About a month ago I posted on a Swedish overfeeding study and how the results were misreported in the press. This study showed that increased carbohydrate intake can cause an increase in certain liver enzymes associated with the metabolic syndrome. Along with this liver enzyme data the authors reported on metabolic rate changes that are instructive in our quest to determine the existence (or lack thereof) of the metabolic advantage.

I would imagine that most people reading this blog have had problems with excess weight sometime in their pasts. Those of you who have struggled with overweight probably have little sympathy for those who have the opposite problem – that of inability to gain. Despite how easy it seems for those with weight problems to gain weight and especially to regain lost weight, it is extremely difficult for many people to gain weight almost irrespective of how much they try.

The medical literature is full of overfeeding studies in which subjects are encouraged to eat substantially greater amounts of food than they typically eat in an effort to get them to gain weight. Probably the most famous of these are the Vermont prison overfeeding study conducted by Ethan Sims back in the 1970s. These studies, like the starvation studies of Keys, would probably never make it past the ethics review today, and will likely never be repeated.

Sims and his team overfed prisoners and found that despite being overfed the same number of calories there were large differences in the rate of weight gain between individuals. And he discovered that when the overfeeding stopped, there were differences in the rates at which inmates lost the weight they had gained. One of the lessons from these studies is that individuals have different predispositions to gain and lose weight independent of caloric intake.

Another lesson is that overfeeding tends to increase metabolic rate, allowing a dissipation of many of the excess calories consumed. As I’ve pointed out before, the calories in/calories out part of the energy balance equation are not independent variables. In other words just because you decrease (or increase) calories in doesn’t mean that calories out stays the same. Virtually all overfeeding studies show that there is much less weight gain than the increased caloric intake would predict. This effect is so common that German researchers in the early 20th century gave it the name luxusconsumption, meaning the wastage of calories by increasing metabolic rate during overfeeding.

We can see luxusconsumption at work in the Swedish fast food overfeeding study. The authors were a little hazy about the actual caloric consumption of the subjects, reporting it differently in two places, so we really can’t use their figures for our own calculations. The table below shows the increases in weight and metabolic rate during the 28 day study. We can make some calculations from these numbers.
Since the data isn’t broken out by male/female I did my calculations based on all the subjects being male since two thirds of them were. I worked backward from the BMI and calculated the average height of the subjects as being 176 cm.

I used the Harris-Benedict equation to determine starting and ending resting metabolic rates (RMR). The Harris-Benedict equations were developed in 1919 and have been used extensively since then. A few researchers have come along and improved on them since, but most of the online RMR calculators use the Harris-Benedict equations, so that’s what I used. These equations assume that given a sex, height, and age that the RMR correlates with weight, which is one of the reasons many people who should know better state categorically that RMR is simply a function of weight.

My calculations show that prior to starting the overfeeding, the average subject should have had an RMR of 2064 kcal/day. After 28 days of overfeeding and a 6.4 kg ( 14 lb) weight gain, the RMR calculates to 2152 kcal/day, about a 4% increase.

When the Swedish researchers measured the RMR directly using the ventilated hood technique they found a starting RMR of 1615 kcal/day that increased to 1813 kcal/day, a little over a 12 % increase.

Weight increased from 67.6 kg to 74 kg, a little over a 9% increase, while the RMR increased by 12% as compared to the 4% predicted by the Harris-Benedict equation. This measured increase in RMR that is greater than the weight gain would predict is luxusconsumption in action.

Another name for luxusconsumption is metabolic advantage. Metabolic advantage is defined as a lesser weight gain than a given number of extra calories consumed would predict, and is brought about by an increase in metabolic rate driven by the diet. In other words, calories in increase calories out to a greater extent than the calories in. The subjects in this study were definitely experiencing a metabolic advantage.

As more calories are consumed, luxusconsumption increases. And this effect takes place irrespective of the type of calories – macronutrients – consumed. The metabolic advantage is firmly established in the medical literature dating back over 100 years and was once again confirmed in this study. The debate we’ve been having is whether there is a different metabolic advantage for differing macronutrient consumption, i.e., does restricting carbs produce more of a metabolic advantage than restricting fat in diets of the same number of calories. We will address this in a future post, but for now I want everyone to realize that a metabolic advantage does exist and has been demonstrated countless times.

