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Adaptive Thermogenesis · The Invisible Counterforce
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In one pass When the scale stalls a few weeks into a serious cut, it is usually not secret snacking, and it is not a broken metabolism. Not this — I can't lose weight because my metabolism is slow — Measured carefully, adults who called themselves diet-resistant had underestimated what they ate by about 47% and overstated their exercise by about 51% (Lichtman 1992, NEJM). Resting metabolism differs between people by only ±200 kcal — far smaller than that reporting gap.
Educational content, not medical advice — consult a clinician.
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Chapter 1
Why the scale stops moving
When the scale stalls a few weeks into a serious cut, it is usually not secret snacking, and it is not a broken metabolism. After weight loss, the calories the body actually burns each day run lower than what a calculation based on the new weight and body composition would predict. This is adaptive thermogenesis. Of two people at the same weight, the one who got there from a heavier weight often burns less each day, and the gap can last a long time.
It is an energy-saving response to shrinking reserves, not damage to an organ. Giving leptin back to people who have lost weight reverses most of the slowdown, which shows it is a reversible change in signaling. That is why cutting calories even harder often just pushes this defense deeper.
It is an energy-saving response to shrinking reserves, not damage to an organ. Giving leptin back to people who have lost weight reverses most of the slowdown, which shows it is a reversible change in signaling. That is why cutting calories even harder often just pushes this defense deeper.
Mechanism · Why the scale stops
Almost everyone who diets seriously hits the same wall around week 4–8: the scale stops moving. You are still weighing your food and you have not skipped a workout, but the number will not come down, and sometimes it ticks back up.The first explanations people reach for are almost always wrong:
I must have eaten something and forgottenMy willpower has collapsedI have broken my metabolism
The more likely explanation is that the body has switched on a whole defense, called adaptive thermogenesis: after weight loss, your total daily energy expenditure (TDEE, the sum of everything you burn in a day) runs lower than your new weight and lean mass would predict. The 2010 review by Rosenbaum and Leibel puts a size on it: while people keep off 10% or more of their body weight, 24-hour energy expenditure is 10–15% below what their body composition predicts, or about 300–400 kcal a day. In other words, of two people who both weigh 70 kg — one who has always weighed 70 kg and one who got down from 85 kg — the second has to eat roughly three to four hundred kcal a day less to hold that weight, and the gap lasts a long time.
The 6-year follow-up of The Biggest Loser (Fothergill 2016) took this to an extreme:
14 contestants on a televised weight-loss competition had lost an average of 58 kg by the end of the 30-week show.6 years later, 13 of them had regained a lot of weight, about 41 kg on average.Yet their resting metabolic rate (RMR, what the body burns each day lying quietly at rest) was still about 500 kcal/day below what their body composition and age at the time predicted.And the slowdown did not track the regain the way people expect: those whose metabolism had dropped most at the end of the show did not regain more; instead, those who were keeping off more weight at 6 years had the larger slowdown at that point. The authors read this as a proportional but incomplete response to the current effort to hold weight down.This is 14 people after extreme, rapid weight loss, and it cannot be applied directly to ordinary dieting. It shows the direction and the persistence, not that everyone will burn 500 kcal less.
This is not the "metabolic damage" story. No mitochondria or thyroid glands were "broken" in these studies, and all the clinical markers stayed within the normal range. A common explanation is evolutionary: in ancestral environments, a large drop in body weight usually meant famine, and the body's job was to keep you alive, not to make you leaner, so it pushes expenditure down and hunger signals up as far as it can.
Understanding this changes two things:
No more self-blame: a plateau does not mean you have failed; the body is running a very old program.No more white-knuckling: "eating another 200 kcal less" often pushes this defense deeper. The more reasonable move is to give the body time to stop treating the situation as a famine, for example with a planned diet break (see the chapter How to respond to a plateau).
The routes by which expenditure is pushed down are covered in two chapters: How the body turns down its burn and Everyday movement quietly drops.
Myth · I broke my metabolism
When a plateau hits, the internet's favorite line is "you broke your metabolism by dieting, and it's permanent". The sentence is half right and half wrong, and taking it apart keeps you from scaring yourself.The right half: after weight loss, energy expenditure really is pushed down, and it can stay down for a long time. Fothergill's 6-year data already show that.
