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According to a new Canadian study, obesity does not increase the risk of death if there are no other metabolic risk factors present. So, does healthy overweight actually exist?
Obesity: Cause, effect, or both?
Overweight is usually associated with certain health risk factors. Think of things like blood pressure, blood sugar, and insulin regulation. Also consider cholesterol, triglycerides (fats), and waist circumference. Sometimes it can be a consequence of overweight, other times the cause, and sometimes both. It depends on who you ask, at least.
The terms ‘healthy overweight’ or even ‘healthy obesity’ are quite controversial. Some researchers argue that there is no such thing as ‘healthy overweight’, let alone when it falls into the obesity category. Last year, I wrote an article following a British study that led to that conclusion. If people had three or more of the so-called metabolic risk factors, the risk of heart disease doubled. Weight didn’t matter. This might lead you to think that the metabolic risk factors themselves pose the danger, not necessarily the overweight.
When comparing in the “healthy” group (based on risk factors), overweight was found to cause a 26 percent higher risk of heart disease. For obesity, that risk was 28% higher.
“Healthy overweight doesn’t exist”
These researchers also argued that healthy overweight doesn’t exist. Everyone with overweight should be helped to lose weight, even if there are no (other) risk factors present.
Our findings suggest that if a patient is overweight or obese, all efforts should be made to help them get back to a healthy weight, regardless of other factors
But if you’re considered “unhealthy” if you have three or more of the metabolic risk factors, does that mean you’re healthy if you have ‘only’ one or two risk factors? I wondered if a doctor would suggest that your overweight seems entirely harmless because you ‘only’ have high blood pressure and elevated blood sugar.
“Healthy obesity exists”
And that’s precisely the point other researchers are making now:
… most studies have defined metabolic healthy obesity as having up to one metabolic risk factor. This is clearly problematic, as hypertension alone increases your mortality risk and past literature would have called these patients with obesity and hypertension, ‘healthy’. This is likely why most studies have reported that ‘healthy’ obesity is still related with higher mortality risk.
Jennifer Kuk, York University
To truly determine to what extent overweight itself is a risk factor, you have to look at people with overweight who don’t show any of the (other?) risk factors. That’s precisely what the researchers from York did. They followed 54,089 people from five different cohort studies. They categorized them into people with:
- Overweight without other metabolic risk factors
- Overweight and other metabolic risk factors
- Only elevated blood sugar, blood pressure, or lipids
- Elevated blood sugar, blood pressure, or lipids combined with obesity or one of the other metabolic risk factors
The researchers tried to make as much distinction as possible between the effects of the separate factors and different combinations.
The results showed that elevated lipids (fats), blood pressure, and blood sugar alone were sufficient to increase the risk of death. However, this wasn’t the case for overweight.
Healthy overweight exists, but is quite rare
The researchers from York therefore conclude precisely the opposite of their British counterparts a year earlier.
“This means that hundreds of thousands of people in North America alone with metabolically healthy obesity will be told to lose weight when it’s questionable how much benefit they’ll actually receive.”
‘Thousands’ sounds like a lot of ‘healthy obese’ people, but that’s because there are a lot of overweight people. In their study, it turned out that only one in twenty obese people had none of the other risk factors. So, if you have (severe) overweight, it’s wise to assume that there are other risk factors present. At least, that’s what you should bet on.
For doctors, this could mean that they shouldn’t assume that losing weight will improve everyone’s condition. At least not in terms of medical complaints. Losing severe overweight can certainly improve quality of life. However, that may not be your top priority when you come to your doctor with severe complaints. We already knew from earlier research that doctors sometimes wrongly attribute weight as the cause of complaints. So, it seems wise for a doctor to check the various relevant values that may or may not be associated with overweight. Not necessarily to prevent ‘unnecessary weight loss’, but mainly not to expect it to be an unjustified remedy for the complaints.
Who are those healthy obese people?
Finally, I’d like to know more about those people with a lot of overweight without the usual associated problems.
For example, do we see that BMI gave a wrong impression and the body fat percentage was relatively low (like in bodybuilders and powerlifters for example)? Or was the fat mass distributed in a favorable way? For example, waist circumference wasn’t considered as in last year’s study.
What does the diet and activity look like? Are they very active people who eat a lot, or very inactive people who eat a little too much every day (I would think the former).
Useful to know if you want to change unhealthy overweight into healthy overweight. If such a thing exists.
References
- J. L. Kuk, M. Rotondi, X. Sui, S. N. Blair, C. I. Ardern. Individuals with obesity but no other metabolic risk factors are not at significantly elevated all-cause mortality risk in men and women. Clinical Obesity, 2018;
- https://onlinelibrary.wiley.com/doi/full/10.1111/cob.12263
