The high fat VS high carb diet is arguably one of the most heated debates in nutrition and fitness and our society at large. What drives the debate’s fervor is our desire to understand the underlying driver of one of the direst problems our world is facing, the obesity epidemic (perhaps only second to climate change).
The Rise of Empiricism in Weight Loss
Ignorance leads to conjecture, and conjecture leads to empiricism. This is a typical evolution found in the collective intelligence of humans and has been ever present since the dawn of history. In simple words, if I can’t understand something (Ignorance), I will try to make sense of it by establishing correlations based on the available information (conjecture). If my correlations can somehow explain the result, then I proceed to establish them as a form of an axiom, which I then try to preach to others (empiricism).
This is what happens with weight loss. Uncounted millions failed to lose weight despite continuously cutting calories and restricting their eating leading many to seek refuge in nutrition programs of any possible combination and experiment with excluding specific food sources or choosing to overeat others. In several cases, the motivation behind some of these attempts was also founded on falsely understood concepts of human physiology. For example, the choice to exclude fat is based on the premise that fat makes you fat and the misconception that since fat is what we are trying to lose, it’s probably better not to eat it in the first place. Conversely, others used the association of diabetes with blood glucose to demonize carbs, arguing that excessive consumption gives rise to the disease and should thus be mitigated as much as possible. Some decided to avoid using even falsely understood concepts of human biology and resorted to history, arguing that because ancient humans were supposedly healthier, mimicking their eating habits would lead to weight loss (see Paleo diet).
Irrespectively, however, of the justification used, many proponents of these nutrition concepts lost weight! This inevitably led those who conceived them to try and propagate them out of an intention to profit or, in several cases, out of genuine altruism. In this process, the obvious first step was establishing their initial idea (e.g., exclusion of carbs) as a recipe for success. Once a nutrition concept gathered enough steam and popularity, it became a movement. The most popular are the Keto, Atkins, Paleo, Carnivor, and Low-Fat diets.
Conflating Correlation with Causation
Yes, followers from all popular movements lost weight, many of them for good. However, without an accurate understanding of the laws of physics governing human biology, which are no different than those governing the universe we live in, they were all doomed to deem their choice as the mechanism that explained success. The fixation on their preference and ignorance of how human biology works led them to disregard the myriad other factors that could have also played a role and perhaps be the deciding factors in explaining weight loss. In short, people’s desire to explain a phenomenon urged them to think that their choice, for example, to eliminate carbs, wasn’t just correlated with weight loss but causally related or that the elimination of carbohydrates was a defining factor in one’s successful weight loss process.
Many studies and longitudinal data regarding changes in dietary habits over time have shown that the macronutrient breakdown in a nutrition program is not the defining factor in weight loss. Some of the most astounding studies and facts are:
- One of the most recent landmark studies conducted at Stanford University that examined a cohort of 609 individuals equally distributed between low carb and a low-fat diet showed no significant differences in weight loss between the two groups.
- It’s not uncommon to run into low-carb or low-fat followers who look to blame the obesity epidemic on the respective macronutrient they have demonized (carbs for low-carb supporters and fat for low-fat supporters). Low-fat supporters portend that Americans became progressively overweight because they indulged in excessive fat eating over the past decades, whereas Low-carb supporters argue the same for carbs. The reality is that Americans have increased their carbohydrate and fat intake by approximately the same amount between 1970 and 2010, as shown by a recent study published by Pew Research comparing the dietary habits of Americans.
- A similar argument structured on the supposed preference towards fats or carbs in previous centuries and prehistoric times is also common. Some argue that older generations relied mainly on animal protein, others ate carbohydrates predominantly, while others that prehistoric people consumed uncooked food. Whether one wants to use history to support the vegan, vegetarian, or carnivore diet, there is enough historical evidence to support all claims simply because our ancestors weren’t all the same. Some were forced by nature to rely more on animal protein, while others relied more on a plant-based diet due to population growth and the evolution of irrigation. One thing, however, is undeniably true: Although societies over millennia across all corners of the earth were exposed to countless different diets, no one ever encountered the diabetes and obesity pandemic until the middle of the 20th century.
So what changed after the 1940s? Although there seems to be no solid evidence that one diet is better than the other, there is now absolute convergence over the root cause of obesity: Since the 1940s, people have been eating more and burning fewer calories. As a result, people created a calorie surplus which, according to the 2nd law of thermodynamics, has to be converted into body mass, in other words, excess body weight. Decades of constantly eating more and moving less have now kept billions of people in a perpetual state of calorie surplus, which equates to a constant increase in body weight. Reversing this can only be attained through a calorie deficit, the state of eating fewer calories than you consume.