The wrong half, and the one that matters most: the word "broke" implies irreversible organ damage — broken mitochondria, a ruined thyroid, a metabolism "permanently slowed". Small experiments by Rosenbaum's group saw the opposite. When people who had lost weight and were holding it were given leptin back (the hormone fat tissue releases to tell the brain how large its reserves are), most of the drops in 24-hour expenditure, in the energy spent on activity, in sympathetic nervous tone and in thyroid hormone returned to pre-weight-loss levels. The one thing that barely moved was resting expenditure itself. So this is not broken hardware. It is a brain that eased off the accelerator after receiving a "reserves are low" signal; change the signal, and the regulation can come back.
Why the distinction matters:
If you believe your metabolism is "permanently broken", it is easy to give up entirely, or to try to "fix" it with even more extreme dieting, which only presses the defense down harder.If you understand it as reversible signaling, the direction is clear: not harder, but enough signal that the body stops treating things as a famine. Diet breaks, slower loss and keeping muscle all do exactly that (see the chapter How to respond to a plateau).
Giving leptin is an experimental tool, not a weight-loss treatment: it does not make people with ordinary obesity lose weight, and it is used here only to show that the slowdown is driven by signals. So the next time you see the words "metabolic damage", ask one question first: does it mean real organ damage, or reversible down-regulation of signals? In almost every fat-loss situation, it is the second.
Chapter 2
How the body turns down its burn
When you diet, total daily expenditure falls, and part of that fall is expected: the body is lighter and has less tissue to maintain. Adaptive thermogenesis is the extra drop on top. According to Rosenbaum's review, most of that extra drop is not in resting metabolism but in the energy spent on activity: muscles do the same movements more economically, and people may also move less.
The upstream switch is thought to be leptin. Less fat means less leptin, which the hypothalamus reads as low reserves; downstream, sympathetic nervous tone and the thyroid hormone both fall a little. Give leptin back to people who have lost weight and most of these drops return to where they were, which shows the machine is not broken — the brain is saving power.
The upstream switch is thought to be leptin. Less fat means less leptin, which the hypothalamus reads as low reserves; downstream, sympathetic nervous tone and the thyroid hormone both fall a little. Give leptin back to people who have lost weight and most of these drops return to where they were, which shows the machine is not broken — the brain is saving power.
Mechanism · How leptin, T3 and sympathetic tone link
First, split a day's expenditure into its parts: resting expenditure (what you burn lying quietly, roughly 60–70% of the total), the thermic effect of food (the energy spent digesting it), and activity expenditure (everything spent moving, above resting). When you diet, total expenditure falls, partly because you weigh less and have less tissue to maintain — that part is expected.Adaptive thermogenesis is the extra drop on top. The 2010 review by Rosenbaum and Leibel summarizes it: while people keep off 10% or more of their body weight, 24-hour expenditure is 10–15% below what their body composition predicts. Where that drop sits is not consistent across studies:
The thermic effect of food barely changes.Resting expenditure is unchanged in some studies and modestly lower in others.Activity expenditure falls the most and accounts for most of the shortfall below prediction (the review says as much as 85–90%). In inpatient studies, people who had lost weight did not spend less time moving, so the drop more likely comes from muscles doing the same work more economically, not just from moving less.
Three lines thought to drive the drop (same review):
Leptin falls: less fat means less leptin, roughly in proportion to the fat lost (a common estimate is 30–50%). The hypothalamus reads this as low energy reserves, turns down the sympathetic nervous system and the thyroid axis, and pushes up ghrelin (the stomach hormone that makes you want to eat).The thyroid hormone falls a little: in people holding a 10% weight loss, the active thyroid hormone T3 is about 7% lower, and and thyroid-stimulating hormone () are slightly lower too. T3 helps set the cells' baseline heat production and how much energy muscles use.Sympathetic tone falls: the sympathetic nervous system is the part of the autonomic nervous system that presses the accelerator. When its tone drops, heart rate, heat production and fat mobilization all slow.
The three lines are linked: leptin is thought to be the upstream switch, with T3 and the sympathetic system as the downstream effectors. Small experiments by Rosenbaum's group are the key evidence: when people holding a weight loss were given leptin back, most of the drops in total expenditure, activity expenditure, sympathetic tone, T3 and T4 returned to pre-weight-loss levels, while resting expenditure and TSH did not change noticeably. So adaptive thermogenesis is not a "broken metabolic machine"; it is a brain that has received a "save energy" signal and deliberately eased off the accelerator.
