Is healthy obesity a thing?

Obesity is one of the biggest (puns intended) economic burdens in the world, estimated to be about $2 trillion or 2.8% of the global gross domestic product in 2014. The prevalence of obesity has doubled in 73 countries since 1980 and has shown a continuous increase in most others.

In the U.S., annual healthcare costs are $147–210 billion, with another $4.3 billion due to job absenteeism, and another $506 per obese worker for reduced productivity. Obese adults spend 42% more on direct healthcare costs than normal-weight adults.

On an individual level, obesity is associated with an increased risk for having 18 co-morbid diseases, including type II diabetes, cardiovascular disease, and cancer. Globally, obesity accounts for roughly 5% of deaths from any cause.

MHO co-morbidities

Overall, obesity seems to be a drain on health and the wallet. But does that mean this applies to every obese person? Can someone be obese and healthy?


Metabolically healthy obesity

Although there is no consensus on what criteria define metabolic health, some obese people are considered to have “metabolically healthy obesity” (MHO). Commonly, these people would be obese but not have insulin resistance, elevated blood lipids, or high levels of visceral fat.

But, this is temporary — a grace period to get your shit together before things get worse.

Stefan MHO

Roughly 50% of people with MHO will develop at least one metabolic abnormality within 3–10 years, compared to about 25% of healthy normal-weight folk. Moreover, the risk of developing metabolic syndrome increases with both the severity and duration of obesity.

For those individuals who maintain their MHO classification, there isn’t much protection from developing the diseases that afflict their unhealthy obese counterparts. Having MHO is associated with an increased risk for adverse cardiovascular events (e.g., heart attacks), subclinical atherosclerosis (i.e., plaque buildup that is not severe enough to present with symptoms), nonalcoholic fatty liver diseasekidney function decline, and type II diabetes.

Sure, the risk is less than that of unhealthy obesity, but it is still there compared to being healthy and of normal weight.



The personal fat threshold

I believe the MHO phenotype represents a transient state where people have yet to cross their personal fat threshold, which is different for everyone based on genetics, lifestyle, and environmental factors.

The concept of the personal fat threshold was put forth by Roy Taylor and Rury Holman, from Newcastle University, in their 2015 publicationNormal weight individuals who develop type 2 diabetes: the personal fat threshold.

Essentially, fat gain is a protective mechanism resulting from a chronic energy surplus. Having too much energy in the blood stream (e.g., glucose and fat) is harmful, and fat cells beneath the skin (subcutaneous fat) suck this stuff up to protect us. As the fat cells take in more energy, they expand in size, like a balloon filling with air.

But balloons can hold only so much before they pop, and a dead fat cell is of no help to anyone. So, once the fat cell reaches its threshold, it shuts itself off from the energy supply to preserve its own life. Thankfully, we have many fat cells that can pick up the slack of those that are no longer filling up with energy.

Jung PFT for MHO

How many fat cells depends on you. The more you have, the more obese you can become before metabolic abnormalities occur. This is why some obese people are metabolically healthy, while others are not. Similarly, this explains the unfortunate few who develop type II diabetes even at a normal body weight. Their body weight may be “normal”, but they are carrying too much fat for their personal fat threshold.

Once most of our fat cells are full, we see the development of insulin resistance (one of the ways they stop taking in more energy) and the accumulation of glucose (diabetes) and fat (dyslipidemia) in the blood. We also see emergency backup systems come into play, whereby the body inappropriately stores this excess energy in organs, especially the liver and pancreas. This is known as visceral fat.

Goossens MHO


Summing up

There is no such thing as “healthy” obesity. Sure, you can be obese and free of metabolic abnormalities, but you still have a markedly increased risk of developing obesity-related diseases in comparison with normal weight individuals.

Not only are your ever-expanding fat cells giving out more and more stress signals as they fill up, providing a beautiful setting of low-grade, chronic inflammation, but if things don’t change, you’re going to pass your personal fat threshold at some point. Hello diabetes, fatty liver, and heart disease!

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