Please do not blame yourself for this — it is one of the most demoralising experiences of perimenopause, and it is a biological shift, not a failure of discipline or willpower.

Here is what is likely happening: as oestrogen declines in perimenopause, the body becomes more metabolically conservative. Muscle mass decreases (muscle burns calories; less muscle means fewer calories burned at rest). The hormonal environment prioritises fat storage, particularly around the abdomen. Sleep disruption raises cortisol, which drives further fat accumulation. All of this is happening at the same time.

Eating less, in this context, can actually make things worse. Severe calorie restriction signals scarcity to the body, which responds by lowering the metabolic rate further, accelerating muscle loss, and holding on to fat stores. This is not a character flaw — it is physiology. Women who eat very little in perimenopause often end up in a cycle where eating less produces less result, which leads to eating even less, with worsening results.

What tends to work better: eating enough to support your muscle (which means enough protein — approximately 1.2–1.6g per kg body weight), doing strength training to maintain and rebuild muscle, managing sleep and stress (both directly affect metabolism and fat distribution), and addressing any underlying medical causes.

Two tests worth asking your doctor for: thyroid function (TSH + fT4) and ferritin (iron stores). Hypothyroidism is common in perimenopause and causes exactly this pattern of weight gain that doesn’t respond to eating less. Iron deficiency causes fatigue that makes exercise harder. Both are very treatable.