NEAT and Daily Energy Expenditure in Transitional Years

Published February 2026 | Educational Resource

Understanding Non-Exercise Activity Thermogenesis

Non-Exercise Activity Thermogenesis (NEAT) is the energy expended during all activities outside formal exercise, sleep, and digestion. This includes occupational activities, household tasks, fidgeting, maintaining posture, and spontaneous movement throughout the day.

NEAT comprises approximately 15–30% of total daily energy expenditure in typical adults, making it a substantial contributor to energy balance. For sedentary individuals, NEAT may be particularly important, as it often exceeds energy expenditure from formal exercise.

Measurement of NEAT

NEAT is measured using several approaches:

• Accelerometers: Wearable devices that record movement patterns throughout the day
• Pedometers: Step counters for quantifying daily walking
• Activity questionnaires: Self-reported daily movement and activities
• Indirect calorimetry: Laboratory measurement of energy expenditure during various daily activities

Hormonal Influences on NEAT

Emerging research suggests that hormonal status influences NEAT through multiple mechanisms:

Oestrogen and Physical Activity Patterns

Oestrogen influences central nervous system regulation of activity and motivation. Some studies indicate that women with higher oestrogen levels self-select higher activity levels, while others show reduced spontaneous activity during low-oestrogen phases of the menstrual cycle.

During perimenopause, when oestrogen is declining and erratic, women may experience shifts in spontaneous activity motivation and patterns. However, individual variation is substantial—not all women report activity changes.

Fatigue and NEAT

Perimenopausal women frequently report increased fatigue or reduced energy. This subjective experience may translate to reduced spontaneous movement and activity. Whether this reflects true oestrogen effects on energy metabolism or represents a complex interaction with sleep disruption, mood changes, and other symptoms remains an active area of research.

NEAT Changes During Perimenopause

Research specifically examining NEAT changes during perimenopause is limited compared to studies of basal metabolic rate. However, available evidence suggests:

• Some women report reduced daily movement and activity during perimenopause
• Joint pain and muscle discomfort may reduce NEAT in some individuals
• Sleep disruption may contribute to reduced daytime activity
• Substantial individual variation exists; not all women experience NEAT reduction

Contribution to Overall Energy Expenditure Changes

If NEAT declines during perimenopause, even modestly (e.g., 100–200 kcal/day reduction), this compounds the effects of BMR reduction and contributes to overall energy expenditure decrease. The cumulative effect of 2–8% BMR reduction plus possible NEAT reduction means total daily energy expenditure may decline by 5–10% or more in some women.

NEAT and Body Composition Interactions

NEAT is a modifiable component of energy expenditure. Unlike BMR, which changes primarily through metabolic and hormonal regulation, NEAT can be influenced by behavioural choices. However, both BMR reduction and potential NEAT reduction during perimenopause create a context where maintaining active patterns requires more deliberate effort than in younger years.

Summary

NEAT comprises a substantial portion of daily energy expenditure. Research suggests some women experience reduced NEAT during perimenopause, though individual variation is considerable. This change, combined with BMR reduction, contributes to overall shifts in energy expenditure during the midlife transition.

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