Maintenance Phase Reality Check: "The Trouble With Calories"
Before digging into what is a really sensitive, nuanced, and stressful topic, we need to state a few things up front:
Fat-phobia is rampant, especially in the medical world, and causes significant mental and physical harm. Being fat is not a moral failing. Fat people should not be treated differently than “straight-sized” people.
Everyone has absolute autonomy over their body and the choices they make. The intent of this writeup is not to convince anyone to do anything.
Understanding energy balance and the scientific consensus around metabolism is not incompatible with believing points 1 and 2. We can stay grounded in science and fight to destigmatize fatness at the same time.
The goal of this discussion is to highlight the scientific misunderstandings that Maintenance Phase (MP) falls prey to. We need compassionate, reputable, knowledgeable voices advocating for fat acceptance, and while MP has compassion for the topic in spades, they are not able to accurately convey scientific reality.
This post will get quite into the weeds, so here is a summary of the biggest issues:
Aubrey and Michael market themselves as knowledgeable enough to “debunk” calories, while showcasing a significant misunderstanding of how metabolism works.
Aubrey and Michael are not fully reading the papers they cite and not pursuing an understanding of the body of work of researchers that they cite in their show notes. They often take quotes out of context, and in many cases the next paragraph of their chosen source fully contradicts the point they are trying to support. Drs Kevin Hall and Marion Nestle, two scientists they quote in this article, are on record in multiple places explaining exactly how calories work, why they're important, and explicitly stating that the laws of physics (thermodynamics) are foundational to energy balance and fat gain/loss. Why do Aubrey and Michael quote these sources which fully contradict the argument they make in this episode (namely: thermodynamics aren't relevant, calories have been debunked, and “calories in, calories out” is useless)? We have no idea. But we do think the hosts would not be so confused about calories if they read Marion Nestle’s book or the papers they cited.
An accurate summary of the knowledge around calories is the following:
Energy balance, in the form of energy (calories) ingested vs energy (calories) expended, dictates body fat gain or loss.
There are many factors that impact both energy ingested and energy expended.
We do not need to deny and misrepresent scientific reality in order to pursue weight neutral care and respect. Yes we understand metabolism, yes calories are real, no being fat is not a moral failing or justification for poor treatment.
With that said, let's dive in to “The Trouble With Calories”.
It is somewhat unclear what the thesis of this episode is (as is evident by the vague title). Similar to the “Is Being Fat Bad For You?” episode, this episode doesn’t actually speak to the title. What this episode DOES contain is some confusing non-scientific discussion of calories and some misrepresentation of science. It is worth noting that Aubrey and Michael contradict themselves multiple times in this episode. For example, Michael says that “calories in, calories” out is so obvious as to not be useful, then says it doesn’t matter if it’s true, and then spends much of the podcast saying that it’s NOT true and that it has been thoroughly disproven (which it has not). This episode, with an alternative title and an expert guest host, could have been a really great opportunity to review the science on metabolism and the nuances of the energy balance model (i.e., “calories in, calories out”). The thesis should be a line that Aubrey says at the end, “Oh, shit, calories are not as straightforward as we thought they were." (“We” being non-scientists, because the scientific experts are WELL aware of how complicated this is and have been since the very early days of studying human metabolism.) Instead, this episode presents a lot of misinformation and pivots from topic to topic, all surface level, and none of which is particularly helpful for better understanding metabolism. So, rather than take it point by point, as done previously, I think it makes most sense to break it down and address the three main topics that this episode seems to focus on:
1) What is a calorie? Also, the first law of thermodynamics.
The podcast begins with an incorrect definition of a calorie. First, Aubrey says, “In physics, historically, the small calorie is defined as the amount of energy that is needed to increase the temperature of one gram of water by one degree Celsius.” Just after that, she says, “Most of us when we talk about a calorie are talking about a kilocalorie. That's the amount of energy that it takes to raise the temperature of one liter of water by one degree Celsius and that's at sea level.”
Technically, the correct definition of a kilocalorie is the amount of energy needed to raise the temperature of 1 kilogram of water by 1 degree C (at room temperature and sea level, 1 liter of water weighs 1 kilogram). It's interesting that they chose to use liters in the definition here, given that nutrition textbooks and articles all use grams or kilograms. This is functionally unimportant but it does raise questions about their exposure to academic resources around nutrition!
