When I was young and running 90-100 miles a week, I could eat all the things without gaining weight. Time is doubly cruel in that it slowed my metabolism and reduced my ability to endure high mileage. Inundated with the usual abundance of high calorie foods, I found I was building an unsightly pudge band around my middle. My first reaction was to try to get back to my old mileage, but I found that I now top out at 70 miles a week and anything more starts breaking me down. Since I could not exercise more, I was faced with the terrible option of eating less. Being something of an expert on critical thinking, I dismissed all the fad diets and turned to science to glean the best way to beat the bulge. Being a philosopher, I naturally misapplied the philosophy of science to this problem with some interesting results.
Before getting into the discussion, I am morally obligated to point out that I am not a medical professional. As such, what follows should be regarded with due criticism and you should consult a properly credentialed expert before embarking on changes to your exercise or nutrition practices. Or you might die. Probably not; but maybe.
As any philosopher will tell you, while the math used in science is deductive (the premises are supposed to guarantee the conclusion with certainty) scientific reasoning is inductive (the premises provide some degree of support for the conclusion that is less than complete). Because of this, science suffers from the problem of induction. In practical terms, this means that no matter how carefully the reasoning is conducted and no matter how good the evidence is, the conclusion drawn from the evidence can still be false. The basis for this problem is the fact that inductive reasoning involves a “leap” from the evidence/premises (what has been observed) to the conclusion (what has not been observed). Put bluntly, inductive reasoning can always lead to a false conclusion.
Scientists and philosophers have long endeavored to make science a deductive matter. For example, Descartes believed that he could find truths that he could know with certainty and then use valid deductive reasoning to generate a true conclusion with absolute certainty. Unfortunately, this science of certainty is the science of the future and always will be. So, we are stuck with induction.
The problem of induction obviously applies to the sciences that study nutrition, exercise and weight loss and, as such, the conclusions made in these sciences can always be wrong. This helps explain why the recommendations about these matters change relentlessly.
While there are philosophers of science who would disagree, science is mostly a matter of trying to figure things out by doing the best that can be done at the time. This is limited by the resources (such as technology) available at the time and by human epistemic capabilities. As such, whatever science is presenting at the moment is almost certainly at least partially wrong; but the wrongs get reduced over time. Or increase sometimes. This is true of all the sciences—consider, for example, the changes in physics since Thales began it. This also helps explain why the recommendations about diet and exercise change constantly.
While science is sometimes presented as a field of pure reason outside of social influences, science is obviously a social activity conducted by humans. Because of this, science is influence by the usual social factors and human flaws. For example, scientists need money to fund their research and can thus be vulnerable to corporations looking to “prove” various claims that are in their interest. As another example, scientific matters can become issues of political controversy, such as evolution and climate change. This politicization tends to derange science. As a final example, scientists can be motivated by pride and ambition to fudge or fake results. Because of these factors, the sciences dealing with nutrition and exercise are significantly corrupted and this makes it difficult to make a rational judgment about which claims are true. One excellent example is how the sugar industry paid scientists at Harvard to downplay the health risks presented by sugar and play up those presented by fat. Another illustration is the fact that the food pyramid endorsed by the US government has been shaped by the food industries rather than being based entirely on good science.
Given these problems it might be tempting to abandon mainstream science and go with whatever fad or food ideology one finds appealing. That would be a bad idea. While science suffers from these problems, mainstream science is vastly better than the nonscientific alternatives—they tend to have all of the problems of science without having its strengths. So, what should one do? The rational approach is to accept the majority opinion of the qualified and credible experts. One should also keep in mind the above problems and approach the science with due skepticism.
So, what are some of the things the best science of today say about weight loss? First, humans evolved as hunter-gatherers and getting enough calories was a challenge. As such, humans tend to be very good at storing energy in the form of fat which is one reason the calorie rich environment of modern society contributes to obesity. Crudely put, it is in our nature to overeat—because that once meant the difference between life and death.
Second, while exercise does burn calories, it burns far less than many imagine. For most people, the majority of calorie burning is a result of the body staying alive. As an example, I burn about 4,000 calories on my major workout days (estimated based on my Fitbit and activity calculations). But, about 2,500 of those calories are burned just staying alive. On those days I work out about four hours and I am fairly active the rest of the day. As such, while exercising more will help a person lose weight, the calorie impact of exercise is surprisingly low—unless you are willing to commit considerable time to exercise. That said, you should exercise—in addition to burning calories it has a wide range of health benefits.
Third, hunger is a function of the brain and the brain responds differently to different foods. Foods high in protein and fiber create a feeling of fullness that tends to turn off the hunger signal. Foods with a high glycemic index (like cake) tend to stimulate the brain to cause people to consume more calories. As such, manipulating your brain is an effective way to increase the chance of losing weight. Interestingly, as Aristotle argued, habituation to foods can train the brain to prefer foods that are healthier—that is, you can train yourself to prefer things like nuts, broccoli and oatmeal over cookies, cake, and soda. This takes time and effort, but can obviously be done.
