In "Why We Get Fat," Gary Taubes challenges the conventional wisdom about obesity and weight gain. He argues that the widely accepted idea of "calories in, calories out" is fundamentally flawed and that our understanding of why people become overweight needs a complete overhaul. Taubes presents a compelling case that it's not how much we eat, but what we eat that truly matters when it comes to weight gain and obesity.
The book takes readers on a journey through the history of nutrition science, debunking myths and presenting alternative explanations for why we get fat. Taubes argues that the real culprit behind the obesity epidemic is not fat or lack of exercise, but rather the overconsumption of carbohydrates, particularly refined sugars and starches.
The Flawed Logic of Conventional Wisdom
The Calorie Myth
One of the central themes of "Why We Get Fat" is the dismantling of the widely held belief that weight gain is simply a matter of consuming more calories than we burn. Taubes argues that this oversimplification fails to account for the complex processes occurring within the human body.
The conventional wisdom suggests that our bodies are like balloons – they expand when we put energy in and shrink when we take energy out. This simplistic view has led to the widespread belief that fat people are simply lazy and gluttonous. However, Taubes points out that this explanation doesn't address why some people consume more calories than they need in the first place.
Moreover, the author presents historical evidence that contradicts this simplistic view. For example, he cites cases from the early 20th century where impoverished and underfed populations still had high rates of obesity, particularly among women. These examples challenge the notion that obesity is simply a result of overconsumption and lack of physical activity.
The Failure of Conventional Approaches
Taubes argues that the prevailing explanatory models for obesity have failed to stop the obesity epidemic or explain why, among people who share similar lifestyles, some are fat and others are not. This failure suggests that our understanding of obesity and weight gain is fundamentally flawed.
The author encourages readers to question the established views on the subject, especially if they have struggled with weight loss despite following conventional advice. This critical examination of widely accepted beliefs sets the stage for Taubes to present his alternative explanation for why we get fat.
The Fat Fallacy
Another misconception that Taubes addresses is the idea that eating fat makes us fat. He traces this belief back to the 1950s and 1960s when there was a significant rise in heart disease cases. During this time, the medical community began to link fatty foods with obesity, clogged arteries, and heart disease.
This shift in thinking led to widespread warnings about the dangers of a high-fat diet. The logic seemed simple and appealing: fat in food makes us fat, which then leads to heart disease. This belief became so entrenched that it influenced an entire generation of medical students and shaped public health policy for decades.
However, Taubes points out that despite the push for low-fat diets, people didn't lose weight. In fact, obesity rates continued to rise, along with cases of heart disease. This paradox suggests that the fat-focused approach to weight loss and health may be fundamentally flawed.
The Exercise Myth
Taubes also challenges the common belief that lack of exercise is a primary cause of obesity. He argues that the relationship between exercise and weight is more complex than commonly thought.
The author suggests that lethargy in overweight individuals is not a cause of their condition, but rather a symptom. He compares this to children going through growth spurts, who often become less active because their bodies are using energy for growth. Similarly, Taubes argues, overweight people may become less active because their bodies are directing energy towards fat storage.
Furthermore, Taubes points out that increasing exercise while reducing calorie intake can be counterproductive. As we exercise more, our bodies require more energy to function, which can increase appetite. This can make it even more challenging for people to maintain a calorie deficit.
To support his argument, Taubes cites a 1983 study of Mexican immigrants in southern Texas. Despite living in poverty and performing hard labor, about 40% of these individuals were overweight. This example challenges the notion that high levels of physical activity necessarily lead to weight loss.
The Real Culprit: Carbohydrates and Insulin
The Role of Insulin
After dismantling the conventional wisdom about obesity, Taubes presents his alternative explanation. At the heart of his argument is the hormone insulin and its relationship with carbohydrates.
Insulin plays a crucial role in our metabolism, regulating how our bodies process carbohydrates, fats, and proteins. When we eat carbohydrates, our blood sugar levels rise, prompting the release of insulin. Insulin helps transfer energy into muscle tissue for burning, but it also stimulates fatty tissue to store excess energy.
Taubes explains that when we eat a meal, especially one high in carbohydrates, our bodies prioritize burning the energy from carbohydrates. This is because high blood sugar levels can be harmful to cells, so the body needs to quickly lower blood sugar by burning off the glucose. The amount of insulin released depends on the amount of carbohydrates consumed.