Next, they try to “dig into calories in, calories out.” As noted above, Michael begins by saying, “To me, the phrase, calories in, calories out has always had the same amount of usefulness as saying like, ‘Well, to win a basketball game, you have to score more points.’” This implies that calories impacting mass gain or loss is so self-evident as to be practically useless information. He then says, “whether or not it's true is completely irrelevant,” while proceeding to try to prove that it isn’t true. Indeed, Aubrey later says, “It's incredibly clear in this research that calories in, calories out is not a thing.” This is both not at all true of the research and also a very conflicting message. Which do they believe? Is it a completely obvious law of physics or is it “not a thing”? (Hint: it’s definitely a thing.)
This is followed by a statement that “calories in, calories” out is wrong because “the first law of thermodynamics only applies to closed system.” Later, Michael says, “People who bring up thermodynamics right after calories in, calories out don't know shit about thermodynamics, I guarantee.” To which Aubrey responds, “I'm sure you're right. Because if you do, you know what a closed system is, right? Which is nothing gets in, nothing comes out. Our bodies are not closed systems. You're constantly eating food, breathing air, you're in an environment.”
This is a fundamental misunderstanding of the first law of thermodynamics (thermodynamics absolutely applies to human bodies). Thermodynamics are inescapable, and bioenergetics are governed by these rules. There are numerous scientific articles about this, but here is a helpful guide for non-scientists. I want to stress that there are no serious academics who argue that the first law of thermodynamics does not apply to humans. It is unclear where Aubrey and Michael are getting this information. In fact, one of the sources that they themselves cite for a different reason, The energy balance model of obesity: beyond calories in, calories out, states, “To be clear, all theoretical models of obesity, including the CIM, must satisfy the principle of energy balance to avoid violating the laws of physics.”
Additionally, Aubrey argues that “calories in, calories out” is not applicable to humans because human bodies don’t operate the same way as calorimeters. She says, “Okay. All of this calories in, calories out shit assumes that human bodies operate in the same way as a calorimeter. We don't. Digestion takes time. It's a bunch of chemical reactions are happening in your body. It's real slow and our bodies don't actually extract all of the calories in a given food. You might be eating 200 calories worth of something, but your body might only be able to absorb 100 calories of it.” Unfortunately, this is another example of Aubrey not understanding the science. The “chemical reactions” that Aubrey mentions are the same as what is happening in a calorimeter. Here are some great references that simplify the physiology of human metabolism: From Mass to Energy: The Basic Physiology of Calories and The “Calories In, Calories Out” Confusion: A Comprehensive Guide to Understanding Energy Balance. “Calories in, calories out” is based on the fact that human bodies break down protein, carbohydrate, and fat to produce ATP, that ATP fuels chemical processes in the body, and that we can measure the heat lost in the production and utilization of ATP. This heat can be measured and expressed as a unit of energy, for example a (kilo)calorie, and used as a proxy for mass change. It's entirely true that our bodies extract different amounts of macronutrients from a given food based on factors like degree of refinement (more refined food/less fiber = increased macronutrient absorption), but that is part and parcel of “calories in, calories out.”
Confusingly, Michael also attempts to discredit “calories in, calories” out by providing an example which completely supports the phenomenon. He says, “My understanding of people who have lost weight and kept it off for a long time, because like those people do exist is that basically, it's ongoing calorie restriction and they're also exercising a lot more. Their body never gets to the lower setpoint. The amounts of weight that people are able to keep off over the long term are relatively small. It's like people that have lost 10% to 20% of their body weight. The data on this is really bad because the only source of data on this is this thing called the National Weight Loss Registry, which is self-reported and no one knows how true any of it is.” This is how thermodynamics work: if you chronically take in more energy than you expend, it gets stored as adipose tissue. Maintaining weight loss requires you to not chronically take in more energy than you expend. This is explained very nicely in the Kevin Hall paper that they referenced.
