in here?

Liam: There is. A little weight loss can go a long way. The National Heart, Lung, and Blood Institute says health professionals recommend losing 5 to 10 percent of your starting weight over about 6 months.

Claire: Put that in real pounds for me.

Liam: The Centers for Disease Control and Prevention gives an example. For a 200-pound person, 5 percent is 10 pounds.

Claire: Ten pounds. That sounds a lot less scary than I expected.

Liam: And losing even 3 to 5 percent can lower blood sugar and triglycerides. Triglycerides are a type of blood fat. It can also reduce the risk of type 2 diabetes.

Claire: So I don't have to reach some perfect number before it can help.

Liam: That's a fair way to put it. Your provider can help you pick a goal that fits you.

Claire: Let me push back a little. What about someone who's all muscle? Couldn't they get a high number and be told they have a problem? That doesn't seem fair.

Liam: That's a good question. The Centers for Disease Control and Prevention notes that B M I doesn't tell fat apart from muscle and bone. It also doesn't show where in your body you carry fat.

Claire: So the number can't see everything.

Liam: Right. It's a starting point, not the whole picture.

Claire: Does it matter where you carry it?

Liam: It does. The National Heart, Lung, and Blood Institute says that if most of your fat is around your waist rather than your hips, your risk of heart disease and type 2 diabetes is higher.

Claire: Is there a number for that too?

Liam: There is. A waist of more than 40 inches for men, or more than 35 inches for women, raises risk.

Claire: And how do I measure it? I have a feeling I've been doing it wrong.

Liam: Stand up and wrap a tape measure around your middle, just above your hipbones. Then read it just after you breathe out.

Claire: Just after you breathe out. So no holding in your stomach.

Liam: No holding it in. Just breathe out and read the tape.

Claire: Are these numbers the same for everyone?

Liam: Not always. The cut points can differ by background. A cut point is the number where people start to look closer.

Claire: Can you give me an example?

Liam: The U.S. Preventive Services Task Force is a national panel of medical experts. It recommends screening adults 35 to 70 who have overweight or obesity for prediabetes and type 2 diabetes. The panel notes that a B M I of 23 or higher may be a better cut point for Asian American adults.

Claire: So 23 instead of 25.

Liam: Possibly. The panel says it may be a better cut point. Medicare's Diabetes Prevention Program also uses 23 or more for people who are Asian, instead of 25 or more. You can ask your provider which number applies to you.

Claire: Okay. So I find my number. Now what do I do with it?

Liam: It depends on where it falls. If your B M I is in the overweight range, talk with your provider about your other risks. That means things like blood pressure, blood sugar and waist size. Then you can decide on next steps.

Claire: And if it's 30 or higher?

Liam: The same panel recommends that clinicians offer you, or refer you to, an intensive behavioral program. That's a program built around healthy eating, physical activity and support.

Claire: Intensive. That word makes me picture a boot camp.

Liam: No whistles required. It means steady support over time. The programs the panel looked at aimed for at least 5 percent weight loss, and most had 12 or more sessions in the first year.

Claire: So it's ongoing help, not one talk and good luck.

Liam: Right. A provider can talk with you about whether it's a good fit.

Claire: If someone's not sure how to bring this up at a visit, what could they ask?

Liam: Here's a simple one. What are my B M I and my waist size, and what do they mean for my health?

Claire: I like that. Two numbers, one question. You could write that down and take it with you.

Liam: You could. Your height, weight and waist can be measured at a visit. Then your provider can look at your number along with your blood pressure, blood work and health history.

Claire: That makes sense. Okay, before we wrap up. If people only remember a few things from today, what should they be?

Liam: First, B M I is a quick first check. It's not a diagnosis.

Claire: Okay. What else?

Liam: Second, it can't tell fat from muscle, and it can't show where you carry fat. So ask about your waist too.

Claire: And one more?

Liam: Small changes can count. Losing even 3 to 5 percent of your weight can lower blood sugar and triglycerides. Ask your provider what goal fits you.

Claire: That's really helpful. Thank you for walking us through this.

Liam: Thanks for having me, Claire. I hope it helps someone.

Claire: This episode is sponsored by Hope Health Network. Its member practices all have providers experienced in managing weight and B M I, or can refer you to a network provider who is. Hope Health Network medical practices provide evidence-based medical care and include Hope Integrative Medicine, Hope Medical Associates, Hope Behavioral Medicine and Hope Addiction Medicine. To learn more, go to Hope Health Network dot com. That website, along with appointment links for all four practices, is in the description of this episode.

Claire: One last reminder. In an emergency, call 911. In a crisis, call or text 988.

Claire: This podcast is a production of Hope Health Network Media.

Claire: You've been listening to episode 2 of Between Visits, BMI: What It Is, What the Numbers Mean and Why It Matters. Thanks for hanging out with us. See you next time!