Any excess energy, whether from carbohydrates, proteins, or fats, is stored as fat for potential future use when external energy supply might be low. However, foods rich in carbohydrates, such as sweets, bread, potatoes, pasta, and rice, cause a rapid increase in blood sugar, leading to a significant insulin response. The higher the insulin level, the more strongly the body is stimulated to form fatty deposits.
Therefore, Taubes argues, carbohydrates have the most significant influence on the mechanism that regulates fat accumulation. In essence, it's carbohydrates, not fats or overall calorie intake, that make us fat.
Obesity as a Growth Disorder
Taubes presents a paradigm shift in how we should view obesity. Instead of seeing it as a result of overeating and lack of exercise, he suggests we should view it as a growth disorder, similar to how we view other forms of tissue growth in the body.
When tissues expand, whether it's a tumor forming or a child growing taller, we call this "growth," and we understand that these changes are based on complex processes controlled by hormones. No one would say that a child grew taller because they ate too much. Instead, we understand that their hormonally regulated growth requires a lot of energy, which makes them hungry.
Taubes argues that we should think about obesity in the same way. The growth of fat cells is not simply a result of eating too much, but rather a consequence of hormonal imbalances, particularly involving insulin. Just as in the case of a tumor, the growth of fat cells can be impaired because our bodies respond to high levels of blood sugar by producing excessive insulin.
This perspective shift helps explain why overweight people often feel hungrier and more lethargic. As their fat cells grow, they consume more energy, leading to increased hunger – just like a child going through a growth spurt.
By recognizing obesity as a consequence of a biological growth process, we can see that gluttony and laziness are not the causes of weight gain, but rather symptoms of a growth disorder. This understanding is crucial for developing more effective approaches to weight management.
The Evolutionary Mismatch
Taubes delves into the evolutionary aspects of our diet to explain why carbohydrates, particularly in the quantities and types we consume today, are so problematic for our health.
He points out that carbohydrates, which make up a significant part of our modern diet, are a relatively new addition to human nutrition in evolutionary terms. Humans have been on Earth for about 2.5 million years, but we only began eating flour around 12,000 years ago with the spread of agriculture. White flour and white sugar only became significant parts of the human diet at the end of the 19th century.
This means that the era of carbohydrate-rich food is but a blink of an eye in human evolutionary history. Taubes argues that it's unlikely we've developed genetic adaptations to handle these quickly digestible carbohydrates in such a short period.
Before the spread of agriculture, our ancestors lived as hunters and gatherers, preferring fatty meats to quell their hunger. Taubes cites studies of present-day hunting and gathering cultures that have been isolated from modern civilization. These groups' diets consist largely of fish and meat, with some surviving without eating any vegetables, fruits, or grains at all – the polar opposite of our modern diet, where carbohydrates make up about two-thirds of our caloric intake.
This evolutionary mismatch between our bodies' adaptations and our modern diet, Taubes argues, is at the root of our obesity epidemic. Our bodies simply aren't equipped to handle the quantity and type of carbohydrates that have become ubiquitous in our diets.
The Health Consequences of Carbohydrates
Taubes doesn't just argue that carbohydrates make us fat – he also links them to a host of other health problems. He explains that regularly exposing our bodies to large amounts of carbohydrates over a long period can disturb the signaling function of insulin.
The mechanism that controls our metabolism is incredibly sensitive, and it can be thrown out of balance by the high-carbohydrate diets that are common today. This imbalance can result in an oversupply of insulin, which not only leads to weight gain but also increases susceptibility to diseases like diabetes and high blood pressure.
Taubes points out that these "Western diseases" suddenly appear in almost every culture when it first comes into contact with Western foods. He cites examples of immigrant populations whose disease rates change to mirror those of their new country within a generation or two, regardless of their ethnicity or the specific disease in question.
For instance, breast cancer rates among Japanese women living in Japan are relatively low. However, the breast cancer rates of the descendants of Japanese women who immigrated to the US match those of other women in the US. This pattern is seen across various immigrant groups and diseases, suggesting that something in the Western diet – which Taubes argues is primarily the high carbohydrate content – is responsible for these health changes.