Before we proceed to the question of metabolic advantage and macronutrient consumption there is one other notion we need to discuss and clarify: data presented in medical studies as averages of all the data collected. This often confusing issue will be the subject of the next post.

Photo by call me hangry ???????? on Unsplash


  1. Those Swedes are certainly tall!
    Is 196 cm. a typo? I computed 176 cm.
    I misread my calculator. The mistakes have been repaired. Thanks for the heads up.

  2. This is very interesting. Lately I have been reading about the effects of long water fasts (3-6 weeks) and how they improve health. One thing that struck me is how fasting for about 4 weeks generally brings a 6%+ permanent increase in metabolic rate, in that it lasts for years afterward. Since fasting has been praised for thousands of years as having a rejuvenating effect on the body, I’ve been wondering if this accounts for the changes. After all, aging tends to decrease metabolic rate.
    Is the 6 percent increase something you’ve discovered in yourself or is it published in the literature? If it is published in the scientific literature, I would love to see the citation.

  3. In advance of your next post on the subject, I’ll emit my opinion about that. I think that carbs play a role in body composition regardless of quantity. Therefore I think they continue to play the same role in the case of overfeeding. The logic is as follows:
    If overeating = grow heavier
    andit eating carbs = grow fatter
    then overeating carbs = grow heavier and fatter
    if overeating = grow heavier
    andif not eating carbs = grow leaner
    then overeating but not eating carbs = grow heavier and leaner
    It’s oversimplified but it works for me.
    I think you’re on the right track.

  4. and when you say fasting do you mean purely water ?
    I have done a few fasts when a deranged youth….10 days and a few 7 days and thats was a bugger but 4 weeks is a feck of a long time.
    Am dead keen to know where you read this..please advise.
    Many ‘tanks’

  5. I think there is a difference between raw calories and cooked calories, esp when it comes to carbohydrates. I have seen in the past where drinking raw fruit juices (like apple lemon lime) and raw vegetable juices (like carrot) sped up my metabolism tremendously. I felt warmer and lost weight or did not gain, despite eating substantial calories and carbs. I have also seen raw unheated honey does not influence blood sugar as much as normal honey that is cooked and processed. Things like table sugar and corn syrup are obviously different than fresh food that has not been heated or stripped of nutrients. I believe that raw calories in general will cause more thermogenesis than cooked, causing weight loss when needed. Others have reported a gain in weight, when they were extremely thin to start. Years ago, I lost a lot of weight with low-carb diet, but I lost another 10 pounds (175 to 165) by eating raw meat and adding MORE carbohydrates than I had been eating (but only RAW carbohydrates). So, this is another very important factor to consider in the obesity epidemic, IMO.

  6. Mr Levac that might be deeply helpful.
    So exactly do we, the body, lose fat if we take in as many cals as we use plse ?
    This might be a symptom of me not reading the book Good C’s Bad C’s.
    If anyone has interesting links am at supachramp at yahoo.com
    (Am on hols in Rancho Mirage and whilst it’s a ‘smooth uptight everything in its place’ rich whitey enclave the weather and surround is super duper

  7. @simon fellows
    I can’t answer your question with a definite yes or no. This is something I’ve been looking at since I started a low carb diet. But, I got more hints toward the high side of calories being best for fat loss. Maybe it’s due to the increase in expenditure that it brings. Eat more so spend more. However, some say we must also cut calories for best results. I don’t know, try either way and see how that goes. Adjust as necessary. I eat as much as I want (but no carbs as you can understand) and see results anyway. Good results are also seen by others who eat less than I do.
    One significant aspect of low carb is the hunger. I have to remember to eat sometime. I’m barely hungry anymore if ever. This fact alone could account for a reduction in calories but I don’t count calories. Instead, I eat to satiety.

