Why the first law of thermodynamics has no place in human nutrition

The first law of thermodynamics says that energy can’t be created or destroyed. Many people (wrongly) think Sir Isaac Newton worked this one out, but it seems it was more likely a Welsh lawyer (score one for the lawyers!).

It’s a law about physical forces that unifies a lot of previous theories that related to heat and mechanical energy. In the nutrition and diet industry, it usually looks more like “energy in must equal energy out” or just “the energy balance equation”. They will even sometimes do an actual equation (I guess to make it look more scientific).

Weight Gain (Energy Balance) = Energy In (Food) – Energy Out (Exercise).

The First Law has been hijacked by the nutritionista because it kinda sounds like it should apply to dieting. As a result it is used more today in human nutrition than in any other domain of human endeavour. The First Law is quoted every time you watch or read any information on diet products, exercise or weight loss programs. And the government throws it your face even more regularly than that.

We are told the only way we can lose weight is to either consume less energy (calories) or burn more energy (by exercising). Fat has almost twice the calories per gram as protein or carbohydrate. This is why fat is often the target of calorie restriction hysteria. Gram for gram you can eat almost twice as much of a carbohydrate and not unbalance your equation.

Sounds logical, right? And I guess that’s why this simple message has so much traction with advertisers.

The only problem is that it is utter nonsense.

The First Law certainly says that when we gain weight there will be an accompanying increase in the number of calories consumed (or decrease in the number burned). It is an equation and in equations each side must equal the other, but that does not necessarily mean that increased calorie consumption causes the weight gain.

It is equally logical to say that gaining weight is the driving force in the equation. In other words, weight gain causes us to consume more calories.

When a child grows they increase their body size and weight. These growth-hormone driven changes cause the child to consume more calories, not the other way around. Not even the most rabid nutritionist would suggest that feeding a 10 year old like an 18 year old would help you get past those awkward teenage years more quickly.

Growth happens because our hormone clock says it should. Calorie consumption just keeps up (so that the energy balance stays, well, … balanced). We are perfectly happy to explain the equation that way when we talk about people who grow vertically. We’re even happy to accept that pregnant women gain weight (other than the baby of course) because hormones tell their bodies to fill the baby-pantry.

Eating is the way we put on weight, it isn’t the reason we put on weight. When a car accelerates, it does so because it has access to more petrol. The petrol doesn’t cause the acceleration, but it does enable it.

But for some reason when Norm grows horizontally, causation is magically reversed. Nutritionists lurch from physics into psychiatry and the cause suddenly becomes greed or sloth (or both).

Just like height gain, weight gain is caused by hormones, but this time it is hormonal dys-function. The fructose half of sugar causes us to become resistant to our main appetite suppression hormones (insulin and leptin). When this happens our appetite is not shut-down when it should be and we just keep eating. And just like a Toyota with a stuck accelerator, our weight accelerates out of control.

Once we understand that weight gain is caused by hormonal dysfunction (a stuck accelerator) many (previously) mysterious things become clear.

A diet that asks you to consume less calories by exercising willpower is doomed to failure. Imagine how successful you’d be if you asked a child to exercise some willpower and stop growing. Fighting hormones with willpower is about as effective as paddling upstream with a barbed-wire paddle. Perhaps this is why the best indicator that you will be heavier in five years is being on a diet now.

Lap band surgery restricts the fuel supply without the need for willpower. It’s like clamping a fuel line in the car analogy. Less fuel gets through for a given squeeze of the accelerator. But our bodies are nothing if not adaptive, so they just ramp up the demand for calories (they push harder and longer on the accelerator). Perhaps this is why a lap-band driven ‘remission’ lasts only 10 years (at best).

Exercise burns so few calories that very few people can commit the time (or willpower) required for it to seriously affect energy balance. But even if they could, using more energy just increases the demand for energy (any gym junkie could tell you that). Lumberjacks eat more than office workers because they exercise more.

Diets, surgery and exercise do not affect the cause of weight gain (which is the hormonal dysfunction created by fructose) and so, they don’t work. Yet they remain the only targets of the billions spent ‘combating’ obesity in this country. All because the nutritionista hold true to a law of physics which has been misapplied to nutrition for the past 60 years.

When nutritionists first started guessing what made us fat, only one of the four major appetite hormones had been discovered. Then, it was (almost) acceptable to squeeze the square peg of a physics law into the round hole of human biochemistry. But those days are long gone and so too should be our tolerance for that kind of guesswork.

Many careers have been built on propagating this nonsense and there are many who will fight hard to protect it. But that should not be an excuse for inaction in the face of a human health disaster of truly epic proportions (pun intended).

Image courtesy of Ambro / FreeDigitalPhotos.net

Join the discussion 60 Comments

  • Well written, we can only hope people will come to understand this concept in the next 50 years…sigh

  • susiecol says:

    It’s true – I do a lot of exericse and I eat a lot, there is no way I could do it if I didnt chow down big time on those days of high intensity .. I just hadn’t thought much about it until now. Thanks for great article.