Simply counting calories isn’t enough, however. Indeed, from a physics perspective, the sole determinant of weight loss is the attainment of a caloric deficit, in simple words, ensuring that the calories you eat are less than the calories you burn. Several studies, however, have shown that people’s failure to lose weight despite restricting their diets is due to the notorious “metabolic” slow down, a phenomenon that reduces the calories a person’s body burns. This closes the gap between calories eaten and burned, thus eliminating calorie deficit, the prerequisite for weight loss.
For example, if a person was initially burning 2000 kcal per day and eating 1500 kcal per day, the calorie deficit would be 500 kcal per day. If the person’s metabolism slows down to 1600 kcal per day, the deficit is almost completely gone, and thus by continuing to eat 1500 kcal per day, the person will experience little to no progress.
This problem, however, can become much more severe. Abandoning the diet and returning to regular eating habits will not re-ignite one’s metabolism. Several studies, including the one conducted on the participants of “The Biggest Loser,”has shown that going on a diet that reduces your metabolism will cause a long-lasting reduction in your metabolic activity that can not be undone by simply getting off the diet.
All the above culminate in the conclusion: “The only way to lose weight sustainably is to achieve a calorie deficit that is sustainable for your lifestyle AND your metabolism.” This means that although you may have found a way to cut calories by counting them, going keto or vegan (i.e., creating a sustainable deficit for your lifestyle), neglecting your food choices’ impact on your metabolism can be detrimental. Therefore, dieters’ number one concern should be preventing their metabolism from slowing down. This can only be attained through a holistic program with the proper training, nutrition, and recovery regimens. For a detailed overview of what such a program should include, read our blog post, “Weight Loss is about Physiology, not Psychology.”
The Problem of conflating Correlation with Causation
Many who follow popular diets dismiss the notion of having to care about more than just a specific dietary element (e.g., carbs) to lose weight sustainably. Those who do so typically abide by the rationale: “Why do I care about all this, since what I am doing is working for me.” Well, there are several reasons one should care to understand the actual mechanism. Here are the most important ones.
- Success may be temporary. It is common for individuals who approach weight loss from a diet-only perspective to experience a constant cycle of weight loss and re-gains. What’s typically the case is that dieters are hyper-focused on achieving the one thing their diet dictates, in the case of a keto diet, for example, the almost complete elimination of carbs. High fat intake will usually suppress hunger, lead the individual to reduce calories, and thus enable him to lose weight. However, the lack of adequate and appropriate exercise will almost certainly decimate the individual’s metabolism. As a result, based on the process described above, the individual is doomed to regain weight once regular eating habits return.
- Development of unhealthy habits. Diets such as Keto and Atkins that lead people to a drastic reduction in food intake from vegetables and fruits will inevitably deprive one of the valuable nutrients required for overall health and mental performance. Moreover, since the usual “selling point” of these diets is that one can eat as much animal fat as possible, dieters will often indulge in excessive consumption of unhealthy items (butter, fatty meats, etc.) that can cause cardiovascular and other conditions.
- Never reach a 360º healthy lifestyle. As explained earlier, cutting calories by simply counting them or suppressing hunger by overconsuming a specific macronutrient (i.e., protein or fat) are fundamentally the same. They will yield short-term weight loss results but will almost always impact a person’s metabolism. A low metabolism will lead to recurring weight re-gains or a lifelong sentence of restricted eating to maintain weight. A sustainable eating schedule is impossible without proper training and a recovery regimen. As a result, one’s over-fixation of following a specific macronutrient and turning a blind eye to all the other longevity requirements is certainly not the right path to better health.
Ultimately most dieters diet because they want to live longer and better. However, long-term health is not only about maintaining a healthy BMI. For better or worse, the human body is a complex system that requires attention on multiple dimensions. Some of the key ones are:
- Providing the proper nutrients to your body
- Maintaining strong bones that will prevent suffering from myoskeletal problems is the most likely factor to diminish your quality of life when you grow old.
- Maintaining a high cardiovascular and pulmonary fitness, a prerequisite for preventing heart and lung disease, is the 2nd and 1st most common cause of death.
- Maintaining the right hormonal balance that’s vital for mental performance, high energy levels, and mood.
- Maintaining a healthy gut microbiome which is a critical regulator of energy levels and mental health.
To achieve long-term health and longevity, one must follow a lifestyle that includes a well-rounded exercise program, the proper nutrients, and adequate recovery. Undeniably, the most significant peril of being overly fixated on a single element, whether that is counting calories, eliminating carbs, eating as much red meat as possible, or consuming exclusively uncooked food, is turning a blind eye to all the other things that genuinely matter and gift one long and good years of life.