The Truth About Calories

on Monday, June 13, 2011

Clint Carter of Men's Health has written recently a piece that purports to debunk a few myths about calories. I thought it might be helpful to debunk the debunker, as it were, and make my small effort to stop the promulgation of "bro science," especially when it makes to to publication by Yahoo Health and Men's Health at the same time.
Myth #1: Calories Fuel Our Bodies 
Actually, they don't 
A calorie is simply a unit of measurement for heat; in the early 19th century, it was used to explain the theory of heat conservation and steam engines. The term entered the food world around 1890, when the USDA appropriated it for a report on nutrition. Specifically, a calorie was defined as the unit of heat required to raise 1 gram of water 1 degree Celsius.
To apply this concept to foods like sandwiches, scientists used to set food on fire (really!) and then gauge how well the flaming sample warmed a water bath. The warmer the water, the more calories the food contained. (Today, a food's calorie count is estimated from its carbohydrate, protein, and fat content.) In the calorie's leap to nutrition, its definition evolved. The calorie we now see cited on nutrition labels is the amount of heat required to raise 1 kilogram of water by 1 degree Celsius.
Here's the problem: Your body isn't a steam engine. Instead of heat, it runs on chemical energy, fueled by the oxidation of carbohydrates, fat, and protein that occurs in your cells' mitochondria. "You could say mitochondria are like small power plants," says Maciej Buchowski, Ph.D., a research professor of medicine at Vanderbilt University medical center. "Instead of one central plant, you have several billion, so it's more efficient.

Stating that "calories don't fuel our bodies," is just laughably wrong. Calories are a measurement of stored energy. They can be applied to anything that can be burned -- including food, fire wood, and gasoline, and our body pulls energy from food to keep the body running. Calories are a direct measurement of the potential energy in each food, and to state that the calorie content of food does not matter is ridiculous. It doesn't matter if the body "chemically oxidizes" food to yield energy. That process is still a type of "burning." A campfire can be described as "oxidizing" wood.

Later, he states that the body has to spend more energy burning proteins, and has trouble accessing fuel when it is mixed with fiber, which is correct, but her numbers are exaggerated estimates. The body is tremendously efficient in sucking every last calorie from its food, unless the body is diseased or sick.

If I offer 2,000 gallons of gasoline to you, does it matter if you burn them all in one car or 100 cars? The result is the same; the cars will travel the same distance, net.

In fact, the Ph.D's statement is backwards. The more power plants we have the less efficient the power generation becomes. Each one of those cars has to warm up to peak efficiency. This is why we have central power stations -- it is more efficient. Economies of scale work for coal burning and food burning in your body.

In any event, the number of "power plants" doesn't matter. The fuel entering the body, and the body's ability to pull energy from it is all that matters. Don't forget that a car "oxidizes" gasoline to produce power for the car. Calling it oxidization doesn't mean it isn't burning the food.

Myth #2: All Calories Are Created Equal 
Not exactly
Our fuel comes from three sources: protein, carbohydrates, and fat. "They're handled by the body differently," says Alan Aragon, M.S., a Men's Health nutrition advisor. So that old "calories in, calories out" formula can be misleading, he says. "Carbohydrates, protein, and fat have different effects on the equation."
Example: For every 100 carbohydrate calories you consume, your body expends 5 to 10 in digestion. With fats, you expend slightly less (although thin people seem to break down more fat than heavy people do). The calorie-burn champion is protein: For every 100 protein calories you consume, your body needs 20 to 30 for digestion, Buchowski says. Carbohydrates and fat give up their calories easily: They're built to supply quick energy. In effect, carbs and fat yield more usable energy than protein does.