  8. Martin thankee muchly.
    I’ve eaten this way (paleo or whatever other tragic name one gives it..they all sound as daft as the next) for 12 yrs.
    The cutting cals seems to work every so often but perhaps and am only guessing here only if ones in caloric advantage/+ more often than not;if the other way round as Taubes seems to say ones expend. goes doon and thus one does less
    The humbling thang about all this is that for me after recently reading Taubes book (or bits of it thereof) i realized i hadn’t got any idea why we actually lose fat !
    I perhaps knew that low carb diets were seemingly the best way to feel ace when losing fat(ketones fuelling 25% more effic. the ‘eart and noggin so sayeth veech and other ketone-bods) but that aside i knew sweet phuq-all..as the Bishop of Rotherham was fond of saying to me.
    I feel superb most of the time but would like to drop 15-20 pounds but i just canny seem to do it.
    I walk most days for 45 mins at least(for mood elevation) do plyometrics for short bursts, weights for very short periods( matter of minutes’anymore and the quality of mind is lost as it stresses the system oot..presumably cortisol, noreepi and epi?) I eat oscillatying high protein mod fat, higher fat low protein sans being very uptight buyt always low carb.
    Don’t get me wrong its pure vanity the 15-20 pounds and would in no ways sacrifice the quality of mind/being i have for that weight but any pointers would be dandy…from anyone.
    supachramp at yahoo dot com
    Any more enlightenment you could pour my way would be great and if not thanks for what you’ve said.
    The low-carb diet creates the metabolic hormonal milieu allowing fat to be easily released from the fat cells. But if you are eating enough fat calories (or any other kind) to meet all your metabolic needs, you won’t release fat from the fat cells and you won’t lose weight. In order to lose the weight, you’ve got to create a caloric deficit so that fat will need to flow out of the fat cells to meet the body’s needs. Once you’ve lost the weight you need to lose, then keeping carbs low while increasing the calories doesn’t generally put weight back on. You dissipate the extra carbs through the mechanism of luxusconsumption. Add a few carbs to the mix, though, and the weight comes back.

  9. I assumed metabolic advantage exists only when over-consuming massive fat calories. As I recall from Guyton’s text, fat and protein is absorbed through a concentration gradient. Sugar, on the other hand, has a mechanism that allows every last molecule to be absorbed irrespective of the blood sugar level. So once the blood is lipemic, is fat still being absorbed?
    In this Swedish fast food overeating study carbs were increased massively – from 275 g/day to 645 g/day – yet the metabolic advantage was still present. Virtually all of the overeating studies published used large increases of carbs to get the subjects to overeat, yet most showed a metabolic advantage. It’s difficult to get people to overeat without increasing carbs because protein and fat without carbs are too satiating, and people won’t increase food intake very much. Add carbs to the recipe, and the calorie consumption skyrockets. So, the metabolic advantage exists even in the presence of carbs when calories are very high.

  10. Martin Levac, I appreciate your fundamentals! I’ve added a few things…
    If overeating = grow heavier
    andit eating carbs = grow fatter
    then overeating carbs = grow heavier and fatter, GROW BIGGER HEARTS, DEVELOP HEART FAILURE
    if overeating = grow heavier
    and if not eating carbs = grow leaner GROW STRONGER, MORE VITAL
    then overeating but not eating carbs = grow heavier and leaner
    And the sad thing is that today even children and adolescents are currently being affected. The carb industry has completely lured the kids in! The more carbs they eat, the more they crave…
    The more indoors, the more sedentary, ALSO the more vitamin D deficient they become… And the more heart dysregulation, widespread atherosclerosis and heart failure is occurring.
    Please read more here:
    Articles showing a new emerging epidemic in America associated with obese children. very sad, very preventable. Can protein power and other low carb diets be taught to public schools to our young children before it’s too late?

  11. I have also had an interesting experience with VLC and then IF, VLC eating that seems to lend weight to what Martin Levac alludes to. On VLC I effortlessy dropped down to 154 pounds (I am 5’11”). From this low my weight seemed to fluctuate between 155 and 159 pounds. After I added IF my weight crept back up 165 pounds (the weight I was at most of my adult life until about 10 years ago when it went up to 195 pounds).
    On IF I seem to sit on 165 pounds plus or minus a fraction of a pound. The interesting thing is that my weight went up even though my meals on IF are not large. I seldom ever eat large quantities. Nor, do I ever seem to get more than slightly hungry even when I go without food for more than 24 hours. In fact, if I am active, hunger is a non-issue.
    Even more interesting is that when I was in really bad shape about 5 years ago, before I found out I had type II diabetes, I kept getting the urge to not eat. The only reason I did not fast was that I gave in to social pattern of eating regular meals. But it was not driven by hunger which had interestingly enough greatly diminished.