  • Harry says:

    David says:

    “Just like height gain, weight gain is caused by hormones, but this time it is hormonal dys-function. The fructose half of sugar causes us to become resistant to our main appetite suppression hormones (insulin and leptin). When this happens our appetite is not shut-down when it should be and we just keep eating. ”


    “Diets, surgery and exercise do not affect the cause of weight gain (which is the hormonal dysfunction created by fructose) and so, they don’t work”

    Ok, here’s the problem…the word “cause” is doing a lot of work here, and not all of it justified by the evidence.

    Clearly , the standard Western diet’s fructose component is not a sufficient condition to cause obesity – if it were, ALL consumers of it would be obese.

    Clearly, it is also not a necessary condition for obesity, as there are obese people who do not eat fructose.

    So, from the outset, we’re reduced to arguing that it may be a contributory casue (i.e. a variable that influences things but does not constitute either a necessary or sufficient condition.

    Contrast this with the energy balance theory (i.e. more energy in than energy out causes mass gain). Clearly, this is articulating a sufficient and necessary cause (the strongest of all causal claims).

    Now, as per David’s article,the equation is of course only trivially true, in that it doesn’t explain what might encourage human beings to habitually over-consume and/or under-expend energy. But the fact remains, if you’re gonna talk of “causes”, then it’s energy balance that is the properly identified causal agent here.

    Correctly viewed, the debate about fructose isn’t about what causes obesity; it’s about what encourages over-eating ! In practice, this will often amount to the same thing, but not always (e.g. athletes, over-exercisers, body-composition obsessives etc.).

    It is possible to eat heaps of fructose and still be thin (but it is rare). So the “causes obesity” claim constitutes a bridge too far. The much more robust claim is that fructose (more than other food-stuffs) encourages over-eating, which in turn contributes strongly to obesity.

    By all means, let’s avoid over-consuming the stuff. But let’s also keep a grip on the scope of the claims being made here – credibility once lost is almost impossible to recover !

    Cheers, and thanks for a very interesting debate.

  • Harry you said: “It is possible to eat heaps of fructose and still be thin (but it is rare)”

    The only people I can think of who would fall into this class would be folks suffering from fructose intolerance or people with permanently depleted glycogen stores (such as marathon runners).

    Did you have some others in mind?

  • Harry says:

    Before answering, let me make something very clear…I think that chronically eating large amounts of fructose is an exceedingly poor diet choice for 100% of people (including endurance athletes). The inflammatory, immunosuppressive, and glycemic effects of diets high in fructose are incontrovertibly b-a-d.

    Ok, cool. Now to the contestable part.

    David, as I’m sure you know, the conventional diet wisdom surrounding exercising athletes is to stuff them full of simple- sugared sports drinks (with added ‘electrolytes’ no less!) pre,post and during bouts of intense exercise. Of course, ‘recovery’ meals typically include bananas, mashed up with oats and maltodextrin shakes to ‘spike’ insulin etc. etc.

    Clearly, it’s not just marathon runners that eat this way – it’s sports people in general. And, guess what – they stay lean, even in the face of this fructose assault. Now, for energy balance theorists, the explanation for this is dead simple – the copious exercise compensates for the copious calorie intake. However, for the fructose-obesity causality theory, the existence of such fructose-chugging athletes is quite simply, impossible (depending on how seriously you treat Popper and falsification!).

    Either fructose ’causes’ obesity (in which case exercise or lack thereof is irrelevant, just like exercise is irrelevant to suffering radiation sickness) or it doesn’t cause obesity, and something else (like energy balance) is the causal agent.

    If the latter is true, then the role of high fructose consumption, whilst not a cause, is that of a contributing variable. To wit, high fructose consumption encourages appetite, which in turn encourages over-eating, which in turn encourages a positive energy balance, which in turn CAUSES obesity.

    For practical purposes, we can, should, and must encourage people to avoid too much fructose. But not because it causes obesity, but because of what it does to appetite.

    The bottom line is that there is no irresistible biological mechanism linking fructose to obesity (lean sugar-fueled athletes and teens prove this in spades). The link is not physiological, it is psychological. Fructose makes getting fat easy – not biologically inevitable. Contributing variable, NOT cause.


    P.S. Stay away from too much sugar folks. It’ll make you hungry.

  • mick says:

    people talking about energy balance seem to assume that all the food you eat must be burned as energy. Carbs are the only nutrients that are used this way. Proteins and fats have more than one purpose.

  • Al Gallo says:

    Instead of what Harry suggests: ‘stay away from too much sugar folks’, I would propose stay away from sugar full stop.

    David has been very clear in his campaign pointing to fructose added via sugar to all sorts of commercially available eating stuff as causing a tragedy, and has provided impressive leads to scientific evidence in this regard. If we talk about athletes eating bananas or any other fruit we must remember that by doing this they ingest fibre as well.

