The decision: an older adult already has sarcopenic obesity (SO — coexisting excess fat and age-related low muscle mass/strength/function) and is deciding whether resistance training (RT) alone, without a prescribed diet or weight-loss program, is worth doing — and for which outcome. Polo-Ferrero 2025 is a gold-tier SR-MA (11 RCTs met inclusion; 9 pooled; 513 subjects) answering exactly this: RT versus no treatment / no exercise, no caloric restriction in either arm. (inferred from Polo-Ferrero et al., 2025)
This is the sibling of Resistance Training During Caloric Restriction (Sardeli) but a different decision — see the parameter table below; the two are not in tension and must not be read as one estimate.
Population and design
- Who: older adults meeting an operational SO definition — obesity (BF% > 30% or BMI > 30 kg/m²) and sarcopenia (SMI ≤ 7.76 kg/m², gait speed ≤ 1 m/s, or hand grip ≤ 21 kg). Mean age 68 ± 5.94; the studies «primarily focused on women with SO», one included both sexes. SO «affect[s] approximately 11% of older adults globally».
- Exposure: RT, «typically over a 12-week period» (one 10-week), three sessions per week (one twice
weekly). No dietary / caloric-restriction co-intervention — searched:
caloric restriction/weight loss/energy restrictionreturn zero across both source chunks. - Comparator: no treatment / without exercise (not diet, not another modality).
- Quality: PEDro overall good (1 fair, 7 good, 3 excellent). GRADE moderate-to-very-low by outcome.
What RT does — three outcomes, three verdicts
Body composition — small benefit, GRADE moderate (the best-graded of the three outcomes). Pooled across SMI, ASM, BF%, BMI, BMD (7 studies): «favorable effects on body composition … (standardized mean difference [SMD] = 0.35, 95% confidence interval [CI] = 0.12; 0.57, p = 0.003, n = 324)», heterogeneity I² = 0%. Funnel asymmetry flags possible publication bias. «Moderate-quality evidence supports improvements in body composition (SMD = 0.35; 95% CI: 0.12, 0.57).»
Physical performance — small benefit, GRADE low. 4 studies: «positive effects on physical performance in older individuals with sarcopenia and obesity compared to those without exercise, demonstrating a low effect size (SMD = 0.36; 95% CI = 0.03; 0.69; p = 0.003; n = 155)», I² = 0%. The only significant performance subgroup was single-leg stance (SLS): «SMD = 0.88; 95% CI = 0.09; 1.68; p = 0.03; n = 29» — a wide interval on 29 people, so a fragile, hypothesis-generating signal, not a reliable magnitude.
Blood biomarkers — null, GRADE low/very-low. 3 studies (LDL, HDL, TG, CRP): «no significant differences in biomarker concentrations between older individuals with SO undergoing exercise programs compared to those without exercise (SMD = 0.1; 95% CI = −0.28; 0.49; p = 0.6; n = 111)». A 12-week RT program did not move the lipid/inflammatory panel in this pool — insufficient evidence rather than proof of no effect (small n, short horizon; authors note baseline inflammation/insulin status may modify response).
The benefit is fat-loss-weighted, not demonstrated muscle gain
(Polo-Ferrero et al., 2025) The composite body-composition SMD is carried by fat, not by shown muscle accretion. The only significant body-composition subgroup was BF%: «exercise interventions led to a significant reduction in BF% among older individuals with sarcopenia and obesity when compared to those without exercise (SMD = 0.52, 95% CI = 0.19; 0.86, p = 0.002, n = 150)». The muscle-mass subgroups (SMI, ASM) did not reach significance. The authors state the nuance plainly: «While RT is known to enhance lean mass [29], some studies, similar to our own, have reported reductions in BF% without a corresponding increase in muscle mass [67–69]», and «one trial found that RT did not significantly increase muscle mass in older adults with SO, but led to improvements in physical function».
Decision consequence. In the SO stratum, the realistic near-term RT return is lower body fat and better function, not bigger muscles. That inverts the naive RT builds muscle expectation for this population — a refinement, not a contradiction, of Protein and Resistance Training for Muscle and Strength (where muscle/strength gains are shown in leaner or diagnosed-sarcopenic — but not specifically sarcopenic-obese — pools).
Surrogate-to-outcome transmission (the open loop)
(inferred from Polo-Ferrero et al., 2025) Every endpoint here is a surrogate: BF%, SMI, SMD body-composition and performance-test scores, not falls, disability, independence, or mortality. The patient-important link is asserted, not measured in this MA: the authors argue «even modest improvements in these variables can significantly reduce the risk of disability and falls in older adults», and that balance/postural gains matter «for fall prevention». Treat function (SLS, gait, chair-stand) as the closer-to-patient target and BF%/muscle indices as the farther surrogate -> Surrogate Outcomes. The loop stays open: no endpoint here is a realized patient outcome.