  12. With regards to Bruce Kleisner’s remark about raw meat, i understand that raw meat is far easier to digest than cooked meat. Raw meat typically digests in a much shortet time span than cooked meat. Less energy expelled on digestion means more energy for burning body fat.
    I don’t know if this is true or not, so I can’t really comment.

  13. Hi Dr. Eades:
    If our metabolic advantage is intact and working most effectively by eating the right macronutrients, how do excess calories or calorie deficits impact us? I am sure you will cover this but bear with me….
    I have no problem controlling my macronutrient intake by eating high protein, low carb and understand why I need to for optimal general health and to maintain my lean muscle mass but get puzzled about the calorie issue if I want to lose fat (perhaps, some cognitive dissonance going on here due to my family using calorie control to successfully lower their weight most of my life).
    Here are my questions then:
    Is reducing my calories (while eating enough protein and a little carbs as possible) as low as possible better? will it cause faster fat loss?
    If I do need to control my calorie intake (assuming that I am eating the correct amount of protein and keep my carb intake low), what is the best way to calculate the amount of calories to eat for fat loss?
    thanks very much!
    Yes, you will lose faster if you reduce your calories, even with low-carb. The metabolic changes brought about by a true low-carb diet will allow the fat cells to easily give up their fat. But the fat cells don’t need to give up their fat (even though they can) if you are eating enough fat calories to meet your body’s needs. You’ve got to create the deficit to get the fat out of the fat cells.

  14. Freddy: “fasting for about 4 weeks generally brings a 6%+ permanent increase in metabolic rate, in that it lasts for years afterward.”
    AFAIK, the opposite is true. Prolonged fasting will decrease your metabolism by at least 10%, from the loss of lean mass and attempts to conserve energy. Where did you hear that fasting would permanently increase your metabolic rate? That doesn’t even make any sense. It does increase growth hormone vastly and may have rejuvenating and detoxifying effects. But most will rapidly regain the weight lost and then some when they break the fast.

  15. I’d like to read the archives, but they just keep flashing back to the main page.
    Thanks for the heads up. I’ve got a message in to my web guy to get it fixed.

  16. I’m beginning to wonder if the metabolic advantage that is causing so much hoopla stems from a formula in which all of the variables are unknown or improperly calculated. And then there’s individual variation, which could be expressed as even more variables and uncertainty.
    While all of this is interesting from an academic standpoint, it’s not something I’m going to base my daily life around. If it appears to happen to me; great, if not, I’m certainly not going to obsess over it and wonder what I’m doing wrong. It’s hard enough staying on VLC without stressing about other things out of my control.
    Excellent decision.

  17. Peter, yes, raw meat does digest a lot faster, as I understand it. So, whereas cooked beef and lamb might take 4-5 hours and cooked pork 6 hours to digest, the raw equivalent may take less than an hour. Another factor is that the raw fat has lipase enzymes, which might speed up the burning of excess fat in people who are metabolically resistant.
    I don’t eat all raw, as I’ve said before, but I have eaten raw beef, lamb, pork, chicken, salmon, shellfish, liver, eggs, milk, cheese, cream, and other things without any food poisoning. I’d say you’re more likely to get food poisoning from fast food and restaurant food high in processed vegetable oils, lunch meats, salad dressings, and things of that sort. I think the paranoia about microbes is rather silly. Humanity would be dead if it were true.

    Most people create a caloric deficit simply by going on a low-carb diet because the diet is so satiating. Some, however, can eat large enough amounts of low-carb foods to prevent weight loss, which may be what’s happening in your case. In my experience the three things that tend to sabotage low-carb diets are cheese, nuts and nut butters. People can consume huge numbers of calories of these foods without exceeding their carb limitation. If you are eating a fair amount of these foods and cut back on them, your weight loss should pick up.

