Time-restricted eating affects human adipose tissue fat mobilization

Abstract

Objective: Time-restricted eating (TRE), a dietary approach that confines food intake to specific time windows, has shown metabolic benefits. However, its impact on body weight loss remains inconclusive. The objective of this study was to investigate the influence of early TRE (eTRE) and delayed TRE (dTRE) on fat mobilization using human adipose tissue (AT) cultures.

Methods: Subcutaneous AT was collected from 21 participants with severe obesity. We assessed fat mobilization by measuring glycerol release in AT culture across four treatment conditions: control, eTRE, dTRE, and 24-h fasting.

Results: TRE had a significant impact on lipolysis (glycerol release [mean (SD)] in micromoles per hour per gram: control, 0.05 [0.003]; eTRE, 0.10 [0.006]; dTRE, 0.08 [0.005]; and fasting, 0.17 [0.008]; p < 0.0001). Both eTRE and dTRE increased lipolysis compared with the control group, with eTRE showing higher glycerol mobilization than dTRE during the overall 24-h time window, especially at the nighttime/habitual sleep episode (p < 0.0001). Further analysis of TRE based on fasting duration revealed that, independently of the time window, glycerol release increased with fasting duration (in micromoles per hour per gram: 8 h = 0.08 [0.001]; 12 h = 0.09 [0.008]; and 16 h of fasting = 0.12 [0.011]; p < 0.0001).

Conclusions: This study provides insights into the potential benefits of TRE on fat mobilization and may guide the design of future dietary strategies for weight management and metabolic health.

Figure 1:

Study design. Treatment conditions: Control: simulating a regular dietary pattern with four daily meals and nighttime fasting 8 a.m. and 8 a.m. of the following day; eTRE: early time-restricted eating between 8 a.m. – 12a.m.; dTRE: delay time-restricted eating between 4 p.m. - 8 p.m.; Fasting (F): 24-hour of continuous fasting. All the explants are synchronized between 6 −7 a.m. On day 1, the explants were incubated according to the treatment, and on day two, the same treatment guidelines were maintained while the explants and culture medium are collected every 4 hours. Oranges dotted line means fasting hours, the gray rectangle with the plates alludes to simulated mealtimes, nighttime fasting is represented by a gray rectangle, and the active day by a white rectangle, and blue arrows point to the sampling moment.

Figure 2:

Population average glycerol release every 4 hours during the 24-hour period according to the treatment. Data are represented in black squares for Control, white squares with black borders for Fasting, white circles with black borders for eTRE, and black triangles for dTRE. All standard errors of means are represented as vertical lines. Asterisk (*) and hash (#) indicate statistical significance (P < 0.0001). Asterisk (*) were included when differences were significant between the Control and eTRE in the Circadian Time (CTs) points and hash (#) when differences were significant between Control and dTRE. Control was significantly different at every point compared to the 24-hour continuous Fasting condition (P < 0.0001) For every CT. Furthermore, significant differences were also found between eTRE and Fasting condition at CTs 4, 8, 12, 16, 20, and between dTRE and Fasting condition for CTs 0, 12, 16, 20, 24 (symbols for significance are not represented, to avoid confusion). The X-axes are represented in relative local clock time (h; top X-axes) and circadian time (C.T.; bottom X-axes). On the top X- axis, nighttime fasting is represented with a gray horizontal bar, and active day with a white horizontal bar. Data are presented as mean±SEM. *Indicates statistical significance (P < 0.0001).

Figure 3:

24-hour average glycerol release in different treatment conditions. Control (C) (black bar) n=20; eTRE (dotted bar) n=21; dTRE (stripes bar) n=21; Fasting (F) (grey bar) n=21. Figure 3A. 24-hour Glycerol release is divided in two periods: the daytime/awake period (from 8 a.m. to midnight) (Figure 3B) and the nighttime/sleeping period (from midnight to 8 a.m. of the following day) (Figure 3C). All standard errors of means are represented as vertical lines. Data are presented as mean±SEM. * Indicates statistical significance (P < 0.0001) NS not significant.