Research

Hormonal

Obesity is associated with impaired immune function, including higher incidence and severity of infectious illnesses and poor antibody responses to vaccines.

If you are obese, your immune system may not function as efficiently as that of a lean person, particularly in responding to vaccines and fighting infections. This is largely driven by hormonal factors like leptin. Maintaining a healthy weight and managing metabolic health are important for supporting robust immune defense.

GoodSupportsHIGH confidence
In general terms, clinical and epidemiological data support the evidence that the incidence and severity of specific types of infectious illnesses are higher in obese persons as compared to lean individuals together with the occurrence of poor anti-body responses to antigens in overweight subjects.
Amelia Martí et al. · Obesity Reviews · 2001

Why this rating

The claim is supported by multiple clinical, epidemiological, and animal studies cited in the review, though the review itself notes some controversy and heterogeneity in human data.

Source

Obesity and immune function relationships

Amelia Martí et al. · Obesity Reviews · 2001

DOI 10.1046/j.1467-789x.2001.00025.x

narrative_reviewCited 422×
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DOI resolved against Crossref · corpus check 2026-06-10

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