    When I was a fruitarian I enjoyed a rather light weight and the levels of energy necessary to deal with a physically demanding blue-collar job. I abandoned the exclusively fruitarian diet and adopted an omnivore one when a blood test confirmed my suspicions that the level of vitamin B12 could dangerously fall. The idea of trying to stay away from too much sugar, like trying to stay away from too much food in general as a cold turkey solution, may work well only to mask the very real problem faced by our community.

    I remember well when a peddler of profitable medical scientism loudly and boorishly voiced the macho willpower ‘eat less’ proposition after David delivered a thorough presentation of his book ‘Sweet Poison’ in Brisbane.

  • Harry says:

    Al Gallo,

    Some people may well do better in avoiding sugars altogether (given the impact it has on limbic hunger). But, I think the all-or-nothing mentality is generally unhelpful for diet compliance, as it tends to lead to bingeing.

    Small and/or infrequent amounts of sugar are well-tolerated by most individuals, and certainly do not adversely impact on body composition. My clients (I run a body composition consultancy) do better when they are allowed the odd sugary indulgence (usually one cheat meal per week) rather than being forbidden to every again eat a sweet ! By the way, I consistently bring men down to sub 8%bf and women to sub 12%bf using this approach (very low sugar 95% of the time, with occasional cheats for psychological relief). The key is to use protein (and to a lesser extent fats) to provide satiety, and thus diet compliance. It’s not so much about avoiding fructose at all costs, but more about encouraging satiety over the long-term.

    Having said that, I certainly don’t think you’ll be doing yourself any damage by avoiding all sugar. If you can handle it psychologically, then it’s a perfectly serviceable physiological solution. It’s just not a necessary one.


  • Belinda says:

    David has done a good job of summarising this story, which I believe is absolutely true. But will all due respect, Gary Taubes does a great job in Good Calories, Bad Calories, of demolishing the whole law-of-thermodynamics argument. Worth a read (and I assume David has) for anyone who wants the full, scientific story.

  • Harry says:

    Belinda says:

    “Gary Taubes does a great job…of demolishing the whole law-of-thermodynamics argument”

    Yes and no. Taubes suggests that chronic hyper-insulinemia brought about by chronic carbohydrate consumption is responsible for the rise in Type II Diabeters and CVD (I’ve read the whole book; very well written). He also (and this is where Belinda’s comment kicks in) suggests that the 1st law doesn’t adequately EXPLAIN why people gain weight. This is not even close to arguing that the 1st law is “demolished” ! He simply reverses the common interpretation that attends the equation (we eat too much, therefore we get fat) to offer a novel reading of the same event (we get fat, therefore we eat too much). All this is very interesting and thought-provoking…but here’s the problem:

    The fact of the matter is, RCTs consistently show that, under calorie-matched and protein-matched conditions, body weight flux is entirely a function of energy balance, not of macro-nutrient composition. In other words, so long as your calories are lower than your expended energy, you WILL lose mass, irrespective of whether you were eating predominantly meat or bran muffins.

    RCTs also show that,under ad libitum conditions, restricting carbs will lead to spontaneously lower calorie intake, due to satiety and appetite suppression.

    So, yes, restricting carbs will “cause” you to lose weight, if by cause you simply mean that it will encourage you to spontaneously consume less calories. But no, restricting carbs will not, of itself cause weight loss in the absence of a sufficient energy deficit. Believe it or not, you can and will get fat by eating four sides of bacon and three dozen eggs per day, even without the addition of sugar, fructose, or any other fingered villain.

    And, you will lose weight by restricting calories below energy balance levels, even if you’re just eating fruit all day long. Sure, you’ll feel hungry all the time (this is why I don’t recommend high carb diets; it’s a compliance issue), but you will lose weight.

    Taubes has not demolished the 1st law, he’s simply refocussed it to look at psychology (why we eat too much) as opposed to physics (that we eat too much).

    Again, let’s hang on to our hats here guys; low carb diets are a good technique for many people, but they do not contravene thermodynamics.


  • mick says:

    I was under the impression that when there is a caloric deficit, your body slows it’s metabolism, thus making weight loss harder.

  • Harry says:

    mick, you’re quite correct.

    Weight loss does become more difficult as you approach a lean body composition; which is unsurprising when viewed from an evolutionary perspective.

    This isn’t something to be worried about though – metabolic slow-down effectively means that your body becomes more efficient with your food intake; which means you don’t need to eat as much or as often to sustain the same amount of activity. This means less oxidative stress, less dietary-induced inflammation, less ‘metabolic churn’; all very good things if you want to live a long life.

    Sure, it also means you can’t pig out and stay thin, but that’s always struck me as a strange desire in any case (akin to wanting your cake and eating it too).

