Calories cannot be seen, smelled, or tasted, and yet they are vital to life. Why Calories Count: From Science to Politics takes a look at how our understanding of calories has developed over the years and how people today understand them.
Food Politics author Marion Nestle co-authored Why Calories Count with Malden Nesheim, both professors of nutrition. The two of them have written a detailed, but easy-to-understand book on calories – how science came to understand and measure calories, what they are in food and what they do in the human body, and the role calories play in our political and cultural environment.
What Why Calories Count is not – it’s not a diet book. There are no menus, food lists, ideal weight charts, or anything like that.
The book starts with the definition of a calorie:
One calorie is the amount of heat energy needed to raise the temperature of one gram of water by one degree centigrade, from 14.5 degrees to 15.5 degrees, at one unit of atmospheric pressure.
This is not terribly useful for the average American. We don’t think in terms of grams or centigrade and certainly not in terms of units of atmospheric pressure. Don’t worry about that. The authors quickly make the calorie relatable in ordinary terms and they keep it interesting.
Science of Calories
Just a few pages later, we’re treated to the history of the calorie, starting with Hippocrates (around 400 BC) through to the Enlightenment and modern science.
I was absolutely fascinated by the history of the calorimeter. I used one in high school chemistry, but it was very small and I never really understood how it related to the use of calories in the body. Well, now I do. Did you know scientists in the 1800s built calorimeters large enough to house a person for several days?
From that foundational understanding of what calories are and how they are measured, we can understand how the body breaks down the calories in food and what those calories are used for in the body. A range of factors come into play in how individual bodies use calories – age, sex, genetics, and more.
Politics of Calories
Through all of the science, the authors include the effects of the political climate of the time. In our own time, there have been agricultural policies and a history of regulating and deregulating that has changed nutrition labels over time and brought us to our current situation of encouraging Americans to eat more than we really need.
Labels have been used to inform us, but also to market to us. The listing of carbohydrates, fats, and proteins on the nutrition labels has helped corporations market foods to Americans according to the latest fads in diet books. Nutritionists and involved consumers like the readers of Eat Drink Better have tried to limit the health claims companies can make, but there’s always a push and pull between information and marketing.
Why don’t alcoholic beverages have calories listed on the label? That’s a tangled web of an explanation that involves Prohibition, low-fat and low-carb diet trends, and other things. As with every other calorie-related topic in this book, Nestle and Nesheim lead us through the explanation in a thorough and thoroughly interesting manner.
I recommend this book for anyone who wants to understand the science of food and the body as well as the politics of what and how food makes it to our plates.