Fourth, weight loss has diminishing returns: as one loses weight, one’s metabolism slows and less energy is needed. As such, losing weight makes it harder to lose weight, which is something to keep in mind. Naturally, all of these claims could be disproven in the next round of scientific investigation—but they seem quite reasonable now.
KimBoo York says
It’s nice to see someone trying to approach this objectively and not just accepting platitudes because “everyone knows it’s true.”
I’m sure you know this is a huge issue for me — resulting in disordered eating behaviors, yo-yo dieting since I was 12, and obesity. I’m convinced that if I had never gone on a low-calorie diet in my life, I would never have become significantly overweight. The “cure” has contributed mightily to the “disease.”
But that, I think, brings up the issue of complexity. Research into how the gut biome of bacteria affects not only digestion but hunger itself (that is, the brain) is in its infancy. The reasons people gain weight are not simply overeating but due to a wide variety of issues that may or may not be directly related to intake (mental illness is a huge one, as is childhood trauma, and of course prescription drugs and illnesses, etc.). Someone who has lived an athletic and fairly healthy life, like you, is going to need different approaches than someone like me who comes from a lifetime of being mostly sedentary and yo-yo dieting.
I tend to keep a weather eye on research; I grew up during the heady days of “low fat, high carb!!!!” craziness when the nutritional textbooks mother brought home for “light reading” claimed both that a low-calorie starvation diet was devastating to the human brain (in the chapter about starvation and malnutrition) and that a low-calorie starvation diet was essential for healthy fat loss (in the chapter about obesity). I feel a bit paranoid coming from the “TRUST NO ONE!” mindset but given how the sugar industry has really screwed up research efforts for the last, oh, 70 years, it’s hard to take anyone’s claim as anything more than “preliminary”.
Which is a lot of words to say a lot of nothing, I suppose. I certainly have no advice! I loathe being overweight with a righteous, frightening fury and hate my body unconditionally but I know drastic measures lead to catastrophic results, and at this point, my metabolism has been in survival mode for nearly 40 years and is not going gently into anything that suggests physical stress. :/ That said, I hope you find the right combindation of factors that works for you!
Michael LaBossiere says
Good point about the microbes-there has been some very interesting research about how they impact us.
Social norms play a huge role here as well-people advance a limited concept of what is the right way to be and push it hard. That this is a matter of convention is shown by how it shifts and changes across time and societies.
This is a good starting point.
Good article. Nassim Taleb has ideas concerning these things that work quite well, and not only in regards to foods. If humans haven’t consumed something for at least 100 years, there’s a significant risk involved in consuming these things. Thus, the drinks of choice would be coffee, beer, water, milk, and tea. There can of course be new things that will be fine for humans, but this will not be clear for some time. I will let others be the canary in the coal mine. The same rule can be applied to social phenomena and new technologies. Social media, for instance, may change the way human brains process data and reality. it’s difficult to believe that this new interpretation will be more accurate and refined than interaction with the “real” physical world. As you point out, and as history and sociology show, the default setting for human thinking is “conservative”, when we have skin on the game, as Taleb would call it. Humans default at skepticism over wild and new things when they have something to lose. Thus, eat natural, whole foods.
Magus, tell us what you are up to. Are you back in CONUS?
I can’t speak with any authority about philosophy, but every time I use the word “science” without a qualification, I pinch myself to remind myself that I am making a false statement. Well, OK, I don’t, but I should. We use the word “science” to cover so many areas of study, beliefs, hypotheses, experimental results, papers, textbooks, in so many different fields that have very different standards of evidence and uncertainties and constraints that almost no assertion can be true about all of them.
In areas of study that involve multiple independent feedbacks, and that cannot sustain repeated experiments under controlled conditions, science is reduced to an iterated series of post hoc ergo propter hoc observations. Thus, any fields which involve multiple systems interacting with many independent feedbacks such as studies of ecology, turbulence in an open system, and biology at the level of complex organisms in the wild, our understanding converges very slowly. When we add human behaviour as a feedback, it becomes slower still. Experiments show the chemical structure of foods, their breakdown and absorption, and while these are important pieces of understanding diet for weight loss, they do not lead us to a complete understanding, prediction, or prescription.
Which is just a fancy way of saying that while we know that eating less calories will produce weight loss, our best scientific guess about what advice will actually work for a given individual is barely above the level of superstition and historic common belief. I didn’t know that Aristotle argued that habituation to foods can train the brain to prefer foods that are healthier, but it seems to me we haven’t made much progress in the way of practical advice since then.
I know from experience that I can achieve a gradual and undramatic weight loss by the simple step of keeping a food log, noting everything I eat, with its calorie count and food group(s), and make a summary every day. I do not need to set targets or restrict myself in specific ways. The knowledge that I will have to write up my actions is, for me, enough of a control that I will inevitably restrict my calorie intake, and change my ratio of foods eaten. I also know that deciding never to bring breads into the house is an effective measure. I know these things are true for me. I am sure they would be unacceptable or ineffective for others. That human behaviour feedback is just too strong to make generalisations.
I wish you the best of luck with your experiments into what works for you!