We all probably know someone who is overweight but who is nevertheless energetic, flexible, and full of life. Consider professional football players. A recent survey found that two out of three had a BMI (body-mass index, a measure of weight relative to height) of 30 or above, while one out of three had a BMI at 35 or more. A BMI above 30 is technically considered obese. And yet these athletes possess a speed and agility way beyond that of most of us.
Because some individuals seem to be both obese and fit, some analysts have coined the term “healthy obesity” to describe people who are clinically overweight but also what’s known as “metabolically healthy” — that is, they do not meet the definition of having what experts call “metabolic syndrome.” Metabolic syndrome is a group of conditions that occur together and increase a person’s risk of type 2 diabetes, heart disease, and stroke. Among these conditions are high blood sugar, high blood pressure, extra fat around the waist, and elevated levels of cholesterol or triglycerides.
A new report from researchers in the United Kingdom and reported in the medical journal Diabetologia, however, casts doubt on whether “healthy obesity” really exists.
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The researchers got their data from what’s known as the UK Biobank, which describes itself as “a large-scale biomedical database and research resource, containing in-depth genetic and health information from half a million UK participants.” Since it was launched in 2006, over 20,000 researchers have been approved to use the database for their studies.
The authors of the new report on “healthy obesity” identified 381,363 people and followed their health status for a median of 11 years. The subjects’ heights and weights were measured by trained staff members and those subjects who had a BMI of 30 or more were categorized as obese. Of the 381,363 individuals, about one out of 10 (35,103) were classified as both obese and metabolically healthy. To be rated as metabolically healthy, the subjects had to be in the normal range for four out of six metabolic markers — blood pressure, blood sugar (as measured by an HbA1c test), HDL (“good”) cholesterol, LDL (“bad”) cholesterol, C-reactive protein, and triglycerides. The researchers also rated 59,376 people as both obese and metabolically unhealthy, while 208,625 were found to be metabolically healthy and not obese.
For their analysis, the researchers used what are known as “proportional hazards models” to search for any associations between obesity, metabolic health, and health outcomes. A proportional hazard model is a common method in medical statistics to study the relationship between certain variable factors and patient health and mortality. The researchers also adjusted for other influential factors, such as age, sex, ethnicity, alcohol intake, smoking, diet, and physical activity.
Metabolically healthy people with obesity at higher risk of various health conditions
It came as no surprise that obese subjects who were metabolically healthy were at lower risk of unwelcome health consequences than the metabolically unhealthy obese subjects. The metabolically healthy obese subjects, for example, had about one-third the risk of diabetes, although the researchers did point out that more than one out of four of the metabolically healthy obese subjects became metabolically unhealthy within three to five years. The most striking discovery came when comparing metabolically healthy obese people to metabolically healthy people who were not obese. Here, it was found that subjects who were metabolically healthy and obese were at a significantly higher risk of diabetes, cardiovascular disease, heart failure, respiratory diseases, and death from all causes.
What does this mean for the concept of “healthy obesity”? Well, as the researchers explained, the “key point … is that the risk of many important outcomes, such as heart failure and respiratory disease, is elevated in people with obesity even if they have a normal metabolic profile. Using the label ‘metabolically healthy’ to describe this group in clinical medicine is misleading and therefore should be avoided. These findings … suggest that weight management could be beneficial for people with obesity even if they do not currently show abnormalities in their metabolic profile.”
Want to learn more about weight management? Read “Tried and True Weight-Loss Techniques,” “Losing Weight Without Feeling Hungry: Eight Tips,” and “Why Can’t I Lose Weight?”
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