Obesity may not lead to serious health consequences for many years. In a study published in JAMA Network Open, the scientists described how such metabolically healthy obesity can be recognized. » />
Obesity is a risk factor for premature death, diabetes, and cardiovascular diseases. However, this rule does not always work. In a minority of cases, obesity does not lead to serious consequences. This phenomenon is called metabolically healthy obesity (MHO).
The diagnostic criterion for obesity is a body mass index (BMI) above 30. To get BMI, you need to divide body weight in kilograms by the square of height in meters.
Scientists still have not agreed on clear criteria under which obesity can be called metabolically healthy. Previously, it was proposed to consider it as such if the metabolic syndrome or tissue resistance to insulin did not develop against its background. However, large studies have shown that in obese people without metabolic syndrome, the risk of death from all causes and from heart disease may remain elevated (higher than in people with normal weight). That is, it is far from always possible to call such obesity healthy. Other formulations, for example, taking into account the coverage of the waist, also did not receive universal acceptance.
Insulin resistance is a condition in which the response of tissues to this hormone becomes weaker. As a result, less glucose enters the cells, and the pancreas begins to produce more insulin to compensate for the violation. This condition is a risk factor for diabetes.
Metabolic syndrome is diagnosed if a person has at least three of the following symptoms:
- high blood sugar;
- low blood «good» cholesterol;
- high blood triglycerides;
- large waist circumference or apple-shaped figure;
- high blood pressure pressure.
Each of the above factors is dangerous in itself. When they are paired together, the risk of cardiovascular disease increases dramatically.
Redefining metabolically healthy obesity
A group of German scientists has developed an alternative approach to the definition of MLO. They analyzed data from more than 380 thousand people taken from two databases: the British Biobank and the large NHANES study (it was devoted to the connection between nutrition and health). The average age of the participants was 41-56 years.
The authors conclude that metabolically healthy obesity meets the following criteria:
- systolic (upper) blood pressure – no higher than 130 millimeters of mercury without the use of antihypertensive drugs;
- waist to hip ratio — no more than 0.95 for women and 1.3 for men;
- no type 2 diabetes.
Participants in a study with MHO that met these criteria had an 8-14 year follow-up risk of death from cardiovascular disease and all causes were almost at the same level as in non-obese people.
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The authors found that the level of «bad cholesterol» and other blood lipids, contrary to expectations, did not have a significant influence on the risk of death in study participants with obesity. Therefore, this indicator was not included in the definition of MLO.
The scientists pointed out that their definition of MLO could only apply to people with a BMI of less than 40. People who are severely obese have an increased risk of death, regardless of other criteria.
Why the new MLO criterion may be more accurate
In an editorial published in the JAMA Network Open, scientists from the Medical College of Alberta Einstein developed the idea of the authors of the study. They pointed out that body mass index is not always a reliable criterion for determining health risks. In addition to this, it is often assessed whether a person has central (abdominal) obesity. Most often, this is used as an indicator of waist coverage. However, a more sensitive diagnostic method is to assess the ratio of waist coverage to hip coverage. It, the authors of the article point out, most accurately predicts the risk of cardiovascular disease.
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