In the past, Michael and Aubrey have spoken about the low success rates of maintaining weight loss long-term. However, in this episode, Michael goes a different direction, saying, “I also have not heard of someone who's just been fat their whole life, taking it off and keeping it off. Although, I'm sure those people exist, because it's a big country and something about it exists.” This would have been an opportunity to dive into the research, but since Michael did not do that, here are several papers about people who have kept weight off long-term. It is pretty well-established that about that 20% of individuals are able to keep significant weight off: “These data, along with findings from the National Weight Control Registry, underscore the fact that it is possible to achieve and maintain significant amounts of weight loss. Findings from the registry suggest six key strategies for long-term success at weight loss: 1) engaging in high levels of physical activity; 2) eating a diet that is low in calories and fat; 3) eating breakfast; 4) self-monitoring weight on a regular basis; 5) maintaining a consistent eating pattern; and 6) catching ‘slips’ before they turn into larger regains. Initiating weight loss after a medical event may also help facilitate long-term weight control.”
This section is wrapped up by Aubrey claiming that “calories in, calories out is not a thing.” And that it is just accepted by researchers uncritically and that it is pervasive because of fat-phobia. As we’ve already discussed, “calories in, calories out” (referred to as energy balance in research) is very much a thing, and it is the thing that governs mass gain or loss. Environmental, genetic, and hormonal factors influence ENERGY (i.e., calories) IN and ENERGY (i.e., calories) OUT, but mass gain necessitates that more energy be taken in than expended, and mass loss necessitates that more energy be expended than taken in. Examples of factors that influence this include:
Physical activity levels influence whether energy (specifically carbohydrate) taken in is converted to fat for storage or used for immediate needs such as replenishing muscle glycogen
Environment influences type and amount of food available
Foods with certain textures and tastes are slower to trigger satiety signals
Protein, fiber, unrefined grains are more satiating
Bottom line, the factors that Aubrey and Michael mention impact how many calories someone eats, and if that amount is more than expenditure the difference is stored as adipose tissue. “Calories in, calories out” has not been debunked. There is no escaping energy balance. This is, once again, very clearly stated in the paper they cite.
Later in the episode, Aubrey and Michael try to suggest that “calories in, calories out” is wrong because “…it doesn't account for the energy that's actually expended in digesting your food. We now think that between 10% and 15% of the calories of given food are actually just used in the digestion of that food.” Strangely, the paper that they cite in support of this does not say anything about that and actually entirely supports “calories in, calories out”. This is also another example of Aubrey not understanding thermodynamics. Digesting food IS part of “calories out.” This would be highly variable depending on the food (i.e., macronutrient profile) and the way it is prepared (i.e., raw or cooked) and what it is eaten with. She is broadly referring to the thermic effect of food (TEF) without using the scientific term, which is something already accounted for in all energy balance equations. Leaving out all nuance, Aubrey takes this 10% at face value and continues, “Take 10% off the top, it also doesn't account for a ton of stuff that we've learned about your endocrine system, and hormones, and how those influence body shape and size. It doesn't account for cortisol, or ghrelin, or insulin. All of those are hormones that are known to impact your digestion, your blood sugar, your hunger and satiety cues, all of that kind of stuff is completely left out of this. It also doesn't distinguish between what the difference is between calories from different sources. It's not distinguishing between calories from fat versus carbs versus protein, sure, but also, I didn't think the jury was still out on calories from alcohol.” So again, as mentioned multiple times so far, all of this is absolutely taken into account with “calories in, calories out”. Discussions about the TEF unequivocally do differentiate between calories from different sources; it's incredibly misinformed to suggest that this isn't already accounted for. We need to underscore: “calories in, calories out”, aka energy balance, is not a diet someone made up. It is a description of how bodies use and store energy.
There are two final things along this line we’d like to comment on. First, Aubrey says, “Right. Totally. That's actually another point that these authors of this paper bring up is they're like, ‘Look, look, look, look, look, even if we came up with the best possible population level modeling of what will generally contribute to weight loss or weight gain at the population level, that's not going to translate into individual behaviors because it can't capture individual biological differences.’ You can restrict calories all day long for someone with lipidemia. They're not going to lose weight in the same way that a person without lipidemia would lose weight and there's just not really a handy-dandy calorie calculator that incorporates all of those things and can just go, ‘All right, your personal calorie level is this.’ No, we don't know how to do that. And even if we did, again, calorie restriction doesn't produce weight loss long term, it slows you way down over time.” All of this is false. Calorie restriction does produce weight loss long-term (how does she think that long-term weight loss happens?). And, again, none of this contradicts “calories in, calories out”. It is a straw man argument to suggest that scientists think that it’s a one-size-fits-all rule. Population-level models NEVER apply to individuals. They are not supposed to apply to individuals. It’s also important to point out that “calorie restriction” is not a monolith, and can encompass anything from a 1% deficit to full starvation. Different points along that spectrum have very different consequences for health, ranging from negligible to extreme.
