Intermittent Fasting for Twelve Weeks Leads to Increases in Fat Mass and Hyperinsulinemia in Young Female Wistar Rats

Abstract

Fasting is known to cause physiological changes in the endocrine pancreas, including decreased insulin secretion and increased reactive oxygen species (ROS) production. However, there is no consensus about the long-term effects of intermittent fasting (IF), which can involve up to 24 hours of fasting interspersed with normal feeding days. In the present study, we analyzed the effects of alternate-day IF for 12 weeks in a developing and healthy organism. Female 30-day-old Wistar rats were randomly divided into two groups: control, with free access to standard rodent chow; and IF, subjected to 24-hour fasts intercalated with 24-hours of free access to the same chow. Alternate-day IF decreased weight gain and food intake. Surprisingly, IF also elevated plasma insulin concentrations, both at baseline and after glucose administration collected during oGTT. After 12 weeks of dietary intervention, pancreatic islets displayed increased ROS production and apoptosis. Despite their lower body weight, IF animals had increased fat reserves and decreased muscle mass. Taken together, these findings suggest that alternate-day IF promote β -cell dysfunction, especially in developing animals. More long-term research is necessary to define the best IF protocol to reduce side effects.

Reversion to regular diet with alternate day fasting can cure grade-I non-alcoholic fatty liver disease (NAFLD) in high-fructose-intake-associated metabolic syndrome

“…On the contrary, zero-caloric-intermittent fasting with continued fructose intake, herein, was not only able to significantly decrease the overall and visceral obesity parameters in MSF group at the end of the study period versus their matched values at 8th week, but also, it significantly decreased both in MSF group compared to MS group and MSRD group, becoming even significantly lower than controls. These observations agree with Wan et al [52], Yang et al [19], Marinho et al [53], and Munhoz et al [54], and denote that caloric restriction by ADF strongly decreased obesity whether overall or visceral, despite the presence of fructose in diet, exceeding the effect of complete cession of fructose in MSRD group. These observations are consistent with Munhoz et al [54] who found a 35% decrease in total caloric intake and 20.35 % decrease in body weight gain after 12 weeks of ADF in rats.…”

“…These observations agree with Wan et al [52], Yang et al [19], Marinho et al [53], and Munhoz et al [54], and denote that caloric restriction by ADF strongly decreased obesity whether overall or visceral, despite the presence of fructose in diet, exceeding the effect of complete cession of fructose in MSRD group. These observations are consistent with Munhoz et al [54] who found a 35% decrease in total caloric intake and 20.35 % decrease in body weight gain after 12 weeks of ADF in rats.…”

Fasting and refeeding cycles alter subcutaneous white depot growth dynamics and the morphology of brown adipose tissue in female rats

“…Okuno et al (2018), (47) showed that adipose tissue presents healthy expansion, featuring protective properties, and that oxidative stress inhibits this expansion, modifying the tissue architecture and exacerbating inflammation. Studies showed that prolonged IFR caused increased stress and elevated serum corticosterone concentration in rats (48) , as well as increased net ROS production, leading to oxidative imbalance (49) . In our study, although the content of reactive oxygen and corticosterone species were not assessed, hypertrophy was identified in BAT and WAT, as well as fibrosis in BAT, which could be resulted from the increase in the number of reactive oxygen species.…”

Early Cytokine-Induced Transient NOX2 Activity Is ER Stress-Dependent and Impacts β-Cell Function and Survival

“…Batches of 10 similar-sized islets were selected and checked for the insulin secretion assay, as previously described [ 23 , 24 ]. Briefly, islets were incubated in KH buffer with 2.8-mM glucose at 37 °C for 30 min.…”