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Book Review: Good Calories, Bad Calories

by | Jan 6, 2010

good calories bad calories cover

Good nutrition advice is not easy to come by, but we have to start somewhere.

It is probably obvious to most of you that public education on diet and health is vastly inadequate. We learn virtually nothing in school, and what they do manage to pass on is less-than-useful or just simply wrong.

Advice changes from year to year, sometimes drastically.

Everyone claims to be a nutrition expert, but very few people are actually trained enough to understand the complex and sometimes contradictory findings made by scientists in the field.

But although there are few sources you can trust, some books do stand out as valuable for understanding the basics of health and nutrition. Good Calories, Bad Calories by Gary Taubes is by far the most thorough I’ve found, and is essential reading for anyone who has an honest desire or need to understand how diet impacts health.

Taubes makes a detailed and compelling case that refined carbohydrates are the primary cause of weight gain and “diseases of civilization” such as heart disease, hypertension and diabetes. In my view, any honest and opened-minded scientist would have to largely agree with him.

GradeAGood Calories, Bad Calories is 468 pages and contains over 100 additional pages of references, which is nothing short of astonishing. Taubes explores every aspect of the science behind weight control including the most puzzling and frequently ignored evidence, which he argues is the most important.

Scientists depend on statistics, but have a tendency to ignore outliers which can make data difficult to interpret. Taubes instead points to these anomalies as evidence of flawed or incomplete theories, and suggests that isolated populations (outliers) such as the Inuit and Maasai tribes actually help the most in explaining diet-related health patterns.

Taubes argues extensively (sometimes a bit heavy-handedly) against lazy scientific thinking that relies too heavily on conventional wisdom and the appeal of simple ideas. This point is a major theme of the book and is exemplified by chapter 2, “The Inadequacy of Lesser Evidence.” He goes to great lengths to explain how our tendency not to scrutinize established theories breeds scientific closed-mindedness and can perpetuate flawed ideas for decades.

Ultimately Taubes uses this argument to directly challenge one of the most prevailing health theories in Western civilization: the cholesterol–heart disease hypothesis.

Taubes provides hundreds of pages of data and analysis to make the point that total cholesterol is not a good predictor of heart disease or mortality. Specifically LDL cholesterol is only loosely associated with heart disease (at best) and HDL cholesterol (the higher the better) is a much better indication of vascular health. (Read more: How To Raise Your HDL Cholesterol)

Once this basic premise of health is thrown into question, Taubes carries you through the logic of why a high-fat diet cannot be responsible for heart disease (remember the Inuit) and instead presents why quickly digesting carbohydrates are the most likely culprit.

Fundamental to this argument is the tie between heart disease and type 2 diabetes (along with other “disease of civilization” or metabolic syndrome), which are both inextricably linked to carbohydrate consumption. The logical conclusion from his analysis is that all calories are not created equal, despite what we are told daily by the nutrition community and the media. Understanding the logic behind this argument can fundamentally change the way you approach food and is the best reason to read Good Calories, Bad Calories.

Despite this, Taubes’ book is rarely the first I recommend to people who come to me for nutrition advice. There are a few reasons for this, but the main one is that Good Calories, Bad Calories is not an easy read. I’m a scientist and nutrition data junkie, and this book still took me months to get through (I normally read 4-5 per month). For your average eater, a book like this can quickly become a burden and many people will give up before getting to the good part (about half way through it starts to pick up substantially).

In the first few chapters I was put off by the book’s almost defensive tone. A large part of the first section is dedicated to discrediting the character of a pioneering scientist and father of the dietary fat–heart disease hypothesis, Ancel Keyes. Presumably this depiction is intended as background so the reader understands why Keyes so aggressively disseminates a theory that isn’t fully proven. However, I found the extensive character attack unbecoming for a book espousing science and experimental data, and it seemed unnecessary.

Another reason I resist recommending this book as nutrition advice is that it doesn’t offer much in the way of actual advice. Taubes certainly provides compelling evidence that carbohydrates are best avoided and that dietary fat is safer than presumed, but how much of this knowledge can be translated directly to daily life isn’t clear. For practical advice, I prefer Michael Pollan’s In Defense of Food (based largely on the same data).

Scientifically I also have a few issues with Good Calories, Bad Calories. First, the vast majority of the experiments Taubes cites are early diet studies, many from the turn of the century. While these experiments are clearly important, most of them do not reflect long-term (more than 6 months), real life dietary habits. These studies were also almost entirely dependent upon self-reported dietary intake, which is known to be quite inaccurate.

Much of Taubes’ argument about calories is based on the premise that overweight people eat the same amount or less than lean people. This was once thought to be the case, but recently more thorough studies have shown that overweight and obese people do indeed eat more. The problem is that all people (both lean and obese) are poor judges of food intake, and this discrepancy is largest with the biggest meals consumed. This means people who eat the largest meals tend to underestimate their calories the most, and meal size is correlated with body weight.

This does not mean that I disagree entirely with Taubes’ theory on calories. I was more convinced by the rodent studies he presented where dietary intake was tightly controlled and measured. In some of these, obese animals did seem to eat the same or less than leaner animals (always be careful reading too much into rodent data). Interestingly, the difference in body weight was always accounted for by differences in physical activity, a point I find extremely fascinating.

