Weight gain

Category: General & Whole-Body Symptoms · All general symptoms

What it can feel like

Weight gain means your body weight gradually increases over weeks to months. Some of it is fat gain from eating and activity patterns, but weight can also rise because of fluid collecting in the body, hormonal changes or medicines — which is why the pattern matters.

Possible causes

A symptom can have many causes, and most are not serious. The lists below group conditions this symptom can be associated with — common causes first. They are possibilities to discuss with a clinician, not a diagnosis.

Common causes

Weight gain can be associated with eating and activity changes, poor sleep, stress, giving up smoking, and medicines such as some steroids, antidepressants and diabetes treatments. It also commonly happens around the menopause.

Other possible causes

Weight gain can be associated with an underactive thyroid, with hormone conditions such as polycystic ovary syndrome or Cushing's syndrome, and with fluid retention from heart, kidney or liver problems — especially when the gain is rapid and comes with swollen ankles or breathlessness.

Red flags — when to seek help promptly

Rapid weight gain over days with swollen legs and breathlessness
Weight gain with a puffy face, severe tiredness and feeling cold all the time
Weight gain together with reduced urine output
A child whose growth pattern changes suddenly

What a clinician may do

A clinician will weigh and measure you, ask about diet, activity, sleep, mood and medicines, and examine for signs of fluid or thyroid problems. Blood tests for thyroid function, sugar and kidney function are common, and treatment depends on the cause found.

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Frequently asked questions

How can I tell fat gain from fluid gain?

Fluid gain is usually quicker — days rather than months — and often shows as tight shoes, swollen ankles that pit when pressed, and breathlessness lying flat. Fat gain is slower and more evenly spread. Either pattern can be assessed by your clinician.

Can medicines cause weight gain?

Yes — several commonly used medicines can, including some steroids, antidepressants, epilepsy medicines and insulin. Never stop a prescribed medicine because of weight gain; discuss it with your clinician, who may be able to adjust it.

Related symptoms — General & Whole-Body Symptoms

Chills Excessive sweating Excessive thirst Fatigue Feeling cold all the time Feeling generally unwell (malaise)

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Please note: This page is educational information about a symptom. A symptom alone cannot diagnose any condition, and the causes listed here are possibilities, not a diagnosis. If you are worried about a symptom — especially one that is new, severe, getting worse or not going away — please see your own clinician, who can examine you and arrange tests. In an emergency, call your local emergency number.