The obesity paradox: understanding metabolically healthy obesity

While obesity is often a red flag for potential health problems, not everyone with excess weight experiences these issues. Some people are considered "metabolically healthy obese" (MHO). 

What defines metabolically healthy obesity?

MHO refers to people who don't have the usual health problems linked with obesity, like high blood pressure or insulin resistance. Even though their BMI is high, their blood pressure, cholesterol, and insulin resistance are normal.¹ This shows that obesity doesn't impact everyone the same way.

Despite the intriguing nature of MHO, there's still some debate about what exactly qualifies someone as MHO. One study pointed out that there's no agreed-upon standard, and that factors like smaller waist size, better fitness levels, lower insulin resistance, and fewer metabolic risk factors are important.¹

Additionally, another study found that over 30 different definitions have been used in research, often looking at metabolic syndrome components or measuring insulin resistance.² 

The impact of lifestyle on metabolic health

To support metabolic health, it's important to exercise regularly and eat a diet rich in whole, unprocessed foods. Research indicates that lifestyle changes can have a positive impact on metabolic health, even for those classified as metabolically healthy but obese.² 

Some studies show that lifestyle factors like how much you eat or exercise aren't significantly different between those who have metabolically healthy obesity (MHO) and those with metabolically unhealthy obesity (MUO), but it's important to consider the influence of genetics. This may help explain the variations in metabolic health between these two groups.³

Challenging perceptions of health and obesity

Social perceptions often unfairly equate obesity with poor health, leading to stigma and bias. However, the concept of MHO reveals that health cannot be judged solely by appearance or weight. Individuals with MHO show that it’s possible to carry excess weight while maintaining healthy metabolic markers.¹ 

This challenges the idea that obesity always means poor health and shows why health checks should look at a range of factors, not just BMI. This approach helps fight stigma and encourages a broader understanding of health, beyond just labelling people as "obese" or "not obese."

Considering the risks and limitations

Even though MHO might seem less risky at first, it's not a permanent condition and can turn into MUO over time. One study mentioned that things like getting older or being less active can increase this risk.³ Long-term research suggests that 30% to 50% of those with MHO could become MUO in 4-20 years, especially if there's a drop in insulin sensitivity or weight gain.³

Additionally, the health risks for those with MHO are still significant. They have a lower chance of developing type 2 diabetes and heart disease compared to MUO, but their risk is still higher than people who are both lean and metabolically healthy.³ This highlights why it's important for MHO individuals to keep an eye on their health and stick to a healthy lifestyle.

The numan take

The concept of MHO shows that not all excess weight equates to a health crisis. But this isn’t a free pass. Holding on to metabolic health necessitates an ongoing commitment to a healthy lifestyle filled with active choices and nutritious eating.

References

1. Blüher, M. (2020). Metabolically Healthy Obesity. Endocrine Reviews, 41(3), bnaa004. https://doi.org/10.1210/endrev/bnaa004

2. Stefan, N., Häring, H., Hu, F.B., & Schulze, M.B. (2013). Metabolically healthy obesity: Epidemiology, mechanisms, and clinical implications. The Lancet Diabetes & Endocrinology, 1(2), 152-162. https://doi.org/10.1016/S2213-8587(13)70062-7

3. Smith, G. I., Mittendorfer, B., & Klein, S. (2019). Metabolically healthy obesity: facts and fantasies. Journal of Clinical Investigation, 129(10), 3978–3989. https://doi.org/10.1172/JCI129186