By linking carbohydrates not just to obesity but to a range of other health issues, Taubes strengthens his argument for a fundamental reevaluation of our dietary guidelines and approaches to public health.
The Failure of Conventional Diets
The Problem with Low-Calorie Diets
Taubes dedicates significant attention to explaining why conventional low-calorie diets are ineffective and potentially harmful. These diets, which focus on reducing overall calorie intake, are ubiquitous in the weight loss industry. However, Taubes argues that they are fundamentally flawed.
While low-calorie diets can lead to short-term weight loss, they almost always fail in the long term. The main issue, according to Taubes, is that these diets require constant effort to maintain the lower weight. This is because low-calorie diets essentially starve the body, depriving it of not just calories but also essential nutrients.
Taubes uses the example of a person who reduces their caloric intake by 20% across all foods. This person would not only be consuming 20% fewer calories but also 20% fewer vitamins and minerals. This nutrient deprivation can have negative health consequences and make it difficult to sustain the diet long-term.
Moreover, when people return to their normal eating habits after a period of calorie restriction, they often experience the "yo-yo effect," regaining the lost weight and sometimes more. This is because the body, having been deprived, is primed to store energy when it becomes available again.
To illustrate the ineffectiveness of low-calorie diets, Taubes cites a large-scale experiment conducted in the US in the early 1990s. Over eight years, 20,000 female participants reduced their daily calorie intake by 360 calories. They ate foods considered healthy: high in fiber, fruits, and vegetables, and low in fat. Despite these efforts, the women only lost an average of two pounds over the entire period. Even more concerning, many of them gained weight around their midsections, indicating a loss of muscle mass rather than fat.
Taubes argues that the widespread failure of low-calorie diets should raise serious doubts about their efficacy. He points out that most overweight people have already tried simply eating less, yet most of them remain overweight. This persistent failure, he suggests, should prompt us to question the fundamental assumptions behind the calorie-restriction approach to weight loss.
The Metabolic Consequences of Dieting
Taubes explains that low-calorie diets can have negative impacts on metabolism. When we significantly reduce our calorie intake, our bodies interpret this as a sign of food scarcity and respond by slowing down metabolic processes to conserve energy.
This metabolic slowdown can make it increasingly difficult to lose weight as the diet progresses. It can also lead to feelings of fatigue, irritability, and constant hunger, making the diet hard to sustain. Moreover, once the diet ends and normal eating resumes, the slowed metabolism can cause rapid weight regain.
Taubes argues that this metabolic adaptation is one of the key reasons why low-calorie diets are ineffective for long-term weight management. Instead of addressing the root cause of weight gain – which he believes is hormonal imbalance caused by carbohydrate consumption – these diets create a cycle of weight loss and regain that can be frustrating and demoralizing for dieters.
Factors Influencing Weight Gain
Genetic Predisposition
While Taubes emphasizes the role of diet, particularly carbohydrate intake, in weight gain, he also acknowledges the importance of genetic factors. He explains that our genes play a significant role in determining whether we put on weight, and if so, when and where we put it on.
Genetic factors influence how effectively our muscles burn energy and how quickly we store energy for emergencies. This means that some people are simply more prone to gaining weight than others. Taubes points out that while some individuals seem to gain weight just by thinking about sweets, others can indulge in high-calorie foods without apparent consequences.
This genetic predisposition helps explain why obesity often runs in families and why some people struggle with weight gain despite following similar diets and exercise routines as their naturally slim counterparts. However, Taubes is careful to note that genetic predisposition doesn't mean obesity is inevitable – it simply means that some people may need to be more vigilant about their carbohydrate intake than others.
Age and Insulin Sensitivity
Another factor that Taubes discusses is the role of age in weight gain. He explains that as we get older, our bodies tend to become more resistant to insulin, which can lead to increased fat storage.
Insulin resistance develops over time as our bodies are repeatedly exposed to high levels of insulin resulting from carbohydrate-rich diets. The longer and more intensely we generate high insulin levels, the more resistant our muscle tissue becomes to insulin's effects. This resistance inhibits our bodies from efficiently burning energy.
In response to this resistance, the body produces even more insulin to lower blood sugar levels, creating a vicious cycle that advances the growth of fat cells. This insulin resistance typically appears first in muscle cells and only later, if at all, in fat tissues.