    Having said all that, once again, restriction of calories brought about by fructose-restriction or by restricting other foods makes no difference to metabolic slow-down. It’s a response to weight loss and energy deficit, not to any particular macro-nutrient profile.

  • Russell says:

    When a child grows they increase their body size and weight. These growth-hormone driven changes cause the child to consume more calories, not the other way around. Not even the most rabid nutritionist would suggest that feeding a 10 year old like an 18 year old would help you get past those awkward teenage years more quickly.
    I agree with you on this part, except now a lot of kids growing up is the hormones they add to our food unfortunately.

  • Harry says:

    Russell says

    “When a child grows they increase their body size and weight. These growth-hormone driven changes cause the child to consume more calories, not the other way around”

    Russell, I wish we lived in a world where this was true (where hormone-induced urges to eat actually CAUSED the consumption of excess calories). I wish we lived in that world, because it would be a world without child hunger and malnutrition.

    You see Russell, the fact that there ARE millions of children around the world who go hungry simply proves my point in spades. Their hormone-induced disposition to eat excess calories doesn’t CAUSE them to eat the excess calories (for that, the excess calories would need to be accessible to them). No, it merely disposes them to eat excess calories.

    And so, we see, once again, that the disposition to eat in excess (whether brought about by growth hormones or by insulin, or by excessive fructose consumption etc.) is not the same thing as the CAUSE of obesity. It is simply a contributory cause (see above posts for explanation of categories of causation).

    Positive energy balance CAUSES obesity ; all the other stuff merely constitute the conditions under which achieving a positive energy balance becomes easier (i.e. the so-called ‘obesogenic environment’).

    People really should stop playing fast and loose with the word ’cause’.


  • John says:

    I must say, I am disappointed.

    Essentially, this is what it boils down to:

    – Fructose, like foosball, is the debill.
    – Fructose makes you fat, no matter what. Excessive consumption of calories isn’t the problem. Fructose is. Excess calories is just a symptom.
    – You don’t get fat because you eat too much. Fructose makes you fat, and then you eat excess calories because you’re fat.
    – With limited exceptions, the entire food industry is the debill. Secretly trying to make your body fat, so you will eat more. They do this by putting fructose in everything, which is addictive and which causes your body to make you fat, causing you to consume more calories, which is what the conspirators want.

    It logically follows that it’s just a massive coincidence that all obese people consume excess calories – and that all people losing weight have a dietary calorie deficit.

    Now, if a glass of fruit juice a day will make you gain 2.5kg in a year – simply because the juice contains fructose – then what are the consequences of ingesting the same amount of calories in a different form? How about glucose?

    I would be very interested to hear that I’m wrong, and why. If fructose is genuinely bad for me, and not simply being painted as a boogeyman by an unsubstantiated hypothetical framework, then it is important information and I would be grateful for being steered in the right direction.

    Forum participant/contributor Harry has pretty much elucidated my precise objection to the major claims made. In my opinion David’s responses to them have been inadequate and Harry’s subsequent replies devastating.

    For my money, lack of citation means lack of evidence. Unsupported statements are amateurish/shoddy/a complete waste of time. If clinical trials – reputable ones conducted properly – exist and which back up David’s hypotheses, they are not cited. If the evidence does exist, it should be cited. If not, the claims are guesses. We have here either a problem with David’s academic rigour or his claims themselves. A good academic would provide sufficient evidence to put his claims beyond reproach; a bad academic should not be listened to in the first place.

  • Al Gallo says:

    John suggests that there may be ‘a problem with David’s academic rigour’.
    David has demonstrated a rigorous approach by providing abundant evidence in his book, and his articles show links to all sources relevant to the subject.
    If John is REALLY interested to listen to an academic rigorously dealing with the subject of fructose, I recommend, for a start, the following link:
    Warm regards.

  • Al Gallo says:

    The link I provided got unfortunately fragmented.

    the article I suggested.

    My apologies.

  • Harry says:

    Al, you said,

    “When I was a fruitarian I enjoyed a rather light weight”

    Now check out this sequence:

    1) Fructose consumption causes obesity
    2) I was a fruitarian
    3) The calories from fruit are from fructose
    4) I was a rather light weight

    See any problems Al?

  • Al Gallo says:

    I don’t see any problems Harry, and I will explain why.
    First of all, a fruitarian diet has been defined in different ways, but generally includes tomatoes, berries, which are botanically fruits, nuts, seeds, and oily fruits such as coconuts and avocadoes.

    As I’m not sure if you’ve read David’s ‘Sweet Poison’, I’ll transcribe a fragment from page 76:

    When we eat carbohydrates, proteins and fat, insulin and CCK tell us when to stop eating, and insulin and PFK-1 control the use of the glucose. There are no equivalent controls for fructose. When the only fructose in our diet was in ripe fruit, this didn’t matter much. We have enough fructose sensors in our pancreas to trigger an insulin response in the quantities found in a few pieces of fruit. It is only when we over-consume fructose that the ‘loop-hole’ in our appetite-control mechanism opens up. In a modern diet, where most food is now flavoured with fructose compounds (like sugar and high-fructose corn syrup), this is a recipe for obesity and much worse.