Changes you might notice: people often describe a resting heart rate 5–10 beats per minute lower and a body temperature 0.2–0.3 °C lower, but neither figure comes from precise measurements in this review, and individuals vary a lot. Some people treat "morning temperature 0.3 °C below usual and resting heart rate 5 or more beats per minute slower" as the cue to consider a diet break; that too is a rule of thumb. The thyroid changes are small and usually stay within the normal range on a lab report.
What this means:
Do not look only at thyroid tests: feeling cold and sleepy with a lowish heart rate during a diet, while thyroid tests are normal, is usually this energy-saving response, not an underactive thyroid. But if a low heart rate comes with dizziness or fainting, your periods stop, or the symptoms do not ease after you stop dieting, see a doctor rather than deciding for yourself.Strength training protects muscle: resting expenditure is set mainly by lean mass, so resistance training plus enough protein (a common recommendation is 1.6 g/kg a day) is the core of holding this part steady. The Longland 2016 trial supports the direction "high protein plus training preserves muscle", but it compared 2.4 with 1.2 g/kg, in 40 young men, for only 4 weeks.
In practice · Three home signals of energy saving
You do not need a metabolic ward to get a rough sense of whether your body has slipped into "power-saving mode". The three indicators below can be logged at home, and together they are more reliable than any single number. To be clear: this approach is reasoned from the mechanism, and these cut-offs have not been validated as a diagnostic tool.Morning temperature: measure it each day right after waking, before you get out of bed. If, a few weeks into a diet, it stays 0.2–0.3 °C below your usual baseline, treat that as one piece of circumstantial evidence that thyroid hormone has come down.Resting heart rate: also measured on waking, or read the lowest overnight heart rate from a wrist tracker. Staying 5–10 beats per minute below your usual suggests that sympathetic tone has been turned down.How you feel: being cold all the time, sleepy, unable to get going for training, and noticeably more preoccupied with food — this is not being dramatic; it is the felt version of the brain's alarm after leptin falls.
Two points on using them:
Watch the trend, not a single day: temperature and heart rate move around from day to day, and sleep, alcohol and the menstrual cycle all interfere. Judge by the direction over 7–14 days, not by one day's number.They mean something only together: one low reading may just be a bad night; temperature, heart rate and how you feel all trending down together is the cue to consider a diet break (how to do one is in the chapter How to respond to a plateau), not to cut another 200 kcal.
One safety note: feeling cold and sleepy with a lowish heart rate during a diet, while thyroid tests are normal, is usually this energy-saving response, not an underactive thyroid, and does not need medication. But a low heart rate with dizziness or fainting, periods that stop, or weight falling fast and not stopping go beyond the normal response to dieting — see a doctor.
Chapter 3
Everyday movement quietly drops
Non-exercise activity thermogenesis (NEAT) is the energy spent on everything that does not count as exercise: walking to the bathroom, housework, typing, gesturing while you talk, jiggling a leg while seated, standing instead of sitting. In ordinary people it comes to about 100–800 kcal a day, varies enormously between individuals, and is the biggest source of difference in total expenditure between two people of the same weight.
The best-known evidence comes from overfeeding. In Levine 1999, 16 non-obese adults ate 1000 kcal a day above their needs for 8 weeks. The fat they gained ranged from 0.36 kg to 4.23 kg, a more than tenfold difference, and changes in NEAT explained most of it. Dieting runs the other way: by the same regulation, NEAT should be turned down, and you can hardly notice it yourself.
The best-known evidence comes from overfeeding. In Levine 1999, 16 non-obese adults ate 1000 kcal a day above their needs for 8 weeks. The fat they gained ranged from 0.36 kg to 4.23 kg, a more than tenfold difference, and changes in NEAT explained most of it. Dieting runs the other way: by the same regulation, NEAT should be turned down, and you can hardly notice it yourself.