  19. LANA KAY, you are probably not eating enough fat. Aim for 50% more fat than protein, at least. This is a common pitfall. Try basing your meals around fat instead of protein. Pick fattier foods and eat the fat before the lean part. Make sure you don’t waste the fat if you cook food. Eat with a spoon and serve yourself with a ladle or solid spoon. Things like cream cheese are very hard to over-eat on a low-carb diet. Likewise fatty meat, egg yolks, etc. If you don’t focus on fats, your appetite won’t be controlled and weight loss will be stalled.

  20. I think you should aim for 50% more grams of fat than protein on low-carb diet. This controls appetite to where you shouldn’t be hungry much. The less fat, the more hunger, the harder it is to lose weight. Mike brought up a great point about cheese and nuts. Also, I would not eat too many nuts, because most are high in omega-6. Macadamias and hazelnuts are fairly low. I’m also a fan of coconut oil or coconut butter if you like some fiber in it. Many stores have young coconuts. I think it’s best to shell nuts by hand so you don’t eat too many at a time. Chew them thoroughly, to prevent choking and improve digestion. For cheese, take a reasonable portion and put the rest away. It’s very dense compared to most foods, so don’t just nibble mindlessly. Look for cheese with plenty of fat: cheddar, colby, or cream cheese. Calories count for weight loss, but I think a low-carb prevents creeping obesity and weight gain, unlike the typical high-fat AND high-carb diet (SAD). Fat keeps you satisfied.

  21. I wasn’t sure where to ask this question. I recently saw an article that stated that women have a much higher risk of miscarriage if they are on a high protein diet. Here is the link:
    I know this is an old article. Has it been discredited? I had heard the opposite — that a high carb diet reduces fertility.
    It’s a study in mice that has no bearing on what happens in humans. Mice aren’t designed to live on higher protein diets, so their response to them is a valid indication of what happens to humans.

  22. Dr. Eades,
    I’m visiting this site nearly a year after the last comment was posted but hope you’ll notice this comment and respond.
    As far as I know, researchers have always ignored what I call the “bacterial heat factor” (BHF). Organic gardeners, who make their own compost, know that when bacteria feed and multiply, they produce heat. Moreover, under anaerobic conditions such as found in the colon, energy-containing gasses such as methane are produced. Consequently, any calculation of total energy absorption from the small intestine must include the following: 1) heat lost during urination and defecation; 2) heat that diffuses into the body as waste material moves through the gut and; 3) energy ejected when gas is passed.
    Perhaps the BHF explains (at least in part) why increases in caloric intake either translate into less weight weight gain than expected (metabolic advantage) or don’t translate into any weight gain at all. For example, BHF may explain the discrepancy between measured caloric intake and weight loss noted by Dr. Penelope J. Greene in her 2003 low-carb/low-fat comparison study. http://www.news.harvard.edu/gazette/daily/0310/20-lowcarb.html
    Theoretically, bacterial activity in the gut is proportional to the amount of digested and undigested food calories that don’t get absorbed into the bloodstream. Moreover, the ability of the digestive system to transfer digested calories from the small intestine to the bloodstream depends upon physiological factors such as stomach size, intestinal surface area, and (I suspect) the number of receptor sites lining the small intestine.
    In a 1981 FAO report entitled ENERGY ABSORPTION AND DIETARY FIBRE http://www.fao.org/DOCREP/MEETING/004/M2763E/M2763E00.HTM the authors note that “Faecal energy losses arise from several sources, including endogenous waste material such as mucus and exfoliated mucosal cells, bacterial cell mass from the intestinal flora, and finally undigested food residues themselves.” Overfeeding likely generates proportionately more undigested food residue for bacteria to feed on.
    The authors also noted that “The total available energy of a food may be defined simply as its heat of combustion, minus the heat of combustion of the faecal and urinary residues to which it gives rise.” I’d say that this is an oversimplification! They’ve ignored the BHF.
    More recently, on page 3 of a February 2008 article published in Food Technology http://members.ift.org/NR/rdonlyres/E4378363-6C76-4CDE-A1BE-62B172F1BDD8/0/0208featfiber.pdf the authors note, “Heaton (1973) proposed that fiber acts as a physiological obstacle to energy intake through at least three mechanisms: 1) fiber displaces available calories and nutrients from the diet; 2) fiber increases chewing, which limits intake by promoting the secretion of saliva and gastric juice, resulting in an expansion of the stomach and increased satiety; and 3) fiber reduces the absorption efficiency of the small intestine.”
    So, at least a few scientists know that the digestive system has limited ability to transfer calories from the small intestine to the bloodstream but most ignore the effect. And all of them ignore the BHF.
    I can buy into the idea of BHF to an extent. But what about the weight loss that comes from consuming a zero-carb diet, i.e., an all-meat diet? There is no fiber in such a diet to feed the bacteria, so weight loss from that diet wouldn’t include much of a component from BHF. I guess what I’m saying is that I’m sure BHF contributes something, but not everything, towards the metabolic advantage that comes from overfeeding.

