We are more than one number

We are more than one number in a chart, whatever number that may be. When thinking about health from a biomedical, metabolic perspective, we are combination of many factors including blood pressure, fasted glucose and HbA1C, cholesterol levels like LDL and HDL, triglycerides, and body mass index (BMI). In this post, I'm going to take a quick look at what a few of these parameters do and don't tell us about health.

Body Mass Index (BMI)

BMI is a reflects body weight in relation to height. It doesn't reflect anything about lean muscle and body. It doesn't tell us anything about where body fat is distributed or if body fat is posing a potential risk to health. It is not useful with certain groups of people, namely athletes who engage in intense weight lifting/body building. They will end up classified as obese or even severely obese but have lots of muscle mass and very little fat mass.

There are many different BMI calculators available online. You will find that they all work the same and will give you the same numerical result as long as you input the same data. Pay attention to the units of measure that the program requests because sometimes it asks for weight and height in pounds and inches, sometimes it wants height in feet and inches, and sometimes it wants weight in kilograms and height in centimeters. There are websites that provide interpretive information. The quality of that information varies. Here are links to two BMI calculators from reputable sources:

• BMI Calculator - CDC

• BMI Calculator - Mayo Clinic

What is the purpose of using BMI as a screening tool?

The purpose of identifying people or populations at risk of disease is to offer early intervention or treatment to improve individual and community outcomes and quality of life. We know that overweight and obesity is associated with low-grade inflammation throughout the body. This inflammation increases the risk of chronic diseases such as cardiovascular disease and type 2 diabetes. Additionally, diets high in saturated fats and added sugars increase the risk of hypertension and cardiovascular disease. Body weight and BMI are quick and simple ways to identify people and groups that are at greater risk of disease. This helps doctors and public health officials reach out to them.

Body weight and BMI are components of a larger diagnostic picture. Alone these measures cannot diagnose, treat, or prevent any disease. Blood pressure readings, heart rate, blood cholesterol panels and blood glucose tests are common and routine screenings that together with body weight and BMI help health care teams and public health officials understand an individual's or community's health status.

When BMI was introduced into the health care and public health setting, it was not intended to be used by the general public as it is today. As I have said, on its own, the value of BMI is limited. But our access to BMI calculators and BMI charts is endless.

Changing the focus

We lack successful methods to support long term success for weight loss. At this time, 5-10% of people who lose weight maintain their weight loss for 5 years or more, and 1/3 of people who lose weight regain it within a year (1). We need to keep working to figure this out. We also need to reexamine our approach to weight loss and question if using weight focused goals that emphasize BMI is truly the best way to impact change and promote health (2).

The BMI calculation is not complicated and there are online calculators all over the Internet that make it even simpler. What used to be done by dietitians is done by everybody. We now have personal fitness apps with numerous features to help someone work their way towards their weight-targeted goals. I get it. Body weight and BMI are quick, easy, and inexpensive measures to assess and track. We are a results oriented society and if you increase physical activity and decrease caloric intake, you will see body weight go down. I know, easier said than done, but the numbers will change if you can do it. Doing it safely is less easy. Being able to do it and and then maintain it are other issues. People are complicated, messy, and carry a lot of baggage.

The vicious weight loss cycle of losing-gaining-losing weight has negative effects on health that include

• increased body fatness in the upper body (associated with more inflammation and greater health risk);

• reduced HDL (good) cholesterol;

• decreased muscle mass;

• and varying degrees of psychological harm.

Along with others, I promote metabolic health (2). Achieving metabolic fitness includes adequate nutrition, physical activity, rest/sleep, and stress management. For some people, this journey may involve weight loss. For some people, it may not. These components are far more important than a number on a scale and a BMI classification.

Resources

1. Kraschnewski JL, Boan J, Esposito J, Sherwood NE, Lehman EB, Kephart DK, Sciamanna CN.(2010) Long-term weight loss maintenance in the United States. Int J Obes, 34: 1644–1654.

2. Bacon L and Aphramor L, (2011) Weight science: Evaluating the evidence for a paradigm shift. Nutr J, 10:9.

What matters?

Your overall metabolic health matters and it is influenced by multiple factors:

• Blood pressure

• Heart rate

• Fasted blood glucose and HbA1C

• Cholesterol: LDL-cholesterol, HDL-cholesterol, Total cholesterol
  

For more information about cholesterol as well as links to other resources

• Triglycerides

• Physical activity

• Sleep per day (6-8 hours per day are recommended for adults)

• Adequate nutrition

• Body weight, BMI
  

For those people whose BMI classification places them in the overweight or obese category:

• losing 5-10% of body weight may improve blood pressure, heart rate, blood glucose, and cholesterol levels.

• Weight loss is considered safe at 1-2 lbs per week through a combination of calorie reduction (250 - 500 cals/day) and increased physical activity (250-500 cals/day extra)

If you have decided to embark on a lifestyle modification that involves more physical activity and mindful eating (eating with awareness), consider setting realistic, measurable, attainable goals that focus on your overall health and well-being. If you have not already done so, please get a complete physical and/or take advantage of a free health screening in your community before making any changes.

Some physicians also look at other parameters because of their role in obesity-associated inflammation and disease risk. If you have blood work done, you might see any of the following included in your lab results. These proteins are altered with obesity and inflammation and when metabolic health is improving, these proteins start to normalize. CRP is the most likely protein that you could see included, but the others are starting to show up as well.

• C-reactive protein (CRP)

• Interleukin-6 (IL-6)

• Adiponectin

• Leptin

• Plasminogen activating inhibitor (PAI-1)

Final Thoughts

• Small changes make a big difference. If you are overweight, losing 7-10% of your body weight can improve your metabolic health.

• What is your motivation behind losing weight? Is it to improve an aspect of your metabolic health, to look better, or to prepare for an upcoming event? How did you decide on how much weight you wanted to lose?

• Remember, BMI is one of many screening tools used to help people live healthier, longer lives. It is not the only thing that determines your health but it does help alert you and your doctor to whether your weight is putting you at an increased risk for health problems. You can reduce your risk by adopting lifestyle changes that include eating a balanced diet, engaging in regular physical activity, getting enough sleep, and managing stress.