Mechanism · How daily activity is quietly turned down
What else the overfeeding experiment showed: a rough calculation says the extra energy in Levine 1999 (Science) was enough to add about 7 kg of fat to each volunteer, yet the actual gain differed more than tenfold. About two-thirds of the rise in total expenditure came from NEAT, and the people who gained the least fat increased their NEAT by close to 700 kcal a day — without realizing they were moving more, their bodies burned off the surplus for them. This was a small experiment, and it ran in the direction of overeating; it shows that NEAT can adjust itself by a large amount.Dieting runs the other way: by the same regulation, NEAT should be turned down. The usual picture:
You walk more slowly (from 1.4 m/s to 1.2 m/s, for example, without feeling any difference; to give a sense of scale, a 30-minute commute might burn about 30 kcal less)You jiggle your leg, shift position and adjust your posture less while sitting"I'll stand while I wait" quietly becomes "I'll sit while I wait"You gesture less while talking, feel less restless, and the whole person goes into "power-saving"The stairs become the elevator, and a short walk becomes a shared bike
The key is that you cannot feel any of this. NEAT is turned down by the part of the nervous system that runs without conscious control, unlike "I don't feel like training today", which you clearly notice. A step-counting band may not show it either: your step count can look about the same while the same movements cost less energy. Rosenbaum's review points out that a large part of the fall in activity expenditure after weight loss likely comes from muscles doing work more economically, not only from moving less; in inpatient studies, people who had lost weight did not spend less time moving.
How much NEAT can fall during a diet: rough estimates are 200–300 kcal a day, and 500 kcal or more in very aggressive diets, but these figures come from different studies and vary a lot between people. It is often less visible and harder to track than the change in resting metabolism, and it is one common reason for "my tracker says my activity hasn't changed, but the scale won't move".
How to push back:
Treat a daily step floor as non-negotiable (for example 7–10k steps a day): it puts NEAT on a track you can see, so it cannot slip away unnoticed.Keep your strength training frequency: resistance training protects muscle directly, and keeps you out of "hibernation mode".Do not judge by feel whether you moved enough today: your sense of it is being recalibrated by the same regulation and is unreliable. Use objective records (steps, heart rate, a training log).
Chapter 4
How long the slowdown lasts
The most uncomfortable thing about adaptive thermogenesis is that it does not vanish in a few weeks; it can last months to years, which is one reason regain after weight loss is so common.
In Sumithran 2011 (NEJM), 50 people with overweight or obesity and no diabetes lost weight on a very-low-energy diet for 10 weeks, an average of 13.5 kg, and a panel of appetite-regulating hormones was measured before the diet, at week 10 and at week 62. A year later, leptin, the satiety signals PYY and CCK, and insulin were still low, ghrelin was still high, and people still felt hungrier than before the diet. The study measured appetite hormones only, not , sympathetic tone or everyday activity; what it shows is that the signals on the "wanting to eat" side take a long time to return.
In Sumithran 2011 (NEJM), 50 people with overweight or obesity and no diabetes lost weight on a very-low-energy diet for 10 weeks, an average of 13.5 kg, and a panel of appetite-regulating hormones was measured before the diet, at week 10 and at week 62. A year later, leptin, the satiety signals PYY and CCK, and insulin were still low, ghrelin was still high, and people still felt hungrier than before the diet. The study measured appetite hormones only, not , sympathetic tone or everyday activity; what it shows is that the signals on the "wanting to eat" side take a long time to return.
Evidence · How long the signals take to reset
What Sumithran 2011 actually found: after 10 weeks of weight loss, leptin, PYY, CCK, insulin and amylin had fallen, ghrelin, gastric inhibitory polypeptide (GIP) and pancreatic polypeptide had risen, and subjective appetite had increased. At week 62, more than a year after the weight loss, leptin, PYY, CCK, insulin, ghrelin, GIP and pancreatic polypeptide were still different from before, and hunger was still higher. Glucagon-like peptide-1 () was measured too, but it was not on the list of hormones still off baseline. The authors concluded that the appetite signals that encourage regain had not returned to their earlier levels a year after the weight loss.So people who have lost weight are not fighting "a lack of self-control" every day; they are up against a whole hormonal background reminding the brain "you are owed a meal". Put in one sentence, the body behaves as if it remembers being heavier, and for a long time it tries to get back there.
The Look AHEAD long-term trial (Look AHEAD Research Group 2013, NEJM): 5145 people with overweight or obesity and type 2 diabetes were randomly assigned to an intensive lifestyle intervention or to a diabetes-education control group.