    According to my experience in fruitarianism, I would add that more than a few pieces of fruit can be eaten without risking obesity.

  • Harry says:


    You entirely missed my point.

    So I’ll make it super explicit this time…

    If a good portion of your calories came from fructose when you were a fruitarian, and you did NOT become obese, then this falsifies David’s theory (i.e. that eating fructose CAUSES obesity).

    Either fructose consumption CAUSES obesity, in which case all fruitarians would be obese, or it does not.

    Which is it?

  • Al Gallo says:

    Dear Harry,

    Fructose causes obesity and David has been very explicit describing the context in which it does.
    The quotation I included previously says it all; it is easy to understand and describes in a nutshell what his position in the fructose subject is.
    If you’ve got further questions I suggest you email David directly.

  • Harry says:


    The passage you quoted is probably the least controversial element of David’s stance (i.e. that too much fructose is bad for you). Pretty much everyone, including me, agrees that chugging down 200gms worth of fructose/day is going to mess you up, and the studies show that very high levels of fructose (>200gms/day) do impair satiety signals.

    However, that is worlds away from the claim that ‘fructose causes obesity’. In smaller, more typical doses (mean US consumption in 2008 was 54.7g/day), studies do not show any of the health impacts that are elicited at higher doses.

    This study…


    …shows that mean fructose consumption has gone up by a mere 17.7g/day since 1977 – that’s the amount in one large apple. Are you seriously trying to pin the obesity epidemic on an apple a day?

    Meanwhile, average energy consumption has gone up 20% between 1982 and 2000:


    Again, heaps of fructose will screw you up (as will heaps of glucose). But, just as normal amounts of fructose (37g/day in 1977) didn’t make us all fat then, a smidgeon more (54.7g/day in 2008) isn’t making us all fat now.

    Let’s not miss the forest for the trees people…on the one hand, an extra 20% of calories, day in day out. On the other hand, one extra apple.

  • lark says:

    I’m really glad you’re here to provide authority and real expertise, while articulating the same objections I’ve had to David’s viewpoint. I can say it, but he’ll just blow me off.
    I’ve found a very lowfat, very low-fructose, almost entirely vegan diet to be great for keeping me slender. I am NOT hungry all the time! It’s a McDougall style diet. And I exercise mildly. The key is to eat a lot of vegetables and whole foods. Potatoes were tops in the “satiety index”, which was created to measure how much a certain amount of calories filled people up. I do not crave fat. It takes a while getting used to this diet, you’d have to phase it in gradually, because people get used to fat as a satiety signal when they eat a lot of fat.
    Additionally, this kind of diet is the only one that has been proven to actually reverse heart disease! It actually reduces the blockages in people’s arteries.
    This was very impressive to me. I guessed that if the Ornish/Mcdougall type diet is helping circulation in arteries near the heart, it does so in other arteries in the body as well: perhaps keeping good blood supply to one’s brain and keeping the brain healthier, for example. Research I’ve seen has tended to confirm that guess.
    Also people who are obese eat higher-fat diets on average than those who aren’t.
    It would be very difficult to get overweight, eating the way I do.
    The major disadvantage of this way of eating is that it doesn’t fit in socially. Eating is a social ritual. People bond by eating the same things. One has to be willing to be different from other people, and work out ways to deal with the social consequences – like, socializing with people outside of an eating framework, dealing with people who want to give you gifts of food, etc. It wouldn’t work to just eat the same as others occasionally, because suddenly changing and going for fatty food feels gross, might cause indigestion, etc.
    But to me the possible advantages, like staying very healthy into old age, seem to outweigh the disadvantages.
    Also, it would be interesting to know whether eating tons of fruit and exercising a lot is healthy. People who do this stay slim, but do they escape the other bad consequences of fructose, like high AGE’s, etc.? Probably not.
    They think it’s fine, because they stay slim and feel good. And all the sweet fruits are part of why raw vegans enjoy their diet.

  • paul says:

    It’s really good to know more about the law of thermodynamics and why it has no place in human nutrition. Thanks a lot for sharing.

    Vitamins Canada

  • nads says:

    For the past 5 years I’ve been counting calories and have had my weight under control at quite a low body fat percentage (23% for a woman is pretty good). I was a sugarholic and as long as I ate basic food groups I’d fill up the rest of my calories on sugar. Even the food groups would be full of things like cereal containing sugar.

    Anyway, what I wanted to say was that I didn’t gain weight, and ate approx 2300 calories (quite good for a 40 something woman of 53kg). My point is, the sugar didn’t make me put on weight. BUT I was always hungry. As a semi-reformed binge eater (and I mean real binge eating, like bulaemia without the vomitting) I found it increasingly hard to keep my eating urges under control, and lately indulged more and more to the point of weight gain. ONLY because I ate lots of calories.

