The acute effects of time-of-day-dependent high fat feeding on whole body metabolic flexibility in mice

Abstract

Background: Both circadian disruption and timing of feeding have important roles in the development of metabolic disease. Despite growing acceptance that the timing of food consumption has long-term impact on metabolic homeostasis, little is known regarding the immediate influence on whole body metabolism, or the mechanisms involved. We aimed to examine the acute effects of time-of-day-dependent high fat feeding on whole body substrate metabolism and metabolic plasticity, and to determine the potential contribution of the adipocyte circadian clock.

Methods: Mice were fed a regimen of 4-h meal at the beginning and end of the dark (waking) cycle, separated by 4 h of fasting. Daily experimental conditions consisted of either an early very high fat or high fat (EVHF or EHF, 60 or 45% kcals from fat, respectively) or late (LVHF or LHF) meal, paired with a low fat (LF, 10% kcals from fat) meal. Metabolic parameters, glucose tolerance, body fat composition and weight were assessed. To determine the role of the adipocyte circadian clock, an aP2-CLOCK mutant (ACM) mouse model was used.

Results: Mice in the EVHF or EHF groups showed a 13.2 or 8.84 higher percentage of caloric intake from fat and had a 0.013 or 0.026 lower daily average respiratory exchange ratio, respectively, compared with mice eating the opposite feeding regime. Changes in glucose tolerance, body fat composition and weight were not significant at the end of the 9-day restricted feeding period. ACM mice did not exhibit different metabolic responses to the feeding regimes compared with wild-type littermates. Circadian clock disruption did not influence the short-term response to timed feeding.

Conclusions: Both the total fat composition of diet and the timing of fat intake may differentially mediate the effect of timed feeding on substrate metabolism, but may not induce acute changes in metabolic flexibility.

Figure 1

Sample size of the study under a Feeding × Genotype factorial design (a) and feeding regimes for timed feeding (b). In (b), mice were either fed (A) HF diet (45% calories from fat) during the first 4 h, followed by control diet (10% calories from fat) during the last 4 h of the active phase (EHF), (B) VHF diet (60% calories from fat) during the first 4 h, followed by VHF diet during the last 4 h of the active phase (EVHF), (C) Control diet during the first 4 h, followed by HF diet during the last 4 h of the active phase (EVHF) or (D) Control diet during the first 4 h, followed by VHF diet during the last 4 h of the active phase (LVHF). Diets were matched for protein content (20% calories from protein).

Figure 2

Mice fed a HF or a VHF diet were divided into two distinct feeding groups, as depicted in Figure 1. The effects of these feeding regimes on caloric intake, divided by zeitgeber hour (a and e), average daily calorie intake (kcal day⁻¹; b and f), average percent daily intake of fat (c and g) and average percent daily intake of carbohydrate (d and h) were determined. Data are shown as mean±s.e.m. (n=11 EHF, n=11 LHF, n=12 EVHF and n=13 LVHF). *P<0.05 **P<0.01 ***P<0.001.

Figure 3

The effects of distinct feeding regimes on respiratory quotient. Changes in RER throughout baseline and restricted timed feeding (a and d). Average daily values of RER (b and e). Average values of RER by 4-h zeitgeber interval (c and f). Data are shown as mean±s.e.m. (n=11 EHF, n=11 LHF, n=12 EVHF and n=13 LVHF). ^#The main effect of feeding regimes on RER during the inactive/light phase. **P<0.01, ***P<0.001.

Figure 4

The effects of distinct feeding regimes, divided by 4-h zeitgeber interval, on daily energy expenditure (a and b) and physical activity (e and f) for EHF vs LHF. The effects of distinct feeding regimes, divided by 4-h zeitgeber interval, on daily energy expenditure (c and d) and physical activity (g and h) for EVHF vs LVHF. Data are shown as mean±s.e.m. (n=11 EHF, n=11 LHF, n=12 EVHF and n=13 LVHF). *P<0.05, **P<0.01.

Figure 5

The effects of distinct feeding regimes on percent body fat and body mass. Average values of percent body fat (a and c). A change in body weight between baseline and post-experiment (b and d). Data are shown as mean±s.e.m. (n=11 EHF, n=11 LHF, n=12 EVHF and n=13 LVHF).

Figure 6

The effects of distinct feeding regimes on glucose tolerance for EHF vs LHF (a) and EVHF vs LVHF (b). Plasma glucose levels were measured at 15, 30, 60, 90 and 120 min after intraperitoneal injection of 10% d-glucose (0.01 ml g⁻¹). Data are shown as mean±s.e.m. (n=11 EHF, n=11 LHF, n=12 EVHF and n=13 LVHF).