NEAT is a complex and highly multifaceted variable which contributes to daily energy expenditure.
For some individuals, it contributes enormously. Think farmers, postman and personal trainer. These individuals are standing, moving and generally being more physical overall. For others who are more sedentary and work seated, NEAT levels will be vastly lower. Think Uber drivers, and most office workers.
Importantly, your NEAT levels will change over time as your circumstances do. This is due to evolving environmental factors in particular, such as a job change or even a seasonal shift. If you opt to swap your job as a farmer to become a computer programmer, your NEAT levels will typically plummet. Furthermore, as the seasons change, our daily activities can evolve as well. For instance, you may be more active in summer when the months are warmer, playing more sport and incorporating more outdoor activity. Even other factors such as your location and degree of urbanisation can impact. This all adds up and contributes to energy output.
Likewise, your age will also impact NEAT as well, with NEAT falling as you age. For instance, think about all the sport and activity you likely used to do in your youth, compared to you now in your adult years. Your sex can impact NEAT as well, with traditional roles playing a role here.
Crucially, the caloric environment matters too. That is, if you are imposing yourself to an under or overfeeding environment (calorie deficit or surplus), NEAT levels will change. This is very much an innate compensatory mechanism and will vary from person to person. For instance, some people have a more efficient metabolism in regard to energy expenditure and others more inefficient. This has profound implications on weight management as illustrated by the overfeeding study below by Levine et (1999).
Here NEAT levels varied enormously, and they were the principal player impacting fat gain resistance. Remember, all movement counts, and some people simply fidget and twitch a whole lot more than others, especially with overfeeding scenarios. This is important to factor in when assessing your calorie needs and tolerance potential.
Continuing on with the topic of movement, walking definitely contributes to energy output. This can be a deliberate and conscious decision such as going for a walk to hit your step target, or alternatively it can be subconscious. This difference between conscious and subconscious is helpful and can allow us to sub-categorise further. For instance, a deliberate attempt to hit your step target could be classified as NEPA (non-exercise physical activity). Subconscious step accumulation or general ambulation is different due to the intent of its acquisition. It could also fall into its own sub-categorisation of NENAT (non-exercise non-activity thermogenesis).
Finally, there are elements of NEAT you can control and others you can’t (genetic). Studies on identical twins during under and over feeding illustrate this and suggest genes play a crucial in body weight regulation variability.
Loeffeholz & Birkenfeld (2018). “The Role of Non-exercise Activity Thermogenesis in Human Obesity”.
Bouchard et al (1990). “Sources of Human Psychological Differences: The Minnesota Study of Twins Reared Apart”
Hainer et al (2001). “A Twin Study of Weight Loss and Metabolic Efficiency”
Levine, Eberhardt & Jensen (1999). “Role of non-exercise activity thermogenesis in resistance to fat gain in humans”.