At year 1, the intervention group had lost 8.6% of body weight, the control group 0.7%.By the end of the study (median follow-up 9.6 years), the figures were 6.0% and 3.5%, a gap of about 2.5 percentage points — most of the difference had been taken back.The primary outcome (cardiovascular death, non-fatal heart attack, non-fatal stroke or hospitalization for angina combined) was not reduced, and the trial was stopped early after a futility analysis.The lesson: the people who keep weight off for the long term are a minority, and maintenance needs a long-term strategy, not a few months of effort.
Why it lasts so long:
One explanation is the set-point hypothesis: the brain treats a weight it "knows" as a target to defend and uses hormones to pull deviations back. It is a hypothesis, not a settled fact.If the hypothesis holds, the set point may drift down slowly, but only after years of stable maintenance, not as soon as the diet ends; this step has not been measured directly.It would also explain why people who have never been heavy do not gain easily, while people who went from heavy to lean struggle to maintain: at the same 70 kg, the signals behind the two of them are different.
What this means:
Success in a diet is not the number on the scale; it is still holding it 1–3 years later.Maintenance is the main battlefield, not "I'm done, time to relax".Slower may hold better: coaches and researchers generally believe that weight lost at 0.5% a week is easier to keep off than weight lost at 1.5% a week, but direct comparisons are limited (how to do it is in the chapter How to respond to a plateau).Accept the reality: according to Rosenbaum's review, to hold your weight you may need to eat about 300–400 kcal a day less than someone of the same weight who "has never been heavy". That is how the body is set, not something you did wrong.
Chapter 5
How to respond to a plateau
The answer to adaptive thermogenesis is not harder, faster or less food; it is giving the body enough signal that it no longer needs to defend. Raising calories back to maintenance for a planned week or two should, by the mechanism, let leptin and recover partly — that is maintenance, not eating freely. Add slower loss, resistance training to keep lean mass, and protein and sleep to hold hunger signals down.
A plateau is often part of the process, not a failure. If your weight is flat but your waist is shrinking, you may still be doing the right thing.
A plateau is often part of the process, not a failure. If your weight is flat but your waist is shrinking, you may still be doing the right thing.
In practice · Six ways to respond to a plateau
Once you understand adaptive thermogenesis, the direction of the response is clear: not harder, not faster, not less food, but giving the body enough signal that it no longer needs to defend.1. Planned diet breaks (1–2 weeks back at maintenance calories)
It is not "falling off the wagon"; it is a tool. Every 6–12 weeks of dieting, deliberately return to maintenance calories for 1–2 weeks. By the mechanism, this should let leptin and recover partly.Compared with continuous dieting, intermittent energy restriction (cut for a while, maintain for a while) produces similar weight loss in most ; whether it protects metabolism and lean mass better is inconsistent across studies and not settled.It matters psychologically too: breaking the feeling of "always going hungry" makes it easier to keep going over the long term.The key: a diet break is maintenance, not a calorie surplus. Do not let it turn into a cycle of "refeed → binge → guilt".
2. Go slower (0.5–0.7% of body weight a week)
For a 70 kg person, 0.35–0.5 kg a week is enough.By the mechanism, losing too fast (more than 1% a week) should make the energy-saving response stronger, push NEAT down further and cost more muscle. Coaches and researchers widely hold this view; trials comparing speeds directly are few.A possible extra benefit of slow loss: maintenance may be easier.Taking a few more months is not slow; it is the difference between finishing the job and finishing half of it and then bouncing back.
3. Put resistance training first, to hold resting metabolism
Resting metabolism is set mainly by lean mass. Each 1 kg of muscle lost during a diet lowers resting expenditure by about 13 kcal a day for the long term.2–3 full-body resistance sessions a week is the minimum dose; heavy compound movements (squat, push, pull) come first.Do not drop cardio entirely, but creating the deficit through cardio is inefficient: the energy-saving response quickly compensates for that expenditure.
4. Protein at ≥ 1.6 g/kg a day
Longland 2016 (AJCN) was a proof-of-principle trial: 40 young men, 4 weeks, an energy deficit of about 40%, and hard training 6 days a week. The group eating 2.4 g/kg of protein a day gained 1.2 kg of lean mass; the group eating 1.2 g/kg gained only 0.1 kg. It shows that high protein with a lot of training can hold, or even add, lean mass during a deficit, but the population was narrow and the trial was short.The dose-response for preserving muscle is generally thought to run between 1.6 and 2.2 g/kg.Protein's thermic effect is as high as 25–30%, so the net calories it leaves you are lower than the label says.Protein is the most filling macronutrient and directly eases the hunger that ghrelin drives.