    So since hearing David talk and subsequently reading the book, the lightbulb went on in my head. I realised why I always felt the need to overeat. My brain and body wasn’t registering all those sugar calories!!! So for the first time in my memory I feel full and satisfied during a meal. I’ve been eating full fat and almost no fructose.

    So in a way, I do agree with calories in and calories out (although didn’t David say that it’s different for pre-menopausal women due to the protective effects of oestrogen?) but that’s all very well if you are restricting and calorie counting. It’s totally different if you are eating what your brain tells you it wants!!!

  • nads says:

    Regarding my previous post, I forgot to say that I had lost almost 30kg but calorie counting five years ago.

  • Margaretrc says:

    @Harry, I think the jury is still out as to what causes the hormonal dysfunction–it’s possible excess fructose contributes, but there may be other thing. However, I think it’s entirely valid to say, as David does, that, just like a child’s growth hormones cause the child to over eat (not the other way around), an overweight person’s hormonal dysfunction is what is causing the weight gain and the over eating, not the other way around. So throwing out fructose as a cause of hormonal dysfunction doesn’t invalidate the thesis that it is hormonal dysfunction causing the weight gain.

  • Harry says:

    Way to resurrect an old thread! Kudos.

    Yes, there may be (in fact I would say it’s nigh on inevitable) a hormonal disregulation involved in many people’s overeating habit, but this is not the ’cause’ of overeating. If it were, then everyone with hormonal disregulation would be fat, even in conditions where overeating is discouraged by the food environment. There are sufficient falsifiers to this view to put it to bed (e.g. France, Japan).

    Hormones and genetic predispositions may encourage overeating in the context of an obesogenic food environment, for sure. But it’s the permissive food environment that’s the driver here (and that’s what’s changed in the last 30 years).


  • Kirk Bloomer says:

    I enjoyed the article. My experience has been similar. If I exercise while keto-adapted I’m NOT hungry, same exercise while burning sugar and I’m ravenous after (crave carbs). Funny how people always wanna shoot this idea down without trying it. I guess I would too if I hadn’t. If it was a pill it would win the Nobel prize. (I’m keto-adapted for a year now)

  • Nicholas Tomlin says:


    Please explain your version of ‘keto-adapted’.. I assume you mean ‘ketotic’ in this?
    What do you do to be ‘keto-adapted’?

  • PhilT says:

    Energy out = Energy in – accumulation

    Exhaled gases + urine + faeces + heat loss to ambient = Energy from food – energy accumulated in body fat / LBM

    or Food you have to eat = Exhaled gases + urine + faeces + heat loss + energy stored as fat

    the concept is valid, you just have to arrange it logically.

    Personally I find substrate balances on carbohydrate and fat can lead to clearer thinking.

  • Leah says:

    Harry, you speak more sense than pretty much anyone I’ve ever read on this website

  • Tania says:

    Wow. What an awesome debate. Thanks Harry

  • Greg says:

    I agree! I read Gary Taubes’ “Why we get fat and what to do about it” (published 2011) which appear to have similar / updated material to “Good Calories, Bad Calories). Very stimulating and highly informative!

  • vlad says:

    LOL wow, this article could NOT be more wrong. Not everyone who is fat has a hormonal dysfunction hahahahh

  • Wow – this thread and the subsequent comments are some of the most interesting points I’ve read in a long time. I’m currently 3 months in to no sugar having read David’s book which just resonated with me, but I’m also currently studying for my Level 3 Personal Training and Advanced Nutrition qualifications which have a very different stance on what we should be consuming to lose weight / gain muscle. To put it simply – I am so confused! I am happily sugar free (bar low sugar fruits) and wouldn’t consider going back to eating fructose in the near future, BUT I do totally believe that calories in vs. calories out is the key to weight loss. Fats don’t sit well with me so I’m never going to be skinny/strong from eating a very low carb / high fat diet so I am still on the pursuit for the perfect combination of macros. Great insights here from Harry and others. Thank you.

    Here is the blog post I wrote about David’s book, if you are interested. It’s not science based at all, more of a generalist viewpoint for sugar free newbies. http://nowforthelastten.com/i-quit-sugar-part-one/

  • P.S. I’ve lost around 10lbs since I quit fructose, but I don’t think this is the sole reason. I’ve also cut down on booze and upped my exercise in recent months.

  • Vinay Datar says:

    Harry, Excellent commentary! I understand you are a trainer. Please send me your contact information. vinaydatar@yahoo.com

  • León says:

    “The petrol doesn’t cause the acceleration, but it does enable it.”
    Since when enabling is not causing?

