What Is NEAT?
Non-Exercise Activity Thermogenesis (NEAT) is the energy expended through daily occupational, leisure, and spontaneous physical activity—everything beyond formal exercise and resting metabolism. This includes fidgeting, postural changes, occupational movement, and general physical activity. NEAT can account for 15–30% of total daily energy expenditure in sedentary individuals and up to 50% in active individuals.
NEAT Suppression During Caloric Restriction
Magnitude of Reduction
Metabolic chamber studies document reductions in NEAT of 20–30% during caloric restriction. This suppression occurs largely unconsciously—individuals move less, fidget less, and maintain postures that require less muscular activity. These changes are not volitional but rather reflect physiological adaptations to energy deficit.
Mechanisms of NEAT Suppression
Leptin-Mediated Pathways: Leptin signalling drives activity and motivational behaviour. During caloric restriction, leptin levels drop sharply, reducing dopaminergic activation and motivation for physical activity. This creates a cascade favouring reduced movement.
Energy Conservation: The body conserves limited energy by reducing costly movement patterns. Postural adjustments favour positions requiring less muscular tension. Fidgeting and spontaneous movement decline.
Central Nervous System Signalling: Alterations in orexin and other neuropeptides involved in arousal and motivation contribute to reduced NEAT.
Persistence Into Refeeding
Importantly, NEAT suppression does not immediately reverse upon refeeding. Even during weight regain phases when energy is abundant, NEAT remains somewhat suppressed relative to baseline. This delayed normalisation of activity expenditure contributes to preferential fat regain, as the additional energy is not offset by increased movement-based energy expenditure.
Cumulative Effects Across Cycles
Repeated cycles of restriction and refeeding appear to produce cumulative effects on NEAT regulation. Individuals with extensive dieting histories may show chronically elevated baseline susceptibility to NEAT suppression, such that even modest dietary restriction triggers substantial activity reduction.
Interaction With Structured Exercise
Caloric restriction typically reduces NEAT independently of changes in structured exercise. However, the combination of caloric deficit and reduced NEAT creates substantial total energy deficit, which can impair exercise performance and recovery. Maintaining NEAT during restriction is metabolically costly and may not be sustainable without adequate nutrition.
Individual Variation
The degree of NEAT suppression varies considerably between individuals. Some people naturally move more and show more pronounced NEAT reductions when restricting, whilst others move less baseline and show modest additional reduction. Occupational activity level, baseline fidgeting tendency, and genetic factors influence individual NEAT response to restriction.
Implications for Weight Management
Because NEAT suppression is largely unconscious and driven by physiological signals rather than conscious control, it can undermine weight loss efforts. Individuals may be unaware of how much less they move during restriction. Strategies to maintain or increase NEAT (structured occupational activity, intentional movement) may partially offset the metabolic efficiency gains from NEAT suppression, but such strategies require conscious effort against physiological drives.