Indeed, the body has more trouble generating energy from different types of food, be it protein, carbohydrates, fats or alcohol. A lot of work has been done on this topic, and the calories we see on food labels take this information into consideration. The calories listed on the label will be a good approximation of the amount of energy the body will be able to pull from the food, which will be different from the amount a fire can get fromt he same food. To imply that 100 calories of protein is going to yield less than 100 calories of energy for an average human body is absolutely incorrect.
Myth #3: A Calorie Ingested is a Calorie Digested 
It's not that simple
Just because the food is swallowed doesn't mean it will be digested. It passes through your stomach and then reaches your small intestine, which slurps up all the nutrients it can through its spongy walls. But 5 to 10 percent of calories slide through unabsorbed. Fat digestion is relatively efficient—fat easily enters your intestinal walls. As for protein, animal sources are more digestible than plant sources, so a top sirloin's protein will be better absorbed than tofu's.
Different carbs are processed at different rates, too: Glucose and starch are rapidly absorbed, while fiber dawdles in the digestive tract. In fact, the insoluble fiber in some complex carbs, such as that in vegetables and whole grains, tends to block the absorption of other calories. "With a very high-fiber diet, say 60 grams a day, you might lose as much as 20 percent of the calories you consume," says Wanda Howell, Ph.D., a professor of nutritional sciences at the University of Arizona.
So a useful measure of calories is difficult. A lab technician might find that a piece of rock candy and a piece of broccoli have the same number of calories. But in action, the broccoli's fiber ensures that the vegetable contributes less energy. A study in the Journal of Nutrition found that a high-fiber diet leaves roughly twice as many calories undigested as a low-fiber diet does. And fewer calories means less flab.
We've been over this above. This information is calculated and applied to the calories listed on the label, including expected losses to urine, feces, and respiration. Fiber will slow the release of calories to the body, but will not reduce the total calories pulled from the food before digestion is complete.

Myth #4: Exercise Burns Most of Our Calories 
Not even close
Even the most fanatical fitness nuts burn no more than 30 percent of their daily calories at the gym. Most of your calories burn at a constant simmer, fueling the automated processes that keep you alive—that is, your basal metabolism, says Warren Willey, D.O., author of Better Than Steroids. If you want to burn fuel, hit the gas in your everyday activities.
"Some 60 to 70 percent of our total caloric expenditure goes toward normal bodily functions," says Howell. This includes replacing old tissue, transporting oxygen, mending minor shaving wounds, and so on. For men, these processes require about 11 calories per pound of body weight a day, so a 200-pound man will incinerate 2,200 calories a day—even if he sat in front of the TV all day.
And then there are the calories you lose to N.E.A.T., or nonexercise activity thermo-genesis. N.E.A.T. consists of the countless daily motions you make outside the gym—the calories you burn while making breakfast, playing Nerf football in the office, or chasing the bus. Brandon Alderman, Ph.D., director of the exercise psychophysiology lab at Rutgers University, says emerging evidence suggests that "a conscious effort to spend more time on your feet might net a greater calorie burn than 30 minutes of daily exercise."

Correct! Congratulations, Clint, this is actually correct!

Myth #5: Low-Calories Foods Help You Lose Weight 
Not alway
Processed low-calorie foods can be weak allies in the weight-loss war. Take sugar-free foods. Omitting sugar is perhaps the easiest way to cut calories. But food manufacturers generally replace those sugars with calorie-free sweeteners, such as sucralose or aspartame. And artificial sweeteners can backfire. One University of Texas study found that consuming as few as three diet sodas a week increases a person's risk of obesity by more than 40 percent. And in a 2008 Purdue study, rats that ate artificially sweetened yogurt took in more calories at subsequent meals, resulting in more flab. The theory is that the promise of sugar—without the caloric payoff—may actually lead to overeating.
"Too many people are counting calories instead of focusing on the content of food," says Alderman. "This just misses the boat."

Aspartame or diet soda *causing* obesity is ridiculous. The studies he mentions *associate* obesity with diet soda in the same way that obesity is associated with extra large clothes. We all know that wearing XL clothing won't make us fat, but wearing three XL t-shirts per week is also *associated* with increased risk of obesity! Stating that drinking three diet sodas per week is associated with obesity is the same type of statement.