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

Intermittent food restriction (IFR) is used mainly for weight loss, however, its effects on adipose tissue are not known when alternating with obesogenic diet. To demonstrate its effects on morphological dynamics of fat deposits, female Wistar were distributed into the groups: standard control (ST-C), with commercial diet; DIO control (DIO-C), with a diet that induces obesity (DIO) during the first and last 15 days, replaced by a standard diet for 30 intermediate days; standard restricted (ST-R), with standard diet during the first and last 15 days, with six cycles of IFR at 50% of ST-C; and DIO restricted (DIO-R), in DIO during the first and last 15 days, with six cycles of IFR at 50% of DIO-C. At 105 days of life, white adipose tissue (WAT) and brown adipose tissue (BAT) deposits were collected, weighed and histology performed. IFR groups showed higher food intake (DIO-R: 670.8±31.86kcal/g vs DIO-C: 606.5±26.23kcal/g, p<0.0001), energy efficiency (DIO-R: 3.80±0.15 g/kcal vs DIO-C: 3.26±0.17 g/kcal, p<0.0001), WAT (DIO-R: 5.65±0.30g/100g, ST-R: 3.64±0.23g/100g vs. DIO-C: 4.56±0.30g/100g, ST-C: 2.87±0.31g/100g, p<0.0001) and BAT (DIO-R: 0.13±0.004g/100g vs DIO-C: 0.13±0.005g/100g, p<0.0001) than its respective controls. Furthermore, IFR groups presented hypertrophy of WAT and BAT, as well as fibrosis in BAT. Thus, IFR can establish prospective resistance to weight loss by favoring changes in adipose tissue morphology, increased energy intake, and efficiency. Finally, the DIO diet before and after IFR aggravates the damages caused by the restriction.