Many women in their 40s and 50s worry that progesterone might cause weight gain — especially when symptoms like bloating, fatigue or abdominal fat increase during perimenopause.

The truth is more nuanced: most of these changes are driven by the hormonal and metabolic changes, not by progesterone. And importantly, not all progesterone types behave the same way in the body.

Below is a clear, evidence-based summary designed for women seeking clarity.

Types of progesterone and their effects

1. Micronised (bio-identical) progesterone

This is the most physiologically aligned form and the preferred option for hormone therapy in perimenopause (sequential regimens) and post-menopause (continuous regimens).

• Sequential regimen = progesterone taken for part of the month alongside oestrogen.
• Continuous regimen = progesterone taken every day with oestrogen.

Main actions:

• Protects endometrial tissue.
• Calming effect on the brain via GABA-A receptors — often improving sleep quality and reducing anxiety.

Does it cause weight gain?

 No evidence shows weight gain with micronised progesterone.

Some women experience transient dizziness or bloating during the first days due to differences in absorption and metabolism.

To understand why some women tolerate it better than others, you can read more here:

2. Synthetic progestins — group with androgenic activity

Example: levonorgestrel (found in intrauterine systems such as Mirena and similar devices worldwide).

When it is used:

• Heavy or irregular bleeding

• Endometrial protection for women using systemic oestrogen during menopause hormone therapy

• Contraception during perimenopause
• Management of polyps or endometrial thickening.

Positive effects:

• Very strong endometrial protection
• Reduces bleeding over time

Possible downsides:

• Androgenic activity may cause acne, mild hair changes or mood changes in a small % of women
• Some women may not tolerate the irregular bleeding in the first 3–6 months.

3.Synthetic progestins — anti-androgenic group

Example: Drospirenone (found in certain combined pills).

When it is used:

• Premenstrual syndrome or PMDD (Premenstrual Dysphoric Disorder)
• Premenstrual fluid retention and bloating
• Acne or androgen-related skin issues

Positive effects:

• Mild diuretic action
• Anti-androgenic effect (beneficial for skin and hair)
• Helps regulate premenstrual mood and fluid retention

Possible downsides:

• A small number of women may experience breast tenderness or mild nausea initially.

• Clinical studies have not shown consistent weight gain with drospirenone when used at standard doses, although individual responses can vary.

4.Dienogest

Used in treatment of endometriosis.

Positive effects:

• Reduces inflammation and pelvic pain
• Shrinks endometriosis lesions (reduces the size and activity of endometrial implants)

• Improves bleeding patterns — periods often become lighter, less painful, and may become infrequent over time.

Possible downsides:

• Spotting, mild headaches, or breast tenderness
• Appetite changes in a minority of women, but no consistent weight gain in studies

Why weight gain happens in midlife

Weight gain after 40 is driven by hormonal and metabolic changes that occur rapidly during the menopause transition — not by progesterone

Key mechanisms supported by evidence:

• ↓ Oestrogen ⇒ ↓ basal metabolic rate
• ↓ Lipid oxidation and ↑ visceral fat storage
• ↑ Insulin resistance when lean mass decreases
• Redistribution of fat to the abdomen (“centralisation”)

If visceral fat or metabolic changes are your main concern, you can explore my medically supervised healthy weight programmes here:

Should I test my progesterone levels?

A common question — but progesterone’s effects cannot be predicted by a simple blood test. 

They depend on several biological factors:

• Pharmacokinetics: how your body absorbs and metabolises progesterone.

• Pharmacodynamics: how sensitive your progesterone receptors are (how strongly your cells respond).

• Pharmacogenetics: your genetic variations that influence both absorption and receptor response.

Because of this, progesterone levels fluctuate and rarely predict how you will feel.

Most women in perimenopause and menopause do not benefit from routine progesterone testing.

A full clinical assessment is more reliable and clinically meaningful

For a detailed explanation of why symptoms matter more than test numbers, you can read this guide:

And if you would like personalised guidance, you can book a consultation here:

Conclusion

Progesterone — especially micronised natural progesterone — does not cause weight gain.

Weight and body composition changes in midlife are mainly driven by hormonal and metabolic changes, not by hormonal therapy.

Choosing the right type of progesterone depends on your symptoms, your metabolic profile, and your personal medical history — and with the right approach, most women feel significantly better.