Finally, Aubrey says, “This straightforward just restrict calories thing, calories in, calories out, just doesn't work. The most recent entry into this set of like, ‘Maybe it's this, maybe it's this, maybe it's actually this,’ about weight loss and calories is a 2022 paper from the American Journal of Clinical Nutrition that actually argued that the brain is the primary organ that governs weight loss. Not consciously, but nearly all subconsciously. We're trying to consciously act our way out of a thing that is happening in our bodies without our awareness. We're trying to be like, ‘No, you just need to have enough willpower.’ Well, a lot of the research shows that willpower around food is just how much ghrelin is in your system. In that same article, they say, ‘BMI is highly heritable and genetic differences explain approximately 75% of BMI variability among individuals.’” At the risk of repeating myself, no scientists are saying that this is straightforward nor saying it doesn’t work. In fact, the opposite is true, even in the articles that they cite for this episode. And BMI being heritable does not mean that the first law of thermodynamics does not apply. It’s also important to point out that restricting calories is not the same as “calories in, calories out”. It is only one half of the equation (calories in).
2) 3,500 calories =/= 1lb of body weight
We’ll take this section point-by-point, because there is a lot of misinformation. The TLDR is that the 3,500 calories = 1lb of body weight estimation is outdated and we know now that it isn’t true. That does NOT call into question whether “calories in, calories out” is valid. It’s an entirely normal phenomenon in science for us to be improving our knowledge as our technology and analytic techniques advance. It’s great to spread the knowledge that 3,500 calories =/= 1lb, but to dunk on it as if scientists don’t already know this is naive. Ok, on to the episode content:
There is this paper that gets published in this Nutrition Journal, by an MD named Max Wishnofsky. "Calories in, calories out is sometimes referred to as Wishnofsky's rule." He laid out an analysis of existing literature on weight loss, and calories, and food, and all that kind of stuff. And concluded that each pound of fat lost or gained, each pound of fat tissue contained 3,500 calories.
This is a common distortion of Wishnofsky’s paper. He actually wrote: “In clinical studies by Strang et al. on weight reduction on obese individuals who were on a low-calorie diet a value of 3,500 cal was obtained for each pound of body weight lost. The conclusion can be drawn that 3,500 is the caloric value of one pound of body weight lost.” (Emphasis ours) While it is commonly stated that 3,500 is specific to a pound of fat, that’s actually not what he stated at all. It’s a pound of body weight (note that this has been shown to be incorrect, but it’s important to correct for the record).
He determines that each pound of human fat tissue, human adipose tissue has the what he calls the caloric equivalent of 3,500 calories. From there, he concludes that cutting 3,500 calories from your diet would lead to the loss of one pound of fat tissue. Years later, there's this very influential medical textbook. It's called Modern Nutrition in Health and Disease. It takes up this Wishnofsky's rule and writes that "Losing one pound would require an energy deficit of 3,500 calories."
This is not what the book says. It says, "an energy deficit of approximately 3500 kcal is needed to lose 1 lb of body weight". Somewhat irrelevant, given that we now know that his calculations were flawed. But body weight and body fat are not synonymous: “weight” includes water, lean mass, and body fat.
A bunch of the assumptions that Max Wishnofsky made in developing this calories in, calories out approach have since been disproven.
Again, “calories in, calories out” is simply a law of energy balance. It has not been disproven. It is fundamentally true that in order to lose weight, energy in < energy out. That’s not controversial. Max Wishnofsky also did not develop “calories in, calories out” and he didn’t make any assumptions. He calculated the calories in one pound of bodyweight based on clinical data.
If you eat 3,500 calories, fewer, you don't just keep losing a pound a week until nothingness, until like the singularity. Your body eventually is going to adjust and you're going to plateau.