  23. Hello,
    I was wondering if you had heard of the program on BBC called Horizon?
    They recently did an episode titled ‘Why are thin people not fat?’
    You may not be able to stream the show from outside the UK, but it is available as a downloadable bitorrent.
    In any case, it was a very interesting but small scale study, which yielded some interesting outcomes regarding the physical and psychological states of some ‘naturally thin’ people here in the UK.
    Hope you get an opportunity to check it out!
    I would love to see it, but haven’t been able to do so. It’s not available here in the US.

  24. This is driving me nuts. I see no reason why calories should count on a low-carb diet, particularly a very low-carb diet. People gain weight on a high-carb diet when they develop insulin resistance and hyperinsulinemia because the insulin locks up the fat cells and the fat cells can’t release their stored energy. If you’re low-carbing, your insulin normalizes, meaning that most times of the day it’s not elevated at all. (Everyone experiences an increase in insulin levels when they think strongly about or smell food. Taubes talks about it in GCBC. But that’s the only insulin they put off if they don’t then consume glucose-forming foods, as far as anyone can tell considering the amount of study done on the issue.) If your insulin’s not elevated then why would the fat cells still be locked up?
    Seems to me that would work quite independently of how many “calories” you consume. It isn’t “calories” that set off insulin to begin with. And fat’s used for other things in addition to energy regardless of what diet you follow or which metabolic pathway you’re using.
    It’s a shame nobody does direct studies about this anymore; it’s not like they couldn’t find an ethical way to do it. (If I could work out childcare, I’d volunteer as a human guinea pig for such a study in a hot minute.) I would be curious to know whether there is as wide a variation in so-called “calorie-burning” among people on VLC diets as there is among people following something closer to SAD.
    But for my own anecdotal data, one of the times I underwent low-carbing I was well over 200 pounds (possibly close to 250, in fact–definitely over 200), at 5 ft 6 in. in height, could eat almost 3000 calories a day sometimes and still lose. Obviously it wasn’t too high in protein and I was essentially following Atkins at the time. Atkins himself documented in his book how one of his patients was eating huge amounts of beef almost daily and still dropping weight like a lead balloon. OK, he was a guy, and they lose weight faster, but I wasn’t much of a slouch myself. Got down to XL sized shorts before I gave it up for a reason I can’t even remember now.
    I believe (I’d have to read it again) Atkins thought that the cheese and nuts you mention as “caloric” causes of weight retention on LC actually stalled weight loss because they contributed to an existing systemic Candida infection. And there may be other reasons unrelated to caloric intake. They *are* higher in carbs than meat and fat are, which could be an issue in some people as well. Still, I don’t know about you, but I can’t get very far eating cheese or nuts without feeling stuffed to the gills.
    You’ve got to create a deficit to lose weight. But how that deficit is created is a tricky question. Some people who eat a lot of low-carb foods may substantially increase their metabolic rate and at the same time spontaneously become more active. Others may not, and, as a consequence, not lose. Others yet will find their hunger decreased on a low-carb diet and will eat less and create their deficit that way. People react differently, but somehow a deficit has to be created – whether from within or without – to bring about weight loss.

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