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Unexplained weight gain: common causes

Most weight gain comes from small daily differences in food and activity. A few medical causes are worth ruling out when it is unexplained.

Common causes

  • 01Eating more than you burn (drinks and snacks add up quickly)
  • 02Low activity or a desk job
  • 03Short sleep, which increases appetite
  • 04Some medicines (such as steroids, some antidepressants and some diabetes medicines)
  • 05Occasionally an underactive thyroid

If your periods are also irregular, PCOS is worth ruling out.

What a doctor may check

A thyroid test if the weight gain is unexplained. Blood sugar if you have other risk factors.

When to see a doctor

See a doctor if you gain weight quickly with swelling of your legs or face, or with breathlessness.

This page is general information, not a diagnosis. Venva's content is written against clinical guidelines and systematic reviews, listed below. See our medical disclaimer.

References

  1. 1.Hypothyroidism. The Lancet, 2017.doi:10.1016/S0140-6736(17)30703-1
  2. 2.Recommendations from the 2023 International Evidence-based Guideline for PCOS. Journal of Clinical Endocrinology & Metabolism, 2023.doi:10.1210/clinem/dgad463

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