This is another example of a straw man fallacy. No one is suggesting that you would disappear if you had enough of a calorie deficit. Everyone knows that there are bones and tissue and other things in your body that take up space. But has Michael ever seen someone with extreme anorexia or wasting disease? People do become dangerously thin because of lack of calories. If “calories in, calories out” was not true, no one would waste away from anorexia or any other disease that limits appropriate caloric intake.
Totally, totally. And even highly active people, if you apply this kind of formula of calories in, calories out to Michael Phelps, who eats 7,000 calories a day, you'd be like, "That guy is getting fat," even with the levels of activity that he has. But he's not. There are people that we all know who eat very small amounts and are fat people or eat very large amounts and are thin people. He assumes that weight loss is a totally linear process and it's almost like a ledger. Like you make a deposit or you make a withdrawal and that's it.
This mostly underscores Aubrey’s misunderstanding of physiology. Who is she talking to that says Michael Phelps would get fat eating that much? Most people realize he is an incredibly muscular, super active human who needs more fuel than the average human. It’s also well understood at this point, thanks partly to Kevin Hall, that short term fluctuations are largely irrelevant but long-term energy intake and expenditure patterns determine mass gain or loss.
But he's using a bomb calorimeter to determine all of this and human beings are not containers of pure oxygen suspended in water. When you take in less energy, your body also expends less energy. Over time, it does get harder and harder to lose weight. You lose less and less weight over time if you're restricting calories. And not only that, but when you lose weight, you're losing fat. Yes, but you're also losing muscle mass.
Wishnofsky did not use a bomb calorimeter for this. He looked at actual weight loss in highly controlled clinical trials. The fundamental law of energy balance does not suggest any linear relationship. It does not get “harder and harder to lose weight”, but the energy deficit required to lose weight may be unsustainable or unhealthy at a certain point.
Earlier you mentioned your body does downshift. It gets harder to lose weight as time goes on. In 2011, this researcher named Kevin Hall does some research to directly challenge Wishnofsky's rule. What he found was that if you only factor in that metabolic downshift and burning fewer calories, Kevin Hall found that Wishnofsky's rule overpredicted weight loss by 100%.
Here is the paper that they are referring to: What is the Required Energy Deficit per unit Weight Loss? - PMC (nih.gov). While the article that they linked to quotes Hall saying that the Wishnofsky rule predicted double the weight loss over a year, his paper concludes, “the rule of thumb approximately matches the predicted energy density of lost weight in obese subjects with an initial body fat above 30kg.” This is entirely understandable given that the rule of thumb was derived using clinical data from only obese individuals (problematic for developing a rule supposed to apply to everyone!).
He said that, "Calories in, calories out would say you would lose twice as much weight as you actually would, given the way that your metabolism downshifts."
Kevin Hall never said this. If you Google this quote, the MP transcript is the only hit.
I'll also say there is some research, most famously with the Biggest Loser study that finds that calorie restriction in the long-term actually damages your metabolism and that downshift is permanent. In 2015, just four years later, there's a paper that is released in the Journal of the Academy of Nutrition and Dietetics and they tried to do this omnibus like, "Here's everything that's wrong with calories in, calories out." It's authors essentially concluded that the rule is easy to use, Wishnofsky's rule and calories in, calories out is easy to use, but "lacks a contemporary scientific foundation and leads to a large error in weight loss prediction even over the short term."
I think Aubrey and Michael would agree that The Biggest Loser is a VERY extreme and unhealthy degree of caloric restriction and is not applicable to all people, so it is unclear why they would use this as an example (except that it fits their narrative). It is problematic (and incorrect) to say that caloric restriction “damages” your metabolism. It is well-established that metabolic rate decreases with weight loss. That is not “damage” - it is a characteristic of human bodies: less fat mass requires less energy. Anyway, Aubrey is referring to this study which, contrary to her statement, could not have found that the downshift was “permanent,” as the study was only over the 6-week period of the show. Interestingly, at 6 years post-show, the participants who were most successful at keeping off the weight were the ones with the largest metabolic adaptation (see follow-up study). This could be because the RMR increases as people regain the weight back (i.e., reverse-causation) but it still suggests that metabolic adaptation is not the reason why people can’t maintain weight loss. But again, THIS IS A SUPER UNHEALTHY TV SHOW PREMISE. Not how anyone in real life should lose weight.
