A randomized dietary trial evaluating human metabolic responses to energy deficit has revealed stark molecular contrasts between adults who lose substantial weight and those who experience minimal weight loss under the same nutritional protocol. In an exploratory transcriptomic investigation, researchers analyzed peripheral blood mononuclear cells isolated from individuals classified as hyper-responders and hypo-responders following a structured four-week caloric restriction program. The investigation sought to characterize the functional gene expression architecture that distinguishes individuals who respond robustly to energy restriction from those demonstrating pronounced resistance to weight loss. By examining transcriptomic alterations at a stringent statistical threshold, the research team identified widespread differential gene activity between the two intervention groups, establishing that significant physiological divergence in body mass reduction is accompanied by specific, quantifiable shifts in cellular transcription.

Caloric restriction remains the most established and effective non-pharmacological strategy for human weight management, yet clinical interventions consistently reveal substantial inter-individual variability in weight reduction outcomes. In nutritional intervention research, subjects undergoing identical dietary restrictions are routinely categorized based on their physiological response into hyper-responders, normo-responders, or hypo-responders. Within standardized clinical frameworks, hyper-responders are generally defined as individuals who achieve a loss greater than five percent of their baseline body weight, whereas hypo-responders fail to reach this benchmark, losing less than five percent over the intervention timeframe. Although multiple dietary modifications involving macronutrient ratios, functional foods, and hypocaloric regimens have been evaluated, the precise biological and transcriptomic mechanisms driving variable weight loss responses under identical energy deficits have remained unresolved across previous nutritional studies.

Earlier systematic literature reviews conducted on peripheral blood mononuclear cell transcriptomes across hyper- and hypo-responders noted that previously published trials failed to pinpoint specific, universally shared genes or uniform biological pathways across cohorts. Those earlier evaluations observed heterogeneous pathway involvement, noting alterations in cytoplasmic ribosomal protein pathways and transcription initiation sequences across separate studies. Researchers attributed this lack of convergence to pronounced study heterogeneity, including diverse cohort demographics spanning adolescents, premenopausal women, and bariatric patients, along with divergent caloric deficits ranging from twenty to sixty-five percent and substantial differences in dietary macronutrient distributions.

To minimize confounding variables and capture clear transcriptomic separation, the investigators drew participant samples from the NUTRIRES2 clinical trial, a randomized, controlled, double-blind study conducted at the Centro de Biotecnología Genómica within the Instituto Politécnico Nacional in Reynosa, Tamaulipas, Mexico. The broader clinical protocol involved twenty-nine adult volunteers evaluated for changes in anthropometric dimensions, serum lipids, and atherogenic indices during a controlled dietary regimen featuring varied fatty acid compositions paired with caloric restriction. From the twenty-seven participants completing the trial, the authors selected an extreme phenotype sampling cohort consisting of twelve adult volunteers, comprising six hyper-responders and six hypo-responders. This sampling methodology balanced group sizes while maximizing statistical power and isolating biological mechanisms at the extreme ends of the clinical weight loss spectrum.

The twelve selected participants represented young and middle-aged adults with an overall mean age of 37.5 years, balanced evenly with three men and three women in each clinical response cohort. Prior to initiating the dietary phase, baseline anthropometric parameters, age distributions, and sex ratios showed no statistically significant differences between the hyper-responder and hypo-responder groups. Both groups began the trial with identical clinical distributions consisting of two overweight individuals and four individuals with obesity. Over the four-week experimental intervention, every participant received a seven-day rotating menu providing an average twenty percent caloric deficit relative to their calculated basal metabolic rate. Calorie targets were determined using standardized sedentary daily energy calculations, and participants were instructed to restrict moderate or intense physical activities to prevent extraneous energy expenditure.

Following the completion of the four-week dietary deficit, physical assessments confirmed that both participant groups achieved measurable reductions across all evaluated anthropometric indicators, but with pronounced magnitude differences between groups. Hyper-responders exhibited dramatic comparative advantages, achieving 82.3 percent greater weight loss, an 81.5 percent greater reduction in body mass index, a 68.9 percent greater reduction in hip circumference, and a 47.97 percent greater reduction in waist circumference relative to hypo-responders. Consequently, while the diagnostic ratio remained unchanged in the hypo-responder group with four individuals retaining obesity status, the hyper-responder cohort shifted substantially, such that four volunteers transitioned to overweight status and only two remained categorized with obesity, confirming the physiological validity of the extreme responder groups.