Taubes points out that this is why older people are generally more prone to being overweight, even if they never had weight issues in their youth. The common wisdom attributes this tendency to a slowing metabolism, but Taubes argues that increased insulin resistance is a more accurate explanation.
Furthermore, he suggests that by consuming high doses of carbohydrates throughout our lives, we reinforce this process, boosting our insulin resistance and making it increasingly difficult to maintain a healthy weight as we age.
The Role of Nutrition
While genetic predisposition and age are important factors, Taubes maintains that nutrition plays the most crucial role in determining whether we become overweight. Specifically, he argues that the type and quantity of carbohydrates we consume have the most significant impact on our weight.
Taubes explains that different types of carbohydrates influence our blood sugar and insulin levels in varying ways. Generally, the sweeter the food, the more likely it is to cause weight gain. Foods like sweets, cereal products, starchy foods, and sugar-containing drinks are highly concentrated sources of energy that can cause rapid spikes in blood sugar and insulin levels.
On the other hand, the carbohydrates found in most vegetables are linked to indigestible fibers, which have a smaller impact on blood sugar and insulin release. This is why Taubes advocates for a diet that eliminates or severely restricts refined carbohydrates while allowing for the consumption of fibrous vegetables.
By understanding these factors – genetic predisposition, age-related changes in insulin sensitivity, and the crucial role of nutrition – Taubes provides a comprehensive framework for understanding why we get fat. This understanding, he argues, is essential for developing effective strategies for weight management and overall health.
The Case for Low-Carbohydrate Diets
Challenging the Skepticism
Taubes dedicates a significant portion of the book to making a case for low-carbohydrate diets, which he believes are unfairly maligned by many health professionals. He argues that the widespread skepticism towards these diets is based on flawed assumptions and a misunderstanding of how our bodies process different nutrients.
According to Taubes, the resistance to low-carbohydrate diets is rooted in three main assumptions:
- It's impossible to lose weight without burning more energy than you take in.
- Carbohydrates are essential for a healthy diet.
- Replacing carbohydrates with fats leads to weight gain and increased risk of heart disease.
Taubes systematically challenges each of these assumptions. He points out that the first assumption ignores the hormonal effects of different foods on our metabolism. The second overlooks the fact that there are no essential carbohydrates (unlike essential fats and proteins) that our bodies can't produce on their own. The third, he argues, is based on the flawed logic that dietary fat leads to body fat and heart disease – a notion he's already dismantled earlier in the book.
The Benefits of Low-Carb Diets
Taubes presents several arguments in favor of low-carbohydrate diets:
Nutrient Density: He points out that meat is rich in essential vitamins and minerals. Moreover, carbohydrates can be replaced with vegetables, which are also nutrient-dense. This contrasts with low-calorie diets, which often lead to overall nutrient deficiencies.
Historical Evidence: Taubes cites examples of traditional cultures that thrived on high-fat, low-carbohydrate diets. These populations, he notes, were free from obesity and many of the chronic diseases that plague modern societies.
Insulin Control: By reducing carbohydrate intake, these diets help maintain lower and more stable insulin levels. This, according to Taubes, is key to preventing fat storage and promoting fat burning.
Satiety: High-fat, low-carb diets often lead to greater feelings of fullness and satisfaction, making it easier for people to naturally reduce their calorie intake without feeling deprived.
Metabolic Advantages: Taubes argues that low-carb diets can lead to metabolic advantages, potentially allowing people to eat more calories while still losing weight compared to low-fat, high-carb diets.
Addressing Health Concerns
Taubes also tackles the common health concerns associated with low-carbohydrate diets, particularly the fear that they may increase the risk of heart disease due to their higher fat content.
He argues that this fear is based on the mistaken belief that dietary fat leads to body fat and heart disease. Taubes points out that if fat were the culprit in heart disease, we'd see an paradoxical increase in heart disease risk as people lost weight on low-carb diets – which is not the case.
Moreover, he cites studies showing that low-carb diets can actually improve various markers of heart health, including reducing triglycerides and increasing HDL (good) cholesterol.
Taubes also addresses concerns about nutrient deficiencies on low-carb diets. He argues that a well-formulated low-carb diet that includes a variety of meats, eggs, and green vegetables can provide all necessary nutrients. In fact, he suggests that such a diet may be more nutrient-dense than the standard high-carb, low-fat diet recommended by many health authorities.
