Abstract
Background: Low metabolic flexibility (MetF) may be an underlying factor for metabolic health impairment. Individuals with low MetF are thus expected to have worse metabolic health than subjects with high MetF. Therefore, we aimed to compare metabolic health in individuals with contrasting MetF to an oral glucose tolerance test (OGTT).Methods: In individuals with excess body weight, we measured MetF as the change in respiratory quotient (RQ) from fasting to 1 h after ingestion of a 75-g glucose load (i.e., OGTT). Individuals were then grouped into low and high MetF (Low-MetF n = 12; High-MetF n = 13). The groups had similar body mass index, body fat, sex, age, and maximum oxygen uptake. Metabolic health markers (clinical markers, insulin sensitivity/resistance, abdominal fat, and intrahepatic fat) were compared between groups.Results: Fasting glucose, triglycerides (TG), and high-density lipoprotein (HDL) were similar between groups. So were insulin sensitivity/resistance, visceral, and intrahepatic fat. Nevertheless, High-MetF individuals had higher diastolic blood pressure, a larger drop in TG concentration during the OGTT, and a borderline significant (P = 0.05) higher Subcutaneous Adipose Tissue (SAT). Further, compared to Low-MetF, High-MetF individuals had an about 2-fold steeper slope for the relationship between SAT and fat mass index.Conclusion: Individuals with contrasting MetF to an OGTT had similar metabolic health. Yet High-MetF appears related to enhanced circulating TG clearance and enlarged subcutaneous fat.
Highlights
Metabolic health refers to the state of normal regulation of glucose and lipid metabolism
High-metabolic flexibility (MetF) appears related to enhanced circulating TG clearance and enlarged subcutaneous fat
Overnight fasting respiratory quotient (RQ) was similar in the High-MetF and LowMetF groups (0.82 [0.79–0.84] and 0.81 [0.78–0.83], respectively; P = 0.99) and increased to a different extent after glucose ingestion by design (Figure 1A)
Summary
Metabolic health refers to the state of normal regulation of glucose and lipid metabolism. Impaired metabolic health appears determined by ectopic lipid accumulation and insulin resistance [1,2,3]. Excess body weight is not sufficient to alter metabolic health, and some individuals with obesity maintain a metabolically healthy phenotype [1, 5,6,7]. The capacity to adapt fuel oxidation to fuel availability — i.e., metabolic flexibility (MetF) [8] —has been proposed as an underlying factor of metabolic health [9, 10]. Low metabolic flexibility (MetF) may be an underlying factor for metabolic health impairment. Individuals with low MetF are expected to have worse metabolic health than subjects with high MetF. We aimed to compare metabolic health in individuals with contrasting MetF to an oral glucose tolerance test (OGTT)
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