Time-restricted eating with or without a low-carbohydrate diet improved myocardial status and thyroid function in individuals with metabolic syndrome: secondary analysis of a randomized clinical trial.

BMC medicine. 2024;22(1):362
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Metabolic syndrome is a cluster of conditions that increase the risk of heart disease, stroke, and diabetes. Recent dietary approaches, such as time-restricted eating (TRE) and low-carbohydrate diets (LCD), have gained attention for their potential health benefits. The primary aim of this study was to assess the impact of time-restricted eating, with or without a low-carbohydrate diet, on myocardial health and thyroid function in individuals diagnosed with metabolic syndrome. This research is a secondary analysis of a randomised clinical trial, focusing on the effects of dietary interventions on cardiovascular and thyroid health. In the clinical trial, 169 individuals were randomly assigned at a 1:1:1 ratio to the LCD group (n=56), TRE group (n=57), or combination group (n=56). Results showed that taken together, LCD, TRE, and their combination all improved functions of the myocardium and thyroid even though the majority were within the reference range at baseline. Furthermore, TRE with or without LCD conferred substantial benefits regarding creatine kinase [myocardial enzyme], thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), and the T3/ T4 ratio. Authors concluded that their findings highlight the importance of dietary patterns in managing metabolic syndrome.

Abstract

BACKGROUND Obesity and metabolic syndrome (MetS) have become urgent worldwide health problems, predisposing patients to unfavorable myocardial status and thyroid dysfunction. Low-carbohydrate diet (LCD) and time-restricted eating (TRE) have been confirmed to be effective methods for weight management and improving MetS, but their effects on the myocardium and thyroid are unclear. METHODS We conducted a secondary analysis in a randomized clinical diet-induced weight-loss trial. Participants (N = 169) diagnosed with MetS were randomized to the LCD group, the 8 h TRE group, or the combination of the LCD and TRE group for 3 months. Myocardial enzymes and thyroid function were tested before and after the intervention. Pearson's or Spearman's correlation was assessed between functions of the myocardium and thyroid and cardiometabolic parameters at baseline. RESULTS A total of 162 participants who began the trial were included in the intention-to-treat (ITT) analysis, and 57 participants who adhered to their assigned protocol were involved in the per-protocol (PP) analysis. Relative to baseline, lactate dehydrogenase, creatine kinase MB, hydroxybutyrate dehydrogenase, and free triiodothyronine (FT3) declined, and free thyroxine (FT4) increased after all 3 interventions (both analyses). Creatine kinase (CK) decreased only in the TRE (- 18 [44] U/L, P < 0.001) and combination (- 22 [64] U/L, P = 0.003) groups (PP analysis). Thyrotropin (- 0.24 [0.83] μIU/mL, P = 0.011) and T3 (- 0.10 ± 0.04 ng/mL, P = 0.011) decreased in the combination group (ITT analysis). T4 (0.82 ± 0.39 μg/dL, P = 0.046), thyroglobulin antibodies (TgAb, 2 [1] %, P = 0.021), and thyroid microsomal antibodies (TMAb, 2 [2] %, P < 0.001) increased, while the T3/T4 ratio (- 0.01 ± 0.01, P = 0.020) decreased only in the TRE group (PP analysis). However, no significant difference between groups was observed in either analysis. At baseline, CK was positively correlated with the visceral fat area. FT3 was positively associated with triglycerides and total cholesterol. FT4 was negatively related to insulin and C-peptide levels. TgAb and TMAb were negatively correlated with the waist-to-hip ratio. CONCLUSIONS TRE with or without LCD confers remarkable metabolic benefits on myocardial status and thyroid function in subjects with MetS. TRIAL REGISTRATION ClinicalTrials.gov, NCT04475822.

Lifestyle medicine

Fundamental Clinical Imbalances : Hormonal ; Structural
Environmental Inputs : Diet ; Nutrients
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Blood

Methodological quality

Jadad score : 3
Allocation concealment : Yes

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