Understanding Perimenopausal Weight Gain The average woman gains 2โ€“5kg during the perimenopausal transition without changing her diet or activity level. This is not imaginary and it is not simply ageing โ€” it is driven by specific hormonal changes that alter where calories go, how much muscle is retained, and how effectively the body burns fat at rest. The conventional advice (eat less, move more) addresses neither the hormonal mechanisms nor the specific metabolic changes of this transition. Declining oestrogen levels shift fat distribution from the hips and thighs to the abdominal area, โ€ฆ