  • Matty says:

    Harry is beyond spot on. This is the difference between someone(david) that is spouting hypothetical overstatements and someone that has obviously had hundreds of real world experiences in order to test his views on nutrition with client. I don’t completely disagree with some of David’s viewpoints but if his premise that fructose MAKES you fat and has nothing to do with the law of thermodynamics, he fails miserably and loses all credibility. As Harry stated I would love to see David eat a total of 5,000 calories of bacon and eggs with whatever else he would like and just see what happens. Actually I encourage anyone that has doubt to do the same and I promise you will be in for a surprise. I believe Andre Perlot tracks this whole theory on YouTube and has to quit because he got so fat.

  • David Gillespie says:

    You’re in luck Matty the experiment you propose has been done. Sam ate a 5,000 calorie high fat diet for 21 days. This was the result “If a calorie is just a calorie when it comes to eating food, over the 21 days I should have put on 7.3kg ending up at 92.9kg from my starting weight of 85.6kg. However, after a 56,654 calorie surplus over the 21 days I ended up putting on 1.3kg ending up at 86.9kg, a relatively large discrepancy to say the least to the tune of 6kg. I also measured my waist which started off at 79.5cm and I ended up at 3cm less at 76.5cm. Not exactly congruent with the linear weight gain and waist increase the calorie formula shows in my results graph and photos below.” http://live.smashthefat.com/why-i-didnt-get-fat/

  • Chris says:

    The difference between fructose/glucose is very simple in terms of human storage mechanisms.
    The only correlation between people getting fat because of fruit would be the fact that fructose is stored/metabolized in the liver. when the Liver is full any caloric surplus will cause weight/fat gain in a human. This doesn’t mean its a causal factor though. the simple fact is you cannot blame one section of macronutrients entirely in terms of fat gain. this article is removing one stigma and replacing it with another.

    If humans moved more,played more and ate less calorically dense garbage they would be leaner. this is obvious when you look at the blue zones. Hormonal issues are also a very prevalent cause but just like any other fitness fad diet or aticle you just chose to demonise one section that meets your agenda. How about the correlation of cortisol and fat storage, this can be caused merely by having a shitty job that you hate.. you know like 95% of the average human slave??

  • Kelly says:

    It was good reading the comments, but all I can think about now is eating a Pavlova

  • AJ says:

    This is brilliant. Very good points

  • Kelly says:

    Complete nonsense. I can calculate and accurately predict my or anyone else’s fat loss or gain simply by counting the amount of calories consumed based on height, weight, age, gender, and activity level each day. Body buliders and other athletes have been doing this for decades. It’s nothing new. Energy Balance Equation is the determine factor in loss or gain. You don’t get fat by eating hormones. You get fat by consuming more energy than your body uses for whatever purpose over a period of time. If this was not true, we would stay the same weight constantly no matter how much or how little we ate. Now, reasons why you consume more calories than you need in a day can vary. But there’s only one reason you gain or lose body mass in the form of muscle or fat and that is over or under consumption of calories over time. Period, no ifs, ands, or buts.

  • Dale says:

    Your article is based on a misunderstanding of the first law of thermodynamics, on your part, not the nutritionists. The law present by the nutritionists etc you mention is not equivalent to the equation you present: “Weight Gain (Energy Balance) = Energy In (Food) – Energy Out (Exercise)”.

    ‘Exercise’ is not equal to ‘energy out’, ‘exercise’ is INCLUDED in ‘energy out’. The fact that someone presents a flawed version of the law does not mean that the law is wrong and does not mean it doesn’t apply in nutrition.

    Is a a law , that means it applies everywhere.

  • David says:

    The principle derived from the law of thermodynamics is that energy, and therefore, matter cannot be created or destroyed.

    Hence, fat cells cannot be created nor enlarged with additional lipids from nothing, and the energy necessary to sustain a body cannot be derived from nothing.

    I cannot tell you how many people I have met that literally believe that it is not possible for thier particular body to lose weight… period. The notion defies the physics and any science regarding thermodynamics.

    Now, weight loss may involve many factors such as differing metabolic rates, various gut microbes, duration and intensity of exercise, etc. However, boiled down… If you eat less than you burn you will lose weight over time. No disrespect intended but there were no fat people in Auschwitz

  • Ben says:

    Look as the PhD in physics on the forum I have to say that the article is right. The first law is a tautology. It is always true but thats all it tells you, any weight gain or loss has an equal difference in energy entering and leaving the system. But the article is completely correct that there is no causality in that equation. The best analogy is a crowded room, if I asked why the room got more crowded it is completely true that it because more people entered than left. That’s true but not an underlying cause. This analogy is a logical equivalent to CICO.

  • Razwell says:

    Energy is NOT stuff at all. Energy is ONLY A CONCEPT, A PROPERTY. Calories CANNOT AND DO NOT EVER turn or morph into MATTER ATOMS-BODILY TISSUE. Concepts do not turn into real objects.

    MATTER IS STUFF. ENERGY IS A CONCEPT. They are as DIFFERENT as heaven and giraffes.