Practical Advice for Weight Management
Eliminating Carbohydrates
Based on his research and arguments, Taubes provides practical advice for those looking to lose weight or maintain a healthy weight. His primary recommendation is simple: significantly reduce or eliminate carbohydrate intake, especially refined and easily digestible carbs.
Taubes argues that this approach is the most effective way to control insulin levels, which he sees as the key to managing weight. By keeping insulin levels low and stable, the body is less likely to store fat and more likely to burn stored fat for energy.
He recommends avoiding or severely limiting foods such as:
- Sweets and sugary foods
- Bread, pasta, and other grain-based products
- Starchy vegetables like potatoes
- Sugary drinks, including fruit juices
- Alcoholic beverages
Instead, Taubes suggests focusing on foods that have minimal impact on blood sugar and insulin levels, such as:
- Meats and fish
- Eggs
- Non-starchy vegetables
- Healthy fats like olive oil, avocados, and nuts
Individualized Approach
While Taubes is a strong advocate for low-carbohydrate diets, he acknowledges that the degree of carbohydrate restriction necessary may vary from person to person. He explains that not everyone is equally sensitive to carbohydrates, and thus not everyone needs to follow an extremely low-carb diet to maintain a healthy weight.
For those who are overweight or prone to easy weight gain, Taubes suggests a more strict approach to carbohydrate limitation. These individuals, he argues, are likely more sensitive to the effects of carbohydrates on insulin levels and thus need to be more vigilant in their dietary choices.
On the other hand, those who have never struggled with weight issues may be able to include more carbohydrates in their diet without negative consequences. However, Taubes still advises caution with refined and easily digestible carbs, as these can lead to health issues beyond just weight gain.
Long-Term Sustainability
Taubes emphasizes that his recommendations are not just for short-term weight loss, but for long-term health and weight management. He argues that viewing a low-carb approach as a "diet" in the traditional sense – a temporary change in eating habits – is misguided.
Instead, he suggests that people should view this as a permanent shift in how they eat and think about food. This shift, he argues, is necessary not just for weight loss, but for maintaining weight loss and overall health in the long term.
Taubes acknowledges that this can be challenging in a food environment dominated by carbohydrate-rich options. However, he argues that understanding the science behind why carbs lead to weight gain can help motivate people to make and stick to these changes.
Conclusion
In "Why We Get Fat," Gary Taubes presents a compelling alternative to the conventional wisdom about obesity and weight gain. He challenges deeply ingrained beliefs about calories, fat, and exercise, and offers a new paradigm centered on the role of carbohydrates and insulin in fat storage.
Taubes argues that the obesity epidemic is not a result of gluttony or sloth, but rather a consequence of our modern diet's heavy reliance on carbohydrates, particularly refined sugars and starches. He presents a wealth of scientific evidence and historical examples to support his case, drawing from fields as diverse as endocrinology, genetics, and anthropology.
The book's central message is that to lose weight and keep it off, or to avoid getting fat in the first place, we need to significantly reduce our carbohydrate intake. Taubes contends that this approach is not only more effective for weight management but also healthier overall, potentially reducing the risk of various chronic diseases associated with the Western diet.
However, Taubes is careful to note that the degree of carbohydrate restriction necessary may vary from person to person, depending on factors like genetic predisposition and insulin sensitivity. He advocates for an individualized approach to nutrition, based on understanding one's own body and its responses to different foods.
While Taubes' ideas remain controversial in some circles, "Why We Get Fat" provides a thought-provoking challenge to conventional nutritional wisdom. It encourages readers to question long-held beliefs about diet and health, and to consider a different approach to weight management and overall wellness.
Ultimately, the book's value lies not just in its specific dietary recommendations, but in its broader message about the importance of critical thinking in matters of health and nutrition. By encouraging readers to look beyond simplistic explanations and to consider the complex interplay of hormones, genetics, and diet, Taubes provides a framework for a more nuanced and potentially more effective approach to health and weight management.
Whether or not readers fully embrace Taubes' low-carb paradigm, "Why We Get Fat" offers valuable insights into the science of nutrition and weight gain. It serves as a reminder that in the field of health and nutrition, what we think we know is often less certain than we believe, and that being open to new ideas and evidence is crucial for progress in both personal and public health.