5. Sleep enough (≥ 7 h)
Too little sleep amplifies this defense: leptin falls, ghrelin rises and insulin sensitivity drops.Nedeltcheva 2010 was a crossover trial: 10 adults with overweight each went through the same calorie restriction for 14 days twice, once with 8.5 h of sleep opportunity and once with 5.5 h. They lost about the same weight both times, but its make-up changed: with 5.5 h, about 80% of the weight lost was fat-free mass (muscle, water and so on) and fat fell by only 0.6 kg; with 8.5 h, about 50% was fat (1.4 kg).Sleep is the cheapest and most neglected fat-loss tool.
6. Accept the plateau as part of the process, not a failure
4 weeks of flat weight does not mean nothing is changing: body fat may be falling, muscle rising and water shifting.Tell a real plateau from a false one: track weight (a 7-day moving average), measurements (waist, thigh), training performance and photos together.If your weight is flat but your waist is shrinking, you are doing the right thing.If nothing at all has moved for 4–6 weeks, start a diet break rather than cutting another 200 kcal.
In practice · How to actually run a diet break
A diet break sounds simple, but done wrong it easily slides into a cycle of "falling off the wagon → bingeing → self-blame". Treat it as a tool with clear rules, not a free-for-all.Timing and rhythm:
When to start: after 6–12 weeks of continuous dieting, or when the three signals from the chapter How the body turns down its burn (temperature, heart rate, how you feel) keep trending down. Do not wait until you cannot take it any more and stop by default.How long: 1–2 weeks. Too short, and leptin and do not have time to recover partly; too long, and it drifts into regaining fat.
Core rules (in one line: maintenance, not surplus):
Calories back to maintenance, not eating freely: raise your intake to the maintenance level for your current weight, not "anything goes this week". The extra calories come mainly from carbohydrate (which helps leptin and glycogen recover), and protein stays the same.Protein unchanged at ≥ 1.6 g/kg: do not relax it during the break; it is the floor that protects muscle.Keep training: do not stop strength training. The extra energy is best spent pushing your training performance, which is also how you steer calories toward muscle rather than fat.Set your expectations: over these 1–2 weeks your weight will rise by 1–2 kg as glycogen and water come back. That is water, not fat, so do not panic at the scale; it drops back quickly once you return to a deficit.
The evidence behind it: intermittent energy restriction (cutting for a while, maintaining for a while) produces weight loss similar to continuous dieting in most , with inconsistent results on whether it preserves lean mass better. Longland 2016 showed that, in a large energy deficit, high protein plus a lot of training let young men gain lean mass over 4 weeks. The logic of a diet break combines the two: give the body a breathing signal without losing muscle. The combination itself has not been tested in its own trial.
If you find that every diet break gets away from you and slides into bingeing, the problem is usually not calories but emotion and the food around you. That thread needs to be faced on its own, with help from a doctor or another professional if needed.