  • Razwell says:

    And those people are correct. The body can exert involuntary control over body fatness. SROP abusing physics. STOP abusing energy. NO caoories EVER become body fat tissue. Fat tissue is MATTER. Energy is NOT itself anything.

    Energy isma NUMBER, THIS NUMBER-MATHEMATICAL ABSTRACTION does not change after Nature goes through its manifold changes. That is ALL conservation of energy means.

    Energy IS NIT EVEN CINSERVED ON A COSMIC SCAKE-ONLY LOCALLY. Sean Carroll has an excellent article about How energy is NOT conserved in General Relativity. We ALREADY live in amuniverse where energy is NOT conserved ON A GLOBAL SCALE……

    THE body can do things with breathing rate to exert control. Carbon ATOM FLOW is the mechanism. STOP misusing conservation laws. Obesity is fat tissue which is MATTER. MATTER IS NOT CONSERVED.

    Stop abusing physics to blame obese people……

  • Razwell says:

    Our “laws” are NOT mandates imposed upon nature or universe. They are OUR BEST GUESSES.

    We already live in a universe where energy is NOT conserved as Sean Carroll points out. Onoy LOCALLY is energy xonserved.COSMICALLY IT IS NOT-EXPANDING UNIBERSE IS AN EXAMPLE. Energy is ONLY A NUMBER, A CONCEPT, NOT AT ALL STUFF.

    Fat tissue is MATTER-ATOMS. SROO ABUSING sciende and ohysics to bkame obese peoole. Pro ohysicusts STRESS obesity is NOT A PHYSICSMISSUE, RATHER BIOCHEMICAL AND GENETIC

  • Razwell says:

    Incorrect. Energy is ONLY A CONCEPT. CALORIES CANNOT AND SO NOT EVER morph into matter. Calories are nit AT ALL STUFF-NOT ANYTHING themsekves.

    Atoms are what add fat tissue. The fitness industry ABUSES physics. Energy, a NUMBER, NOT A THING, IS XINSERVED LOCALLY ONLY. IT IS JUST SOME WEIRD JATH FACT that there isma NUMBER that dies notmchange after nature goes through its manifild changes.


  • Razwell says:

    Fat tissue is MATT3R, STUFF. ENERGY IS A CONCEPT ONLY. Fat tisue , ATOMS CANNOT be burned away or burned off. The entire fitness industry is physkcs illiterate.

    Caoories CANNOT AND DO NKT turn i to matter-atoms-fat tissue

  • Eric says:

    What you fundamentally fail to understand is that the First Law of Thermodynamics is driver-agnostic. In other words, it does not matter which variable of the system you are controlling. If you are controlling calories in (willpower based diet), calories out (natural child growth, exercise-based diet), or whatever, it doesn’t matter. The balance of the equation holds, because it is the Law of Thermodynamics, not the “Suggestion”of Thermodynamics.

    Energy consumed and processed in excess of that which is expended will be stored. Whether it is stored as fat or as muscle or as other tissue is dependent upon other variables, but suffice it to say, weight will increase because of the mass retained from food in order to create the storage medium.

    Energy expended in excess of that which is consumed necessarily leads to the body retrieving stored energy from somewhere. Whether it is retrieved from fat or from muscle or from other tissue is dependent upon other variables, but suffice it to say, weight will decrease because of the storage medium being broken down to recover its stored energy, converted into waste product, and expelled.

    There is no way around this. There are two ways to look at it.

    1) If you are going to expend the energy, you had better consume it
    2) If you are going to consume the energy, you had better expend it

    Failing either of these, your weight will change. The First Law has every place in human nutrition, but not in a vacuum. Other variables must be considered because the one thing that we do have some control over is how the First Law is applied to human physiology. Denying the First Law is the first step in making excuses, and you should stop.

  • Neil Brooks says:


    Great response…

  • KEK says:

    Physics is not something you arbitrarily choose to apply or not, it applies to everything.

    No food intake = no resource to create additional body weight

  • bob jenkins says:

    This guy is an idiot. Energy absorbed, not ingested vs energy burned equals weight loss, homeostasis or weight gain, it cannot be refuted. You cannot gain weight without a caloric surplus, impossible. Sans water.

  • Noz says:

    The diet industry are desperate to show it’s not down to calories so they can push idiot diets.

    Facts are that food taken I to the body has a limited number of fates: it gets broken down and used as energy with the metabolites being excreted or it gets added to the body as fat, muscle or other tissues.

    Sure foods have varying thermogenic effects and doing exercise can lead to foods being laid down as muscle. But that’s it. No amount of harping on about hormones etc can change this. Eat too much, you get fat. And the laws of thermodynamics very much apply. You just need to apply them to the whole picture including thermogenic effects of food (which is still “calories out”).

  • Dee says:

    Great post, and I’m inclined to believe it… but I’m wondering where the studies are to back this up?

  • David Gillespie says:

    Linked in the post Dee

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