Venous blood samples were collected into tubes containing dipotassium ethylenediaminetetraacetic acid following an overnight fast of at least twelve hours at baseline and following the four-week dietary period. RNA integrity was verified through 1.2 percent agarose gel electrophoresis with guanidinium thiocyanate, and fluorometric assays were utilized to determine total concentration. Twenty-four whole-transcriptome sequencing libraries were constructed using ribosomal RNA depletion methods with stranded ligation protocols and sequenced on a MiSeq platform. Quality filtration, trimming, genomic alignment, and read quantification were conducted using FastQC, Trimmomatic, STAR, and featureCounts on the Galaxy public analytical platform.

Bioinformatic differential expression analysis was performed using linear modeling through voom and limma within the Degust environment, applying a false discovery rate threshold of 0.03 or less without arbitrary fold-change cutoffs to restrict false discovery rates. To isolate transcriptomic alterations specifically induced by the caloric intervention, genes exhibiting baseline differential expression prior to dietary intervention were systematically subtracted from post-intervention analyses. In total, 1,581 genes displayed statistically significant differential expression between hyper-responders and hypo-responders. Strikingly, 1,580 of these differentially expressed genes demonstrated downward expression in the hypo-responder group, while exactly one single gene throughout the entire analyzed transcriptome—G1 to S Phase Transition 1, designated as GSPT1—exhibited significant upregulation among hypo-responders.

Among the downregulated transcriptomic profile in hypo-responders, 141 genes exhibited marked suppression characterized by a log2 fold change of at least two, with a subgroup mean log2 fold change of minus 2.19, while the remaining 1,440 downregulated transcripts showed moderate suppression averaging a minus 1.61 log2 fold change. Protein-protein interaction network analysis conducted through the STRING database identified two interrelated functional pathways displaying significant collective enrichment at a false discovery rate of 0.0041: Collagen Chain Trimerization and Collagen Biosynthesis and Modifying Enzymes. Functional enrichment categorized under Gene Ontology terms also identified extracellular matrix structural constituent conferring tensile strength as a significantly enriched molecular function, underscoring systemic suppression of structural extracellular matrix processing in hypo-responding individuals.

While GSPT1 overexpression has previously been documented in human malignancies such as gastric, breast, and liver cancers, the authors noted that in non-malignant metabolic contexts, its elevated expression likely reflects heightened cellular stress, abnormal proliferation, and chronic low-grade inflammation. In individuals with obesity, adipocyte hypertrophy causes cellular mechanical stress, triggering apoptosis, macrophage infiltration, and heightened proinflammatory signaling. The elevated transcription of GSPT1 in hypo-responders may therefore serve as a circulating marker of metabolic stress and inflammatory activation that resists normal metabolic adaptation during caloric deficit.

Downregulated genes within the enriched collagen pathways included critical structural components and enzymatic regulators such as PLOD1, TLL2, and multiple collagen subunits including COL5A3, COL6A5, COL14A1, COL4A1, and COL4A5. Meanwhile, structural collagen genes and the metalloprotease TLL2 regulate fibrillogenesis, basement membrane assembly, and matrix remodeling. When these enzymatic and structural genes are downregulated, extracellular matrix plasticity is compromised, creating a rigid, fibrotic microenvironment that impairs adipocyte adaptation, impedes healthy tissue remodeling, and reinforces systemic insulin resistance during weight loss interventions.

An additional 1,564 differentially expressed genes falling outside the primary collagen interaction network were evaluated through the g:Profiler functional enrichment platform, mapping to molecular activities including general protein binding, microfilament motor activity, phosphorus-transferring transferase activity, and protein kinase activity. These secondary associations indicate that disrupted intracellular signaling cascades, impaired cytoskeletal restructuring, and altered phosphorylation pathways further contribute to the blunted weight reduction seen in hypo-responders. The authors highlighted that while peripheral blood mononuclear cells offer a valuable surrogate tissue reflecting immune and inflammatory alterations, they do not directly represent primary metabolic adipose depots, warranting cautious interpretation and necessitating expanded clinical cohorts to validate these transcriptomic biomarker networks.

Subject of Research: Transcriptomic differences in peripheral blood mononuclear cells between hyper and hypo weight-loss responders

Article Title: Transcriptomic analysis in peripheral blood mononuclear cells from hyper and hypo weight-loss responders

Article References: Vela-Vásquez, D. A., Delgado-Enciso, I., & Sifuentes-Rincón, A. M. (2025). Transcriptomic analysis in peripheral blood mononuclear cells from hyper and hypo weight-loss responders. Genes & Nutrition, 20(1), Article 20. https://doi.org/10.1186/s12263-025-00783-8

Image Credits: AI Generated

DOI: 10.1186/s12263-025-00783-8

Keywords: Transcriptomics, Caloric Restriction, Weight Loss, Gene Expression, PBMCs, GSPT1, Extracellular Matrix, Collagen Biosynthesis, Transcriptomic, analysis, peripheral, blood