Morning fasting upregulates insulin signalling in adipose tissue
Skipping breakfast may contribute to better insulin signalling, according to a recent study, which shows that expression of the IRS2 gene, involved in insulin signalling, is upregulated in both lean and obese individuals following a 6-week morning fasting programme.
The research team performed a randomized controlled trial on 29 healthy lean (mean age 36±11 years; 64 percent female) and 20 obese (mean age 43±10 years; 65 percent female) individuals, from whom subcutaneous abdominal tissue (SCAT) biopsies were collected at baseline and after 6 weeks of morning fasting or daily breakfast consumption.
In lean individuals, extended morning fasting resulted in significantly upregulated genes involved in lipid turnover (ACADM gene; p=0.007) and insulin signalling (IRS2 gene; p=0.03) pathways, as opposed to those who had regular breakfasts. There were no significant impacts on other genes, including those involved in inflammation and mitochondrial signalling.
In comparison, morning fasting did not significantly affect the expression of the ACADM gene in obese individuals (p>0.1). Only the expression of the IRS2 gene was significantly upregulated following the 6-week fasting programme (p=0.049). Other genes involved in insulin signalling, and which were proximal to IRS2 in the pathway, were likewise unaffected by fasting.
According to researchers, the present findings indicate that changes in adipose tissue glucose control, as a result of morning fasting, are most probably due to proteins involved in signalling.
“Finally, lower insulin-stimulated SCAT glucose uptake rates in obese individuals are proportional to whole-body fat mass, suggesting a compensatory downregulation, presumably to prevent excessive de novo lipogenesis in adipose tissue,” they added.