The paper that Aubrey is referring to in the Journal of the Academy of Nutrition and Dietetics is from 2014. The article has nothing to do with “calories in, calories out”. What it does do, is tackle the issues with 3,500 calories = 1lb of weight loss as a predictor of future weight loss. This is about predictive models of weight loss based on reduced calorie intake. All of the models in this paper show a reduction in body weight with reduced calorie intake (i.e., calories in, calories out!), just at differing rates. Again, science is iterative - the fact that we are developing better models does not in any way negate that energy balance underlies weight gain/loss. It is worth highlighting the last paragraph of the paper:
“Rather than promoting these newer dynamic weight loss prediction models as definitive, we have only started the complex construction and validation process. The thermodynamically based models rely on energy and metabolism data which contain measurement error and this error propagates into model terms. Moreover, there is always a degree of individual biological variation which cannot be captured by a model constructed in part from population averages. Far more research is needed on improving model terms, supplying more accurate empirically derived coefficients, including the dose-dependent influence of exercise or the impact of weight changes in the presence of disease, and effective delivery through software designed for clinical applications. Moving this approach forward will strengthen the links between modern dietetics and basic nutritional and physical sciences.”
This is how science is portraying our knowledge of calories and weight gain/loss. Not the way that Michael and Aubrey are portraying it.
Aubrey: We talked earlier about calorimeters and bomb calorimeters in particular. He's measuring the calories in a given food and then what he wants to find out is, what's the caloric availability of that food? Of those calories, how many can your body use? The way that he does that is he calculates the caloric value of a food and then he feeds that same food to a bunch of different humans… He collects their poop after they eat that food, and then he burns the poop in the bomb calorimeter... Caloric value of the food minus caloric value of the poop equal calories you absorbed and used.
Okay. It says, "Well Atwater took into account the fiber in food, which we can't digest." Hello, sweetcorn. "As well as the nitrogen extracted from protein and excreted as urea in our urine, he didn't take into account the heat given off during metabolism. This is known as diet-induced thermogenesis and is the significant energy cost of converting protein, fat, and carbs into the amino acids, fatty acids, and glucose that our body needs." Okay, so, the food to poop pipeline is leaving out a bunch of extra stuff that would have affected the calorie counts.
You can see this is not true if you read Atwater’s actual report: Experiments on the metabolism of matter and energy in the human body : Atwater, W. O. (Wilbur Olin), 1844-1907 : Free Download, Borrow, and Streaming : Internet Archive. This was an incredibly complex study which captured energy released by respiration, urine, and heat released by the body, as well. This simplification is convenient for Aubrey’s case, but it isn’t scientifically accurate and it undermines her argument that the first law of thermodynamics does not apply here. It seems like Aubrey and Michael got their information about this study from the NewScientist article, instead of reading the primary sources. If you read the report linked above, you will see that Atwater did, in fact, capture thermogenesis. There were definitely a LOT of issues with Atwater’s experiment (again, not surprising given how long ago this was), but this was not the issue. There is a great article breaking down Atwater’s experimental methods and the things he got right and wrong. It is notable that he said of his own study, “We do not assume that the coefficients represent the actual availability of the nutrients of the different kinds of food materials under all circumstances or in all of the food materials of any given class.”
3) FDA Nutrition Labels
This is another wild section, because it begins with Aubrey saying, “I think most of us presume that 2,000 calories per day is the correct amount of calories to eat if you want to maintain the same weight.” This is a bizarre assumption to make, and not supported by any research that we’ve seen. Most of this section is based on an article in the Atlantic, instead of primary sources. We haven’t been able to verify the data from the Atlantic article. Also, Aubrey explicitly acknowledges that 2,000 calories was never meant to be a guideline. She says, “The FDA says that they didn't actually intend this 2,000 calories per day to be a nutritional guideline.” And then for the rest of the podcast, she rips into this as if it is a guideline, saying that the 2,000 calories number was chosen to make people eat less and because it was supposed to curb obesity. Very unclear how she got from point A to point B. Here is some fact-checking:
That means that it was designed to be easy for consumers to understand what was in foods, but not necessarily meant to be like here's the hard and fast information/not be a recommendation for every individual that you need to eat 2,000 calories a day. They're like, "No, no, no, we pick 2,000." In part, because it was a round number that people's brains could hook on to more easily, essentially, they wanted consumers to be able to compare the nutritional value of different foods to one another, and compare apples to apples a little bit. But in order to do that, they had to standardize serving sizes, they had to standardize calorie counts, they had to come up with a standardized system, so that everybody was getting the same information.
