Last week, I wrote about calories: what they are and how to figure out how many you need. I’m not sure how many of you thought about your own calorie needs over this past week. Were you curious? Did you do even a rough, mental calculation? Or is it something that isn’t of much interest to you? There are no right or wrong answers here, by the way.
Most of us have learned somewhere along the way that to lose one pound, you need a deficit of 3500 calories. You need to slash 3500 calories from your diet, burn off 3500 calories through exercise, or do a combination of both. We’ve also learned that weight change is a matter of calories in versus calories out. To lose weight, you must take in fewer calories; to gain weight, you need to consume more. But nutrition and health experts have recently questioned this dogmatic thinking. An expert panel, convened by the American Society of Nutrition and the International Life Sciences Institute, decided to take a long, hard look at what we believe to be true about calories.
Take the “3500 calories = 1 pound” rule. This equation assumes that you would lose weight linearly over time. What it doesn’t take into account is that the rate of weight loss changes, primarily because as you lose body weight, your metabolic rate slows down. To figure out your “real” rate of weight loss, researchers have developed a weight-loss predictor calculator that you can access here.
If a deficit of 3500 calories truly leads to a one-pound weight loss, then theoretically, a person would be expected to lose 52 pounds per year. In reality, we know this doesn’t happen, at least for most people. What’s probably more realistic and likely is that cutting calories by 500 per day (what’s generally recommended) may result in about a 25-pound weight loss over a year.
Another conundrum is the somewhat black-and-white thinking about the calories that we get from carbohydrate (4 per gram), protein (4 per gram), and fat (9 per gram). These calories are determined by population studies; individuals may obtain different amounts of calories from foods. The actual amount of calories that you derive from eating, say, a bowl of oatmeal depends on a number of factors, including how well you chew your food, your gut microflora (bacteria), how that oatmeal is prepared, and other foods that you eat along with it.
And yet another conundrum deals with exercise. Again, the age-old belief is that once you start exercising, the pounds are going to melt off. While some people may see this happen, other people are left scratching their heads; the scale hasn’t budged. The expert panel concluded that the body’s response to an increase in physical activity is often to compensate with additional food intake. So, if you start a walking program or head off to the gym, your body knows that you’re burning off energy (calories) and will try and make up for that by prompting you to eat more.
Much of the confusion around calories is perpetuated by health experts. Many doctors and dietitians will argue that “a calorie is a calorie.” Take in too many, you’ll gain weight. Cut back, you’ll lose weight. Of course, everyone’s metabolism is different, so that’s one factor that determines how quickly you lose weight. We also know that, in general, men tend to lose weight more quickly than women, for example. And older folks tend to have slower metabolisms than younger people.
Some people like to count calories. It provides a sense of control and it helps people track their food. Others will shy away from this approach. Have you ever counted calories? Did it work and, if so, for how long?
Does calorie source really make a difference?
A study published in The Journal of the American Medical Association showed that counting any type of nutrient (carbs, protein, fat) may not impact weight loss. In this study, 25 men and women were divided into three groups, each consuming more than 900 extra calories per day. Each group consumed a different amount of protein. All three groups gained weight, but the group consuming the least amount of protein gained the least amount of weight. But everyone gained fat at roughly the same rate. The conclusions: Calories are what matter as far as weight gain goes, not so much the type of calories.
But a study published in The New England Journal of Medicine in 2010 begs to differ. More than 120,000 men and women were followed in four-year intervals over anywhere from 12 to 20 years. On average, weight gain was 3 pounds during a four-year period. But those who ate more fruits, vegetables, whole grains, yogurt, and nuts gained less weight than those eating more refined carbs, like French fries, potato chips, and sugar-sweetened drinks. The lead author of the study argued that counting calories isn’t enough (if you’re trying to lose weight). You need to look at where those calories are coming from, too.
What’s the bottom line?
Calories do matter, but most people don’t know how many they should be taking in, and they also don’t know how much they’re actually consuming. Most people grossly underestimate their calorie intake, likely because they think they eat less than they really do. Being more aware of portion sizes can help with controlling calories, and reading labels and using food databases or smartphone apps can make you more “calorie conscious.” Calorie information is now available at fast-food and chain restaurants, so even if you decide not to avoid those 770 calories in Shake Shack’s Double ShackBurger, you at least know that the information is out there.