Everyone knows a calorie deficit is the key to weight loss - burn more than you eat. For those of us keeping track, it sounds simple: just aim to consume X calories per day and stay below that number.
By the HCG Health DeskPublished 4 min read
A cargo bike and a teen riding a bike in a pilot bus-bike lane in Mexico City. Photo: Fabián Heredia Montiel / Wikimedia Commons (CC BY 4.0)What this article covers
Everyone knows a calorie deficit is the key to weight loss - burn more than you eat. For those of us keeping track, it sounds simple: just aim to consume X calories per day and stay below that number. Math should take care of the rest, coming in right below your maintenance level. That's the plan, anyway. But reality looks different.
The missing factor is non-exercise activity thermogenesis (NEAT): the calories burned all day long, for motions outside of exercise. NEAT is the term for the difference between total daily energy expenditure and the calories officially spent in exercise and rest. His famous 600 miles of walking per year later, Levine's theory is widely accepted: a person's energy expected to be burned on paper is a lot more variable than it seems up front.
Why NEAT Matters
NEAT counts your steps, of course, but it also includes the cumulative calorie cost of tapping a pen, playing with a phone, gesturing while you talk, and paper shuffling. NEAT is also the energy you burn while on conference calls, working, studying, and running errands, though those can also have workout equivalents. The official definition is more restrictive: "the energy expended for everything that is not sleeping, eating, or sports-like exercise."
For instance, according to the Mayo Clinic, fidgeting from your seated position boosts energy dissipated by about 54% compared with sitting still. Walking around the room while on the phone can compound that effect. Add up these invisible activities and you approach a sense of the real inner workings of NEAT. Levine's NEAT bucket can contribute 100 to 800 calories to your total daily expenditure, giving you a sense of how NEAT might be underestimated in the average weight loss plan.
But that's before considering the effect of dieting, which can make a person's maintenance calories seem to shift underfoot, almost by themselves. Indeed, NEAT is reportedly quite sensitive to energy levels - but how much NEAT decreases, and why, is starting to come into focus.
The Hidden Drop During Dieting
The active ingredient in that NEAT decrease is called adaptive thermogenesis. Levi Watkins and eight colleagues published a textbook definition in a new NCAA Bookshelf chapter: "Adaptive thermogenesis includes changes in BMR (basal metabolic rate), EAT (thermic effect of food), and NEAT that are modulated by factors including increased or decreased caloric intake, nutrient supply, and changes in hormone levels."
The implications are important: your maintenance calories upon slimming down may never go back up fully, even with changes in other variables. The review reached a specific estimate for one of those NEAT drops: "A review in the NCBI Bookshelf states that NEAT refers to spontaneous physical activity that is not specially the result of voluntary exercise." The review found reductions averaging 150 calories per day, or 27%. Undercut by those converted calories, what felt like maintenance calories evaporates - making you sit up and take notice of your unusual NEAT.
But that's not the only research to catch the phenomenon so plainly. A more-recent NCBI review also echoes the point: decreases in REE, EAT, and NEAT can arise from a negative energy balance due to restriction and/or exercise. In an intervention of overweight men, Watkins and his team also found a decrease of 116 calories per day.
The rains are falling - but does this conclusion hold up for any given healthy adult? Or does it mean that NEAT drops differ from person to person?
Why the Same Person Can Burn Very Different Calories on Different Days
A review hosted by Kent State University gives one answer: NEAT is the most variable portion of total daily energy expenditure - by far. But if such a big shift in NEAT can happen, why don't you feel it voice a difference in your own body each day? Some studies suggest healthy adults may experience NEAT reductions greater than 50 calories per day, which they don't necessarily notice.
The numbers are close but not exact: one human balances temperature differently than another. That may be due to genetics, genes, or environmental factors. One study found a 43% increase in NEAT just from standing up. Indeed, the standing desk may be one way to watch your calories over time.
What to Do?
What you should do is to be aware that NEAT is part of the equation; it can be measured but is hard to observe. Diets do reduce NEAT, but exercise exerts a bigger effect on your metabolism. For people with unlimited time and energy, he recommends interventions like meetings that take place while walking. You might also introduce movement breaks and keep track of steps, but the little things add up. If you're planning a motivational desk shake, you might be surprised. Levine found that one shake used 50 more calories than sitting still.
The Bottom Line
NEAT is the key to why diets seem to fail: they change your body's resting equilibrium, and your maintenance calories go down. You may feel like you're cheated - but in truth, your body is responding by conserving its precious energy.
Perhaps you're still hoping you can outsmart your body in future, but this episode of the NEAT story at least suggests it's harder than that.
This is health information, not medical advice. We describe mechanisms, numbers and published evidence. What applies to you depends on your history, your medication and your clinician — take decisions with them, not with an article.
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HCG Health Desk
HCG is written by an independent desk covering weight loss, diets and metabolic health. We do not sell programmes, supplements or injections, and we say when the evidence is thin.
