Metabolically healthy obesity in a young population assisted by the Family Health Strategy in Brazil

Background

Obesity is increasing in younger populations, and is associated with a high cardiovascular (CV) risk, however, it is not clear whether metabolically healthy obesity (MHO) may have a lower CV risk or if it is just an earlier stage of the disease.

Objective

To evaluate the prevalence and CV risk factors associated with MHO in a young population assisted by a Family Health Care unit in a large urban center in Brazil.

Methods

A cross-sectional population study for CV risk assessment in adults aged 20-50 years old from a FHC unit in Rio de Janeiro. Demographic, anthropometric data and CV risk factors were recorded. All underwent office blood pressure (OBP) measurements, laboratory evaluation (lipid and glycidic profile). Obesity was defined as a BMI ≥ 30 kg/m2 and MHO are those who have less than 3 of the following criteria: hypertension, diabetes, total cholesterol ≥ 200 mg/dL, HDL<40 mg/dL (men) and 50 mg/dL (women), triglycerides>150 mg/dL and increased waist circumference.

Results

A total of 632 individuals were evaluated (60% female; mean age 37 ± 9 years). The prevalence of obesity was 26%, of which 73% were classified as MHO. Obeses are older, with a higher prevalence of physical inactivity (51% vs 41%, p = 0.03), hypertension (44% vs 19%, p < 0.001), dyslipidemia (50% vs 36%, p = 0.002) and diabetes (7% vs 2%, p = 0.001) with higher systolic OBP. MHO compared to unhealthy ones are significantly younger and smoke less. Despite being obese, they have lower BMI (33.6 vs 35.2 kg/m2, p = 0.02) and abdominal circumference (102 vs 110 cm, p = 0.03), with lower diastolic BP.

Conclusions

MHO was more prevalent in this young population and seems to have a lower CV risk, however it is not clear whether these younger and less obese individuals are only at an earlier stage of the disease. Perhaps the CV diseases onset is postponed for a few years. Even so, these individuals should not be excluded from public health policies as a form of primary prevention.

Key messages

In this young population, MHO was more prevalent and presented a lower CV risk. The follow-up of MHO will show if they are really healthy or if they are at an early stage of the disease.

Variational studies and replica symmetry breaking in the generalization problem of the binary perceptron

We analyze the average performance of a general class of learning algorithms for the nondeterministic polynomial time complete problem of rule extraction by a binary perceptron. The examples are generated by a rule implemented by a teacher network of similar architecture. A variational approach is used in trying to identify the potential energy that leads to the largest generalization in the thermodynamic limit. We restrict our search to algorithms that always satisfy the binary constraints. A replica symmetric ansatz leads to a learning algorithm which presents a phase transition in violation of an information theoretical bound. Stability analysis shows that this is due to a failure of the replica symmetric ansatz and the first step of replica symmetry breaking (RSB) is studied. The variational method does not determine a unique potential but it allows construction of a class with a unique minimum within each first order valley. Members of this class improve on the performance of Gibbs algorithm but fail to reach the Bayesian limit in the low generalization phase. They even fail to reach the performance of the best binary, an optimal clipping of the barycenter of version space. We find a trade-off between a good low performance and early onset of perfect generalization. Although the RSB may be locally stable we discuss the possibility that it fails to be the correct saddle point globally.