References · 7
- Fothergill, E., Guo, J., Howard, L., Kerns, J. C., Knuth, N. D., Brychta, R., Chen, K. Y., Skarulis, M. C., Walter, M., Walter, P. J., & Hall, K. D. (2016). Persistent metabolic adaptation 6 years after 'The Biggest Loser' competition. Obesity, 24(8), 1612–1619. 14 of the 16 original 'Biggest Loser' competitors re-measured 6 years later (DXA, indirect calorimetry). End of the 30-week competition: weight -58.3 kg, resting metabolic rate (RMR) -610 kcal/day. At 6 years: 41.0 kg regained, RMR still 704 kcal/day below baseline, and metabolic adaptation (RMR residual after adjusting for body composition and age) -499 ± 207 kcal/day. Regain was not correlated with metabolic adaptation at the competition's end (r = -0.1, P = 0.75), but those maintaining more weight loss at 6 years had greater concurrent metabolic slowing (r = 0.59, P = 0.025); the authors call adaptation a proportional but incomplete response to contemporaneous efforts to reduce weight (abstract, PMID 27136388). 10.1002/oby.21538
- Rosenbaum, M., & Leibel, R. L. (2010). Adaptive thermogenesis in humans. International Journal of Obesity, 34(Suppl 1), S47–S55. Narrative review. Maintaining a 10% or greater reduction in body weight is accompanied by an approximate 20-25% decline in 24-hour energy expenditure; this fall in weight-maintenance calories is 10-15% below what is predicted from the changes in fat and lean mass, so a formerly obese person needs ~300-400 fewer calories a day than a never-obese person of the same weight and composition. Non-resting energy expenditure accounts for as much as 85-90% of the decline below predicted values, and skeletal-muscle work efficiency at low exercise levels rises by about 20%. Circulating T3 shows 'small but statistically significant decreases' - the review gives no percentage. Short-term leptin given to weight-reduced subjects, restoring pre-weight-loss leptin levels, reverses the lower energy expenditure, thyroid hormone and sympathetic activity, the higher muscle efficiency and the increased energy intake. The abstract cites an over 80% recidivism rate after weight loss (abstract, PMID 20935667; full text, PMC3673773). 10.1038/ijo.2010.184
- Longland, T. M., Oikawa, S. Y., Mitchell, C. J., Devries, M. C., & Phillips, S. M. (2016). Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: A randomized trial. American Journal of Clinical Nutrition, 103(3), 738–746. 40 young men (20 per group), 4 weeks at a ~40% energy deficit with resistance training plus high-intensity intervals 6 days a week; 2.4 vs 1.2 g protein/kg/day. Lean body mass +1.2 ± 1.0 kg vs +0.1 ± 1.0 kg; fat mass -4.8 vs -3.5 kg; exercise performance improved similarly in both groups. The authors call it a proof-of-principle trial (abstract, PMID 26817506). 10.3945/ajcn.115.119339
- Levine, J. A., Eberhardt, N. L., & Jensen, M. D. (1999). Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science, 283(5399), 212–214. 10.1126/science.283.5399.212
- Sumithran, P., Prendergast, L. A., Delbridge, E., Purcell, K., Shulkes, A., Kriketos, A., & Proietto, J. (2011). Long-term persistence of hormonal adaptations to weight loss. The New England Journal of Medicine, 365(17), 1597–1604. 50 overweight or obese adults without diabetes on a 10-week very-low-energy diet; mean loss 13.5 kg. Measured at baseline, 10 and 62 weeks: leptin, ghrelin, PYY, GIP, GLP-1, amylin, pancreatic polypeptide, CCK, insulin and subjective appetite. At 62 weeks, leptin, PYY, CCK, insulin, ghrelin, GIP, pancreatic polypeptide and hunger still differed significantly from baseline; GLP-1 and amylin are not in that list. No thyroid hormone or energy-expenditure measure is reported in the abstract (abstract, PMID 22029981). 10.1056/NEJMoa1105816
- The Look AHEAD Research Group. (2013). Cardiovascular effects of intensive lifestyle intervention in type 2 diabetes. The New England Journal of Medicine, 369(2), 145–154. 5,145 overweight or obese adults with type 2 diabetes randomized to an intensive lifestyle intervention or diabetes support and education. Stopped early for futility at a median follow-up of 9.6 years. Weight loss 8.6% vs 0.7% at 1 year and 6.0% vs 3.5% at study end. Primary composite (cardiovascular death, nonfatal MI, nonfatal stroke, hospitalized angina): 403 vs 418 events, HR 0.95 (0.83-1.09), P = 0.51 - cardiovascular events were not reduced (abstract, PMID 23796131). 10.1056/NEJMoa1212914
- Nedeltcheva, A. V., Kilkus, J. M., Imperial, J., Schoeller, D. A., & Penev, P. D. (2010). Insufficient sleep undermines dietary efforts to reduce adiposity. Annals of Internal Medicine, 153(7), 435-441. Randomized 2-period crossover, 10 overweight adults, 14 days of moderate caloric restriction at 8.5 vs 5.5 h sleep opportunity. ⚠️ DIRECTION: sleep curtailment DECREASED the proportion of weight lost as fat by 55% (1.4 vs 0.6 kg) and INCREASED loss of fat-free body mass (1.5 vs 2.4 kg). Total weight lost was the same; the tissue changed. The L4 stage used to state this backwards and date it 2009. 10.7326/0003-4819-153-7-201010050-00006