Distinction from Sardeli (RT during caloric restriction) — not a tension
This page resolves the open thread left on Resistance Training During Caloric Restriction
([AWAITS] now struck). The two MAs answer different questions on every axis; the parameter table is
the evidence, built before the prose (no cell, no claim):
| Parameter | Sardeli — RT During Caloric Restriction | Polo-Ferrero — RT for Sarcopenic Obesity | Same quantity? |
|---|---|---|---|
| Population | obese elderly (mean > 57 y) undergoing a weight-loss diet; not required to be sarcopenic | sarcopenic obesity (coexisting low muscle + excess fat; mean 68, mostly women); not dieting | NO |
| Exposure | RT added to caloric restriction (RT during an energy deficit) | RT alone, 12 wk, 3×/wk; no dietary co-intervention | NO |
| Comparator | caloric restriction alone (CR without RT) | no treatment / no exercise (no deficit in either arm) | NO |
| Outcome | lean-body-mass retention during weight loss — absolute RMD in kg; % of CR-induced LBM loss prevented | composite body-composition SMD (SMI/ASM/BF%/BMI/BMD pooled); performance SMD; biomarker SMD | NO (retention fraction vs standardized composite) |
| Effect | ~93.5% of CR-induced LBM loss prevented; RMD 0.819 kg [0.364–1.273], p < 0.001 | body-comp SMD 0.35 [0.12, 0.57]; performance 0.36 [0.03, 0.69]; biomarkers null | NO |
(inferred from Polo-Ferrero et al., 2025; Sardeli et al., 2018)
Not-joined check (ii) fires decisively — different scope/population/exposure/outcome-unit, consistent
once matched: RT preserves muscle a diet would otherwise strip, during a deficit (Sardeli) and RT
lowers fat and improves function in sarcopenic-obese people who are not dieting (Polo-Ferrero) are both
true and do not clash. So this is a distinction, not a [[tension]] and not type-E (different claim,
not the same claim by independent routes; author lists are also fully disjoint).
The ~50% referent was mis-attributed. Sardeli’s open thread contrasted its 93.5% against «50% LBM loss attenuation when different types of exercise were added to CR in sarcopenic obese individuals», reading the gap as evidence RT is the active modality. That ~50% figure is from Sardeli’s own cited ref [10] — a different, mixed-modality MA of exercise added to CR — not from Polo-Ferrero. Polo-Ferrero reports no lean-mass-retention-under-deficit fraction at all (it has no deficit), so it cannot confirm or refute the 93.5%-vs-50% comparison. That comparison remains Sardeli’s unresolved internal contrast with an un-held source -> named gap:.
Decision relevance
(inferred from Polo-Ferrero et al., 2025)
- For an older adult with sarcopenic obesity, resistance training is worth doing — mainly for fat and function, modestly, on moderate-to-low evidence. Expect a small composite body-composition gain (SMD 0.35) driven by lower body fat (BF% SMD 0.52) and a small function gain (SMD 0.36), over ~12 weeks at 3×/week. Do not expect it to normalize lipids or inflammation (null biomarker panel), and do not promise muscle growth — the muscle-mass signal was not significant here.
- RT over aerobic in this stratum — author-asserted, not head-to-head here. The authors conclude RT «has been shown to be superior to aerobic exercise in terms of functionality and body composition in adults with SO», citing other work; this MA did not itself compare modalities (RT vs no-treatment only). Hold it as a directional lead, not a within-MA finding -> Exercise Modality for Body Composition in Obesity.
- Safety is in RT’s favour. RT was «generally safe», with only minor exercise-typical effects (muscle soreness) in two trials — relevant given the deconditioned, higher-injury-risk SO population.
- Pairs the diet lever, does not replace it. The authors note a «low-calorie, high-protein diet has been shown to reduce BF% in older adults with SO, while supplementation has not». RT here is the no-deficit lever; the diet-plus-RT combination (and RT-during-deficit for muscle retention) is the Sardeli / Protein Intake During Energy Restriction question.
Limits
(inferred from Polo-Ferrero et al., 2025)
- Surrogates only; open loop at the patient level (above).
- Short and small. 9 pooled RCTs, 12-week horizon, n in the low hundreds per outcome (n = 29 for the only significant performance subgroup). Durability and long-term function/mortality are unstudied here.
- Mostly women — transportability to older men with SO is a stated gap.
- SO definition is not yet unified — Polo-Ferrero applies one operational criterion («recent expert
recommendations»); «clinical data on SO are still insufficient to support a unified definition» — the
same
type-Ggap flagged on Sarcopenia Definition and Diagnosis. - Publication-bias signal on body composition and biomarkers (funnel asymmetry).