The 2,000 calories per day piece has nothing to do with how many calories are in a food product. The “calorie counts” are not standardized. If Aubrey is referring to the % RDA, that’s different than “calorie counts” and is done in the rest of the world, as well (as she mentions later). Food labels in other countries give nutrition information per 100g. It’s not unreasonable to set a reference for people to be able to understand the nutritional content of the food they are going to consume.
2,000 calories a day was not based on nutritional or medical best practices. It was not based on recommendations from scientists, it was not based on research into any optimal diet, or weight management, or any of that stuff. It was based on Americans self-reported calorie intakes through USDA surveys.
Again, Aubrey has already stated that this wasn’t supposed to be a guideline. So why would it be based on any science? It was just a reference number. Anyway, here is the actual history here: the 1990 Nutritional Label and Education Act of 1990 required that serving sizes be based on amounts that people actually consume, rather than recommended portion sizes or 100g as in some other countries. This was something that was discussed - it was not just a rash, offhand decision. They call this the RACC - Reference Amounts Customarily Consumed. I’m not sure why this is problematic to Aubrey. That the FDA would attempt to capture % RDA based on what people report consuming makes sense…? As Aubrey noted, these RACCs were updated in 2016, which is why nutritional labels changed in 2020. They are reflecting what people actually consume. Additionally, this was not based on self-reported calorie intake. It was based on food frequency questionnaires - people were asked what they eat and the calories were calculated after that.
Anytime you issue rules, which are like the things that a state agency can just decide for themselves, they don't have to wait on Congress, or the President, or the state legislature, or anything else. You have to have what's called a public comment period. So, I am going to send you-- This is a little bit of a long quote. this is from the Marion Nestle piece about how did we get from 2,350 calories per day as generally the middle of that range that they were provided to 2,000 calories a day.
It’s unclear where Marion Nestle pulled this 2,350 number from, as the USDA reports from this survey are not consistent with that. In the 1987-1988 survey, it was 1,785 (2,154 for adult males and 1,497 for adult females, see page 46). In the 1989-1991 survey, the mean calorie intake across ALL individuals was 1,839 (2,213 for adult males and 1,556 for adult females, see page 118). And in the 1994-1996 survey, it was 2,002 (2,455 for adult males and 1,646 for adult females, see page 4). The issue isn’t whether or not these numbers are appropriate, but whether or not they are true to the data. And they are.
It says, "Despite the observable fact that 2,350 calories per day is below the average requirements for either men or women obtained from doubly labeled water experiments, most of the people who responded to the comments judged the proposed benchmark too high. Nutrition educators worried that it would encourage overconsumption be irrelevant to women who consume fewer calories and permit overstatement of acceptable levels of eat less nutrients such as saturated fats and sodium. Instead, they propose 2,000 calories as consistent with widely used food plans close to the calorie requirements for postmenopausal women, the population group most prone to weight gain a reasonably rounded down value from 2,350 calories easier to use and 2,350 calories and therefore a better tool for nutrition education. Whether a rounding down of nearly 20% is unreasonable or not, the FDA ultimately viewed these arguments as persuasive." Wow.
See above. Marion Nestle is an expert in her field, but we don’t know where she’s getting these numbers from. The only place we see 2,350 is from her. It’s also worth noticing that directly after that, Marion says, “As to how many calories you personally need, I think they are too difficult for most people to count accurately to bother. The bottom line: If you are eating too many, you will be gaining weight.” In other words, “calories in, calories out”.
It appears from this account that the primary reasons were, this is going to seem irrelevant to women who are already restricting calories. They just won't pay attention at all. If we tell them 2,350, then they're going to eat more than that. We have to tell them less. It also accounted for people eating more than 2,000 calories. They thought that they would say 2,000 and people would eat more than that. It is introduced this what is in retrospect and entirely arbitrary number. It started out with bad data and they were like, "Here's the middle of that bad data" and then they were like, "No, that's too high." …And then walked it back to 2,000 calories. It just seems this very clear example of the ways that our public policy around food and the information we have access to is just always shaped by our social fears and anxieties around fatness and fat people and our disgust or rejection around fatness and fat people, right?
