Effects of exercise interventions on leptin and ghrelin levels in middle-aged and older adults with overweight or obesity: a systematic review and meta-analysis.
Zhuangzhuang Guo, Wei Guo, Yimeng Gu et al.
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In 30 seconds
This systematic review and meta-analysis assessed randomized controlled trials of exercise interventions in middle-aged and older adults with overweight or obesity, examining changes in leptin and ghrelin. Across 21 trials, exercise was associated with lower leptin than control conditions (18 comparisons; SMD = -0.32, 95% CI [-0.47 to -0.18], P < 0.0001) and higher ghrelin (nine comparisons; SMD = 0.45, 95% CI [0.11-0.79], P = 0.01). The leptin result was relatively consistent; the ghrelin estimate was less certain because it involved fewer comparisons and substantial heterogeneity.
Key findings
- Leptin was lower with exercise than control across 18 comparisons (SMD = -0.32, 95% CI [-0.47 to -0.18], P < 0.0001; I 2 = 22%).
- Ghrelin was higher with exercise across nine comparisons (SMD = 0.45, 95% CI [0.11-0.79], P = 0.01; I 2 = 74%).
- Subgroup analyses were exploratory; sensitivity analyses supported the stability of the main estimates.
Why it matters
The findings suggest exercise is associated with changes in two hormones involved in energy balance in adults with overweight or obesity in middle and later life. However, the review does not establish that these hormone changes translate into meaningful clinical outcomes. The more heterogeneous ghrelin result and exploratory subgroup findings underscore the need to interpret hormonal responses cautiously.
What to keep in mind
The ghrelin estimate was based on fewer comparisons and had substantial heterogeneity. The authors also note the need for more standardized exercise protocols, clearer dietary control, and consistent hormone measurement.