Since mice obviously do not exercise for the purpose of fitting into skinny jeans, the activity differences observed between obese and lean mice is clearly a fundamental change in metabolism (balance of energy use and intake). If this is true and can be manipulated by diet composition rather than voluntary exercise (which causes overeating), as Taubes suggests, this has tremendous implications for treating obesity and disease through selective diets and metabolic manipulation. I think Taubes makes a strong case for this and it is a point that should be taken very seriously by the scientific community.

My final issue with the book is how the data was presented to seemingly support a diet of almost entirely meat and animal products. While Taubes does not come out directly and say “the healthiest diet is 100% meat,” people without a knack for thinking like a scientist can easily come away with this impression (I’ve seen it).

[note: My guess is this is why I get so many emails from people asking me to help them choose between this book and The China Study (click for review), which both come off as scientific but also as diametric opposites. Personally I do not see a huge conflict between the data presented in the two books, but see it as an issue of interpretation. On this point, my vote goes to Taubes for his superior logic and reasoning.]

My own interpretation of the data presented in this book, however, is not that all carbohydrates are the enemy, but rather that quickly digesting (processed) carbs are the real problem. Taubes never refutes this as far as I could tell, though he does glorify meat-based diets (again remember the Inuit) as the best for optimal nutrition, while belittling the case for a balanced diet. But there is an important difference between saying “meat is good” and “all plants are bad,” which he never directly asserts.

Yet many people still take from this book that a protein and fat-based diet is the healthiest option, which is a flawed interpretation. Vegan diets with no animal products whatsoever can be perfectly healthy, as can largely meat-based diets, and that both are perfectly legitimate is a point that is easily forgotten by the end of Good Calories, Bad Calories.

But while the value of eating plants is an important question for the practical implications of Taubes’ theory of calories, it is not fundamental it.

Summary

Taubes’ meticulous research and overly-thorough analysis represent both the strengths and weaknesses of this book. His case for the role of metabolism in health and obesity, and against the dogma that “a calorie is a calorie” is a tremendous contribution to the field of nutrition. However, this depth can make Good Calories, Bad Calories cumbersome and difficult to read.

Final Grade: A

What did you think of Good Calories, Bad Calories?


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Antioxidant Supplements May Block Some Benefits of Exercise

by | May 13, 2009
Romanesco Broccoli In A Beaker

Romanesco Broccoli in a Beaker

One of the most consistent themes of nutrition science is that vitamin supplements (pills, powders, liquids, etc.) are almost never able to mimic the beneficial effects of foods that contain the same vitamins. Now new evidence suggests that high doses of these antioxidant supplements–but not whole foods containing them–may actually block the beneficial effects of exercise on insulin sensitivity and metabolism.

Exercise has countless benefits for people of all levels of fitness. One of the most important of these is its ability to improve insulin sensitivity and increase metabolism. For this reason, exercise is considered among the most effective ways to protect against type 2 diabetes.

One of the byproducts of exercise, however, is the production of free radicals that results from the breakdown of oxygen in the muscles. These reactive oxygen molecules can damage cells and DNA, and are implicated in many chronic diseases. Since antioxidants can easily neutralize these reactive oxygen molecules, it has been assumed that antioxidants such as vitamins C and E could only benefit the body.

A new study published in the Proceedings of the National Academy of Sciences suggests that rather than help protect against oxidative damage from exercise, high doses of antioxidant supplements may actually hinder the body’s natural protection against oxidative damage and block exercise-induced metabolic benefits.

In the study, human subjects were given either placebo or 500 mg vitamin C twice per day and 400 IU vitamin E. They were then trained in both cardio and strength training workouts at the gym for 5 consecutive weekdays, 4 weeks in a row. This trial was performed on both previously trained and untrained individuals.

Metabolic rates were tested by blood sample both before the trial and after 1 and 4 weeks of training. Muscle biopsies were taken both before and after the trial for all participants. Several measures of metabolism and insulin sensitivity were measured including plasma glucose concentrations, plasma insulin concentrations, maximal oxygen uptake (VO2 max), as well as several molecular markers in muscle that are linked to insulin sensitivity and are known to promote the body’s natural defense against oxidative damage.

The researchers found that exercise improved measures of insulin sensitivity in all individuals except those given antioxidant supplements. Also, molecules that protect against oxidative damage are upregulated in response to training, but not when antioxidants are administered.

Previous studies suggest that the body’s natural defenses against oxidative damage require activation by a small amount of reactive oxygen chemicals in the body. These same chemicals have been shown to mediate insulin sensitivity in muscles, and in this study both were shown to be blocked by high antioxidant administration.

The researchers suggest that small doses of reactive oxygen molecules such as the amounts produced by exercise are necessary to induce the body’s natural defense against oxidative damage, and that this process is essential for mediating exercise-induced insulin sensitivity. If this is true it could mean that some (but not all) of the metabolic benefits of exercise could be limited by taking high doses of vitamin supplements. This may be particularly important to individuals at high risk for type 2 diabetes.

Interestingly, foods that contain high levels of these antioxidants have previously been shown to be protective against type 2 diabetes. Although the reason for this is still unknown, the authors suggest the benefit is unlikely due to the antioxidant content of the foods and may depend on other factors.

Even if we do not understand the reason vegetables and fruits are the best source of nutrition, we can still enjoy all their benefits. If you choose to continue taking vitamin supplements, it is advisable to stick to a basic multivitamin that does not contain megadoses of one particular nutrient.

Do you take vitamin supplements? Why? How much do you take?
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