Prediabetes: Why Being a Healthy Weight Doesn't Protect You

Written by Susan McQuillan, MS, RDN, CDN

While obesity is a top risk factor for the development of prediabetes, diabetes, and other chronic health problems, you can still develop these conditions at a healthy weight (having a body mass index (BMI) between 18.5 and 24.9). In fact, more than 18% of healthy weight American adults age 20 and older have been found to have prediabetes, a figure that increases to more than 33% when looking only at those aged 45 and older.1

Are You At Risk?

If you are what health experts call “metabolically unhealthy,” you have reason to be concerned. That means, if you have high blood pressure, high blood fats (triglycerides), high blood sugar, low HDL (protective) cholesterol, and/or insulin resistance, you are at increased risk of diabetes regardless of your weight. The more of these abnormalities you have, the higher your risk.2

Researchers are just beginning to find genetic evidence linking blood fats, fasting insulin levels, and body fat proportions to type 2 diabetes and other health issues in people who develop prediabetes at a normal or healthy weight.3 In addition to your genetic profile, or family health history, many other factors add to your individual risk of developing diabetes, including age, sex, and ethnicity. Unfortunately, these are all factors out of your control.

What you can control are the lifestyle choices you make that help determine whether or not you develop high blood sugar, high blood pressure, or other clinical signs of increased diabetes risk. When you are metabolically unhealthy you are considered “metabolically obese,” because you have some or all of the same risk factors as someone who is severely overweight. And just like someone who is overweight, you must be careful about what you eat and get plenty of exercise in order to stay as healthy as possible.

What the Science Says

One large-scale, European population study4 followed thousands of men and women over time in order to identify and characterize metabolically-unhealthy-yet-normal-weight individuals who later developed diabetes. The researchers found that being male, having high blood pressure, being a former smoker, and being less physically active were the traits that put normal-weight people at particularly high risk of developing diabetes.

These researchers also noted that some of the clinical risk factors found in study participants who ultimately developed diabetes, such as blood pressure and A1C, may have been higher than normal when first measured, but were still considered within normal range. That’s why it is important to pay attention to lab results in the high-normal range. (Note: A normal fasting blood (glucose) test is less than 100 mg/dl, prediabetic is 100-125 mg/dl and diabetes is usually diagnosed at 126+) Lifestyle factors such as poor diet choices and lack of exercise can also be early indications of increased risk. 

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Another study published in 2017 by researchers at the University of Florida5 was among the first to clearly link prediabetes in normal-weight adults (ages 20 and over) to a lack of physical activity. The researchers pointed out that lack of exercise results in changes in body composition increased blood glucose levels and reduced insulin sensitivity, all of which may be responsible for the development of prediabetes, even in people who aren’t overweight. Although risk levels were higher overall for those who were less active, this study also found the association to be more significant in men than in women, and in people age 45 and older, than in those ages 20 to 44. Follow up studies are necessary to determine exactly how much and what types of physical activity can best improve symptoms such as abnormally high blood sugar in men and women who are at a healthy weight.

What You Can Do

Whether you’ve been diagnosed with prediabetes, or you have risk factors associated with developing prediabetes, follow the exercise advice given by the American Diabetes Association6 to reduce the amount of time you spend sitting and increase the amount of time you spend moving throughout each day. If your job or lifestyle has you sitting most of the day, get up every 30 minutes or so, to do some stretches or take a short walk. That’s in addition to aiming for 30 minutes of aerobic exercise each day.

Although you don’t have to lose weight, your diet may need updating. That means focusing on what you eat, even if you don’t have to focus on how much you eat. A prediabetic diet is pretty much the same as a diet for managing diabetes. Be sure your meals and snacks are balanced to include foods from a variety of food groups.  Avoid processed foods and junk foods that contain added sugars, and also the “white carbs,” which include plain white rice and any foods made with white flour or white sugar. Instead, plan your meals and snacks to include healthy, high-fiber carbs like legumes, whole grains and whole-grain products, fresh fruits and vegetables, along with healthy sources of protein and fat, such as lean meats, seafood, soy products, nuts and seeds, and olive oil. Click here for more diet and exercise tips for people with prediabetes.

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