When it's hotter or colder outside on the day someone gives a blood sample, their body's IGF-1 and IGFBP-3 levels tend to change in predictable ways — suggesting that the weather might be one reason these health markers go up and down with the seasons.

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Evidence from Studies

Supporting (1)

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Community contributions welcome

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Serum IGF-1 and IGFBP-3 levels in healthy Korean men aged 19–40 years: a cross-sectional analysis of reference ranges and seasonal variation

Cross-Sectional Study

Human

2025 Sep

This study found that in young Korean men, blood levels of two important growth proteins change with the seasons—higher in some seasons, lower in others—likely because of temperature changes. So yes, the weather outside seems to affect these body markers.

Contradicting (0)

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No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

Serum IGF-1 and IGFBP-3 levels in healthy Korean men aged 19–40 years: a cross-sectional analysis of reference ranges and seasonal variation

Score: 46

DOI: 10.12793/tcp.2025.33.e13

Similar Assertions

In young Korean men, a protein in the blood called IGFBP-3 goes up in the fall and drops in the winter, and it seems to rise when it’s warmer outside — which is the opposite of how another related protein, IGF-1, behaves.

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84%

In young Korean men, the level of a growth-related hormone in the blood tends to be higher during winter and spring than in autumn, and this might be linked to changes in the weather.

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82%