As a food policy dork and avid reader of Marion Nestle's blog Food Politics, I have been eagerly anticipating the release of her newest book. While the rest of the world waited with bated breath for the opening of The Hunger Games, I watched for the delivery of Why Calories Count: From Science to Politics, co-authored by Nestle and Malden Nesheim. And with its careful research, lighthearted tone, and eye-opening research, this book certainly lived up to my expectations.
The book's central purpose is to examine the calorie: its conception, its perception, and its influence on our eating culture. Since the 1800s, foods have been identified as part of three major categories: proteins, fats, and carbohydrates. The appropriate nutritional balance of these three types of calorie has been the topic of heated debate ever since. The calorie was given its current importance by Wilbur O. Atwater, "the father of modern nutrition science in the United States." Atwater's contributions included determining the number of calories per gram of proteins, fats, and carbohydrates. These numbers—4, 9, and 4 respectively—have stood the test of time. That Atwater correctly determined these values with his relatively primitive bomb calorimeter and scrupulous data collection is certainly admirable.
Nestle and Nesheim are nutritionists, and their work is heavily based in clinical studies on caloric intake and expenditure. But rather than give the book an academic weight, this data provides a refreshingly honest and analytical approach to diet. The authors spend much of the first half of the book explaining the physiological processes of digestion and metabolization of calories. They use this information as a framework for understanding the impacts that fad diets, crash dieting, and overeating have on our bodies and metabolisms.
It was particularly interesting to read about the shaky science and politics behind calorie estimates and recommendations. For instance, most studies related to calorie intake and weight loss depend on self-reporting, a notoriously unreliable and inconsistent source of data. Researchers can therefore make all kinds of claims based in this ambiguous information about what people are eating, and it becomes nearly impossible to estimate the "average" American diet. And of course, there are all sorts of messy politics surrounding nutrition facts labels, junk food regulation and production, and a changing food culture that encourages snacking and eating outside the home.
The authors' central theme seems obvious from the title: calories do count. What this means in practice is that calorie intake and expenditure is what regulates body weight, rather than excluding specific items from the diet (low-carb, low-fat, etc.). They take particular aim at Gary Taubes, whose "reductionist view" emphasizes that carbohydrates are the primary driver behind weight gain. While they support reducing sugar intake and limiting processed carbs, Nestle and Nesheim stand their ground that the type of calories consumed is less important than the amount.
Which leads us to an almost frustratingly simple recommendation: eat less and exercise more to lose weight and keep it off. Where have I heard that before? Sure, it's easy to roll your eyes at this conclusion. But so few of us actually subscribe to a lower calorie, higher activity lifestyle when looking to drop a few pounds. It's impossible to ignore the research and analysis that Nestle and Nesheim put forth. Their weight loss suggestions at the end of the book are neither prescriptive nor lax. Get organized and motivated about your diet plan; be aware of calories but don't count them obsessively; don't snack; eat what you like; move at consistent intervals throughout the day. Just like the doctor ordered—and has probably been ordering for decades.
About the Author: A student in Providence, Rhode Island, Leah Douglas loves learning about, talking about, reading about, and consuming food. Her work has also been featured in Rhode Island Monthly Magazine.