Obese, but metabolically healthy: Is weight loss detrimental? (Series Pt 4/5)

After introducing the concept of the metabolically healthy obese phenotype earlier this week, we have covered the risk of chronic disease as well as mortality among this large proportion of obese individuals who despite their excess weight remain metabolically healthy. Today we look at the effect of weight loss among such individuals.

While countless epidemiological studies have shown that as you move from a normal weight (BMI = 18.5-24.9 kg/m2) towards overweight (BMI = 25-29.9kg/m2) and obesity (BMI ≥ 30kg/m2) the risk of many diseases increases exponentially, it is also true that approximately 25% of obese individuals ­are metabolically healthy despite their excess weight. These individuals are also at no greater risk of chronic diseases such as diabetes and cardiovascular disease than their lean counterparts. However, as we learned yesterday, despite being metabolically-healthy obese individuals may still be at greater risk of mortality.

This latter point would indicate that despite suggestions to the contrary, all obese individuals, regardless of their metabolic status should be counseled to lose some weight.

But should they? What if weight-loss among otherwise healthy obese individuals actually makes them unhealthy?

According to a paradoxical study by Karelis and colleagues, otherwise healthy obese women who lose weight via dieting may actually WORSEN their metabolic profile.

In the study, a sample of obese women were divided into either metabolically healthy (20 women) or metabolically at-risk (24 women) based on their level of insulin sensitivity (a marker of diabetes risk – the more insulin sensitive, the better) as measured using the euglycemic-hyperinsulinemic clamp procedure. These women then underwent 6 months of a medically supervised dietary weight loss program consisting of approximately 500-800 calorie reduction in daily food intake.

After the intervention all women lost a significant amount of body weight (approximately 6-7%).

More interestingly, however, while the metabolically at-risk obese women showed a 26% increase in their level of insulin sensitivity, the insulin sensitivity of the metabolically healthy obese women actually deteriorated by 13%!

In other words, by losing weight those obese women who were originally metabolically healthy may have actually increased their risk of diabetes.

This finding is very unexpected, and as of yet has not been corroborated by another study. Nevertheless, it does raise the very intriguing possibility that weight-loss among otherwise healthy obese women may not only unnecessary but, in fact, counter-productive.

This finding falls broadly in line with a recommendation paper by Drs. Arya Sharma and Robert Kushner published in the International Journal of Obesity earlier this year. In that paper the authors proposed a novel obesity classification system which not only assesses weight, but also health complications of excess weight. Germane to the above discussion, Sharma and Kushner recommend that among obese individuals who have “no apparent obesity-related risk-factors” the goal of patient management should be to simply avoid further weight gain, or maintain current weight, rather than to induce weight loss. (To read Dr. Sharma’s full discussion of the new classification system please visit his blog here.)

In essence, the idea that healthy obese individuals may not have much to benefit from weight loss, metabolically speaking, is not that surprising – they are healthy to begin with! However, whether weight-loss may actually be ill-advised for healthy obese individuals needs to be investigated by future studies – until a counter-intuitive finding such as this one is corroborated, many remain doubtful (including me). For example, it remains unknown whether exercise-induced weight loss among healthy obese individuals could also result in metabolic detriment (doubtful). Additionally, we have currently no idea if the above finding also holds true among men.

No idea, until tomorrow, that is.

Tune in tomorrow to read about a study I did during my PhD work in an attempt to resolve this issue.


References and Further Reading:

Karelis, A., Messier, V., Brochu, M., & Rabasa-Lhoret, R. (2008). Metabolically healthy but obese women: effect of an energy-restricted diet Diabetologia, 51 (9),

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9 Responses to Obese, but metabolically healthy: Is weight loss detrimental? (Series Pt 4/5)

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  2. Actually, Peter, the only thing that study suggests is that losing weight by forced caloric restriction may be detrimental. One possible mechanism for this is the effect of caloric restriction on cortisol levels. As cortisol levels go up, insulin sensitivity declines.

    This study suggests nothing at all, however, about the benefit of losing weight using a paleo or low-carb diet that doesn’t restrict calories.

  3. Hi Chris,

    While I am certainly intrigued by your hypothesis, I’m not sure it is supported by the results of the study. If what you propose is true – weight loss via caloric restriction driving up cortisol which the would reduce insulin sensitivity – how would you explain the increase in the same variable in the other group undergoing the exact same treatment?

    Perhaps more importantly, I’m a bit perplexed as to how one might lose weight via a paleo, low-carb or other fad diet without restricting calories. I’d love to consider any peer-reviewed studies you have come across to suggest the contrary.

  4. Mary says:

    There is some evidence that it can be possible to lose weight by switching to lower energy density choices (ie. switching to having half a plate of vegetables at dinner, decreasing drinks with calories etc) rather than calorie counting and aiming for a specific calorie limit, ie a prescribed “diet”. The majority of people with excess weight wish to decrease their weight, as one of the other posters suggested this is related to social stigma etc, and they are looking for support from their health professionals. Slowing and then stopping weight gain are always the first goals, but if someone were to achieve that and wanted to keep working on weight loss, it does not seem ethical for a health professional to recommend that they should only focus on maintaining their weight and to not provide further support.

  5. Pingback: Obese, but Metabolically Healthy: Is Weight Loss Beneficial? (Series Pt 5/5) | Obesity Panacea

  6. LKL says:

    I’m curious what the rate of weight loss was, in terms of lbs per week vs. percent of total weight over 6 months. There’s a pretty big difference between 3 lbs/week and 1 lb/week in terms of how much one’s body protests at the end of the day, and it would not be surprising to me if the difficulty level of the former was associated with some (short-term?) negative effects.

  7. rps says:

    I’ve heard of low carb dieters becoming more insulin resistant too. The idea is that your cells don’t want to take up glucose because they’re sparing it for the brain. But that has nothing to do with diabetes, because your blood sugar won’t spike if you’re not eating carbs in the first place. It’s not diabetes if your blood sugar never goes up. It’s a different mechanism and a different phenomenon than insulin resistance in somebody who’s eating more carbs. This might be the same thing that’s going on with formerly obese weight losers.

    What happens to their A1C and their fasting plasma glucose (not OGTT because their bodies are no longer adapted to dumping boatloads of glucose into cells anymore)?

  8. My tip: Fried foods, especially deep-fried, contain a great deal of fat. While chicken meat and fish are usually leaner than beef or pork, they can contain more fat when they are fried. Take a look at how the number of grams of fat in a chicken breast can change depending on how it is cooked.

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