In obese adults, reducing calorie intake is linked to changes in specific microRNA levels in fat tissue, which are associated with increased breakdown of fats and the formation of new fat cells.
Mechanism
Synthesis from 1 study
When you eat fewer calories, your fat cells change how their genes are read by loosening the packaging around energy-burning genes and turning down certain tiny RNA molecules that block fat breakdown. At the same time, they turn up another RNA that helps mitochondria burn fat more efficiently....
Most probable mechanism
When the body gets fewer calories, it senses the energy drop and changes how genes are read in fat cells. This causes certain tiny RNA molecules to decrease, which removes brakes on fat-burning and fat-cell maturation, while another RNA increases to boost energy production in mitochondria. At the same time, the physical packaging of DNA in fat cells loosens around key metabolic genes, making them easier to turn on. Together, these changes help fat cells burn more fat, become smaller and healthier, and improve how the body uses energy.
Reduced energy intake lowers cellular ATP levels, increasing the AMP:ATP ratio and activating AMPK, which in turn elevates NAD+ levels to stimulate SIRT1 deacetylase activity.
AMPK and SIRT1 activation, along with reduced mTOR signaling, coordinate changes in epigenetic regulators that alter DNA methylation, histone modifications, and microRNA expression in adipose tissue.
DNA hypomethylation occurs at promoters of metabolic genes such as PPARG, LEP, and IRS1, increasing their accessibility for transcription and enhancing lipid oxidation and mitochondrial biogenesis.
Histone marks shift toward activation: H3K4me3 and H3K9ac increase at metabolic gene loci, while H3K27me3 decreases, creating a permissive chromatin environment for transcription of genes involved in lipid mobilization and insulin sensitivity.
MicroRNA expression is reprogrammed: miR-27a and miR-34a are downregulated, relieving repression of target mRNAs that promote lipid catabolism and adipocyte differentiation, while miR-193b is upregulated to enhance mitochondrial fatty acid oxidation.
Combined epigenetic and post-transcriptional changes increase expression of genes driving lipid breakdown, mitochondrial function, and adipocyte remodeling, leading to improved metabolic flexibility and reduced ectopic lipid accumulation.
Evidence from Studies
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