Why "Eat Less, Move More" Breaks Down (Even When You Do It Right)

This is part 3 of a series on why weight loss stalls in perimenopause even when you're doing everything "right." In part 1, we covered the biology of perimenopause and menopause. In part 2, we broke down why the calories you track aren't always the calories you actually absorb. This time, we're tackling the other half of the equation: calories out, and why your body doesn't just sit still while you diet. (please add links)

If part 2 was about what's coming in, this one's about what's going out, and why that number moves around a lot more than most people realize.

Calories Out Has 4 Moving Parts, Not Just 1

"Calories out" gets treated like a fixed number you can look up and trust. Many people use TDEE calculators and expect if they consume less than they’re burning they’ll lose weight. It’s not quite that simple because “calories out” is actually made up of four separate systems:

1. Resting energy expenditure (REE): what your body burns just existing

2. The thermic effect of food (TEF): the energy it costs to digest what you eat

3. NEAT (non-exercise activity thermogenesis): all the small, spontaneous movement that isn't planned exercise: fidgeting, standing, pacing, taking the stairs without thinking about it

4. Planned exercise: the intentional workouts

Every one of these can shift based on what and how you eat, what your body composition is, and other factors–and that's before your body even starts adapting to a diet.

The Thermic Effect of Food: Not All Calories Cost the Same to Digest

Here's something most tracking apps never account for: protein has the highest thermic effect of any macronutrient. Digesting it burns roughly 20-30% of its own calories, which means a gram of protein listed as 4 calories often nets closer to 3 calories once your body pays the digestion cost. Crazy, right? 

It's not just about protein versus carbs and fat either. It's about how processed the food is. In one controlled study, researchers had participants eat calorie-matched, macro-matched sandwiches, one made with whole grain bread and cheddar cheese, the other with white bread and processed cheese product. Same calories. Same protein, carbs, and fat breakdown. The only difference was how processed the ingredients were.

The whole food meal burned 19.9% of its calories through digestion. The processed meal burned only 10.7%, almost half as much. Same calorie count on paper, a real difference in what your body actually did with it.

NEAT: The Movement You Don't Even Notice You're Doing (or Not Doing)

This is the part of "calories out" that explains why two people can eat the exact same surplus and have wildly different results.

In a classic controlled study, researchers overfed 16 healthy volunteers by 1,000 calories a day for 8 weeks. Some participants barely gained fat. Others gained substantially more, even though everyone ate the identical surplus. The difference came down to NEAT. About two-thirds of the extra energy expenditure that offset the surplus came from non-exercise movement, not structured workouts, just more fidgeting, more standing, more incidental movement throughout the day. Changes in NEAT explained a 10-fold difference in fat storage between participants.

Here's the part that matters for dieting, not just overfeeding: NEAT works in reverse too. The more weight someone has lost, the more their NEAT tends to decrease, often without them noticing. On days someone exercises formally, NEAT can also quietly drop, so a hard workout doesn't always add up to more total movement for the day, it can just shift where the movement comes from.

Are you Thrifty or Spendthrift? Some Bodies Just Adapt Differently

Not everyone's calories-out system responds to a deficit or surplus the same way. Researchers describe two general patterns:

Spendthrift bodies have a smaller drop in energy expenditure during a deficit, and a bigger increase in energy expenditure during overfeeding. These bodies are more forgiving in both directions.

Thrifty bodies do the opposite. A bigger drop in expenditure during a deficit, and a smaller increase during a surplus. These bodies hold onto energy more tightly no matter which direction you push them.

Neither is a character flaw. It's physiology. But it explains why two clients doing the exact same plan can see genuinely different results, and why "just eat less" hits some bodies harder than others.

Adaptive Thermogenesis: Your Body Pushes Back After Meaningful Weight Loss

Once someone loses roughly 10% of their body weight, metabolic rate tends to drop by more than body composition changes alone would predict. A smaller body costs less energy to move and maintain, that part is expected. Adaptive thermogenesis is the extra drop on top of that, your body actively resisting further loss, not just adjusting to a smaller frame.

This is one of the most useful things to know if you hit a stall after meaningful progress. It's not always a sign that something's going wrong. It can be a sign that the body has reached a point where a structured diet break, a planned period of eating for maintenance and not loss may genuinely help before continuing.

So What Do You Actually Do With This?

Stop treating "calories out" as one fixed, predictable number. It's four separate systems, and three of them (TEF, NEAT, and adaptive thermogenesis) shift based on what you eat, how much you've already lost, and how your individual body responds to change.

Stop assuming a stall means you did something wrong. Sometimes it means NEAT has quietly dropped, or the body has crossed into adaptive thermogenesis territory after real progress, both of which are normal, predictable, and manageable with the right adjustments.

Start recognizing that some bodies are simply thriftier than others, and that's not a failure of discipline. It's a reason to adjust the approach, not the effort.

This is exactly why coaching isn't just "eat less, move more" repeated indefinitely. I help clients recognize when a stall is a signal to adjust, not a signal to push harder, and build a plan around how their specific body actually responds. 

Tired of hitting a wall that "try harder" can't explain? Let's figure out what your body is actually doing.  Book a free discovery call and let's build a plan around your real physiology, not a generic calorie math problem.

Sources & Further Reading

Diepvens, K., et al. "Effect of Whole versus Processed Foods on Thermic Effect of a Meal." (Cheese sandwich crossover study.) Food & Nutrition Research. The whole food vs. processed food study behind the 19.9% vs. 10.7% thermic effect figures. https://foodandnutritionresearch.net/index.php/fnr/article/view/433

Levine, J.A., Eberhardt, N.L., Jensen, M.D. "Role of Nonexercise Activity Thermogenesis in Resistance to Fat Gain in Humans." Science, 1999. The controlled overfeeding study behind the NEAT and 10-fold fat storage variance figures. https://www.science.org/doi/10.1126/science.283.5399.212

This post reflects current research as well as clinical insight and experience. It's intended for educational purposes and isn't a substitute for personalized medical or nutrition advice.