Feeling motivated to lose weight so you can improve your health? Healthcare providers often tell us that whittling that waistline and getting down to a lower weight will also mean a lower risk for Type 2 diabetes, heart disease and cancer.
The links between higher body weight and chronic illness have strong scientific support, but there are a growing number of skeptics with a different explanation. Here’s their side of the story: it’s fitness level rather than weight which leads to higher rates of what we typically believe are weight-driven conditions — hypertension, heart disease and diabetes to name a few. So, does that mean an overweight marathoner has the same risk of developing these conditions as a normal weight person? Let’s explore the debate.
How Do I Know if I’m Fit but Overweight?
You may be wondering if you’re fit, overweight or both, so, let’s get those definitions squared away. Body mass index (BMI) is the ratio between your weight and your height, and it’s used to estimate how much body fat you have. Here’s the formula for BMI:
BMI = [Weight in Kilograms] / [Height in Meters]2
An even easier way to get your BMI is through your Zipongo account. Just enter your height and current weight, and we’ll do the calculations for you. Once you have your BMI, you can see where you fall on the spectrum:
| BMI | Category |
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Normal weight |
| 25.0 to 29.9 | Overweight |
| Over 30.0 | Obese |
Fitness is more complicated because there’s more than one way to measure it. Here are three of the most common fitness metrics:
- Physical Fitness is how much exercise you get and how often.
- Cardiovascular Fitness is how much exercise can you tolerate in a given time period.
- Metabolic Fitness is how efficiently your muscles are able to metabolize (use) fuel like fat and glucose during exercise. One way metabolic fitness is measured is by looking at your lab results to see if your blood pressure, blood cholesterol and blood sugar are in normal range.
Since researchers can choose which of these measures to use for their studies, “fitness” doesn’t always mean exactly the same thing. It’s important to keep this in mind if you’re comparing the results of several studies.
Fitness Versus Weight
At one end of the spectrum you have experts who say that weight and BMI can predict the risk of getting a health condition down the road. For example, did you know that weight is the single best predictor that someone will develop diabetes in their lifetime?
At the other end of the spectrum, the evidence is also compelling. Not being fit is considered a predictor of disease. So where’s the evidence that fitness helps? A prospective cohort study of 21,925 men aged 30-83 found that fit men had a lower risk of dying compared to their unfit normal-weight, overweight or obese counterparts. Furthermore, the fat-but-fit men had an eight percent lower risk of dying compared to lean-but-unfit men. That’s a small enough difference that other studies have found mixed evidence as to whether being fit will protect you from the health consequences of being overweight. The Nurses Health Study of 116,564 women found that obese and active women still had a higher risk for death compared to lean active women.
Expect the controversy to continue even after the latest and largest findings by researchers: metabolically healthy obese adults have markedly higher risk for heart disease (e.g., heart attack, stroke and heart failure) compared to metabolically healthy, normal weight adults. This data comes from 3.5 million health records of adults 18 and over.
The Takeaway
The data suggests that you can be fit and overweight, but this may be rare depending on how you define fitness. If cardiovascular fitness is the measure, then just 17.4 percent of overweight and 8.9 percent of obese adults would qualify as highly fit. Both fitness and weight play an independent role in your health. No matter what size you are, a good diet and regular exercise will help you reach better health.
