Feeding and metabolic consequences of scheduled consumption of large, binge-type meals of high fat diet in the Sprague–Dawley rat

Abstract

Providing rats and mice with access to palatable high fat diets for a short period each day induces the consumption of substantial binge-like meals. Temporal food intake structure (assessed using the TSE PhenoMaster/LabMaster system) and metabolic outcomes (oral glucose tolerance tests [oGTTs], and dark phase glucose and insulin profiles) were examined in Sprague–Dawley rats given access to 60% high fat diet on one of 3 different feeding regimes: ad libitum access (HF), daily 2 h-scheduled access from 6 to 8 h into the dark phase (2 h-HF), and twice daily 1 h-scheduled access from both 1–2 h and 10–11 h into the dark phase (2 × 1 h-HF). Control diet remained available during the scheduled access period. HF rats had the highest caloric intake, body weight gain, body fat mass and plasma insulin. Both schedule-fed groups rapidly adapted their feeding behaviour to scheduled access, showing large meal/bingeing behaviour with 44% or 53% of daily calories consumed from high fat diet during the 2 h or 2 × 1 h scheduled feed(s), respectively. Both schedule-fed groups had an intermediate caloric intake and body fat mass compared to HF and control (CON) groups. Temporal analysis of food intake indicated that schedule-fed rats consumed large binge-type high fat meals without a habitual decrease in preceding intake on control diet, suggesting that a relative hypocaloric state was not responsible or required for driving the binge episode, and substantiating previous indications that binge eating may not be driven by hypothalamic energy balance neuropeptides. In an oGTT, both schedule-fed groups had impaired glucose tolerance with higher glucose and insulin area under the curve, similar to the response in ad libitum HF fed rats, suggesting that palatable feeding schedules represent a potential metabolic threat. Scheduled feeding on high fat diet produces similar metabolic phenotypes to mandatory (no choice) high fat feeding and may be a more realistic platform for mechanistic study of diet-induced obesity.

Large, binge-type meals of high fat diet change feeding behaviour and entrain food anticipatory activity in mice☆

“…Schedule-fed mice showed a large reduction in control diet intake during the early hours of the dark phase and in the hours following the scheduled feed. However, notably, and in line with our previous observations in rats (Bake et al., 2014), schedule-fed mice did not significantly reduce their control diet intake when analysed in 1 h intervals (Fig. 2A,C,F) or change their meal pattern (Fig.…”

“…However, the period immediately before scheduled feeding is characterised by near normal levels of caloric intake from stock diet. We have previously observed the same phenomenon in schedule-fed rats (Bake et al., 2014). The absence of relative negative energy balance, in advance of the initiation of the binge, in either species, is in line with our previous findings (Bake et al., 2013) where there was no evidence of potentially causative perturbation in expression of hypothalamic homeostatic neuropeptide genes prior to consumption of large binge-type meals.…”

“…Despite the limited effect of scheduled feeding on food intake microstructure during the 3 h period prior to HFD access in both mice (current study) and rats (Bake et al., 2014), there were substantial changes in activity pattern in this time frame. The 2 h to 3 h period preceding a daily scheduled meal is regarded as the crucial time frame for FAA (Challet et al., 2009; Mistlberger, 1994; Shibata et al., 2010).…”

“…Consistent with previous reports, when control diet was replaced during scheduled feeding (Bake et al., 2013), mice rapidly adapted their feeding behaviours and binged on the palatable high fat diet (Fig. 1C), exhibiting a larger binge-like meal than rats under the same dietary regime (Bake et al., 2013; Bake, Morgan, & Mercer, 2014). Furthermore, mice showed an increase in body weight (Fig.…”

Differential expression of CART in feeding and reward circuits in binge eating rat model

“…Different schedules of diet presentation for the induction of BE-like condition are reported. Daily [18,33,34] or even alternate day [35,36] access to palatable diet for 2-h has been shown to produce BE in rats. However, it is suggested that development of binging is enhanced and remain stable for longer period when it is offered only 3 times per week than for 2-h each day [19,35].…”