Again, as Aubrey said, this was not a guideline. We are not sure how Aubrey got from acknowledging that this was not a guideline to attributing this to the FDA trying to make people eat less. This has nothing to do with fat-phobia or anxieties around fatness.
It is this very familiar two step, where whenever you criticize these things as the 2,000-calorie thing seems fake and arbitrary, you then get the response that's like, "No, no, it's science." And then you're like, "Okay, let's talk about the science." And then the science is fucking trash.
Again, no one is saying this is science. Aubrey already flat out acknowledged this is not a guideline. The science is not “fucking trash,” but this podcast did not cover any of the science.
It's also weird how, if the first step can just be admitting like, "Okay, we chose this number, because we wanted to raise awareness of the dangers of obesity. That's why we did it."
This is a very bizarre conclusion to come to after flat out acknowledging it’s not a guideline. This has nothing to do with obesity.
And we should be clear with people that we designed this as a communications tool, not as dietary guidance.
This is literally exactly what the FDA is doing. And Aubrey already acknowledged that. This is very confusing.
Well, and when we get into how calorie restriction messes with your metabolism and changes how your body functions, it's not just like, "Oh, we got this wrong." There are repercussions. And this feels the most benign information just like, how many calories are in a food? It's just a fact. Here you go.
Yes, crash dieting and severe restriction has negative physical and psychological impacts. No, that is not the only or recommended option for people who do choose to pursue fat loss. Furthermore, there are also repercussions to misrepresenting how physiology works: making informed choices requires a person to first be informed.
I'm always really struck at how consistent it is that scientific institutions are like, "We have to twist the science to get this outcome that we want and the outcome is always like well, everybody needs to be thinner." I don't think anyone seems to have contemplated or asked really basic questions of like, "Is this a goal that we want or is this going to have really predictable, unintended consequences?" I really think the variable is like bias. I think being biased against a group just makes you roll your eyes at their concerns.
This is such a dangerously bad take. The scientists are not twisting anything. This wasn’t even based on science. The choice of 2,000 came from data from surveys. This was already acknowledged. This literally has nothing to do with obesity.
Closing thoughts:
Imagine that you went to a financial advisor and said you wanted to get out of debt. They would tell you, “You need to earn more than you spend.” Now imagine your income and expenses are both variable and not easy to predict in advance. And your income has all of these taxes taken out, so your net income isn’t actually what you think it is… None of these things mean that it isn’t true that you need to earn more than you spend in order to gain money. Aubrey and Michael’s claim that “calories in, calories out” isn’t true (although they also say it is true??) is similar to this. The fact that the process is complicated doesn’t negate the truth of the law of thermodynamics.
TLDR:
Having uncertainty in the measures does not negate the underlying truth that energy imbalance is the mechanism here.
Crash diets/severe restriction are not recommended and are not the only option for creating a deficit.
People who keep weight off long term do so because they develop and maintain new habits.
Metabolism is complex but also well understood.
Calories measure heat that is the result of internal chemical reactions, which serves as a proxy to estimate energy expenditure.
Suggested readings:
Seems arbitrary to correct the 1 liter vs 1 kilogram when the density of water means they’re the same thing?
I really appreciate this, because as somebody who had Anorexia as a teenager and became very underweight, I know that you can indeed continue to lose weight if you restrict your calories, and I had the same thought when I listened to this episode. I get what they were trying to do with this episode. I felt like they were trying to explain why people who say to fat people "calories in and calories out!" are incredibly unhelpful (which they are, it's factually correct, but actually counting calories and working out how many you need for a deficit is somewhat complex), but their logic seemed confused. They're right that people oversimplify the factors which affect the calories you consume and expend. Some people don't seem to know about RMR / BMR at all, and think you have to actually burn off every calorie you consume through activity. There's a lot of misconception. But I don't think this episode helped with that, because as you point out, it's not the science that's wrong here, it's the interpretation that ordinary people make.