Is Your Calorie Counter Lying to You?
Today's episode was suggested by listener James who called into the nutrition diva listener line with this question. Hey, Monica this ah, James. I was wondering if you could devote an episode. On calories, and what they are how they're measured and how we process them, even though they're just a measurement of food and not actual food and what a bomb Colorado or is. And all the problems with counting calories. So that would be awesome love to hear that. But cast. Thanks. Thanks for this. Great topic. James? So let's start with what a calorie is. And how we know. How many calories food contains a calorie is a unit of measure like an inch or a kilogram only instead of measuring length or wait a calorie measures energy, technically a calorie is the amount of energy it takes to raise one gram of water by one degree celsius. Calories can be measured using something called a bomb calorie meter, isn't that a fun name? You might even have built a crude version of a bomb calorie meter in sixth grade science class in broad strokes. You submerge a chamber in a bucket of water, and you put a thermometer in the water, and then inside that submerged chamber, you set something on fire the heat generated by the combustion raises the temperature of the water in the bucket, and you can measure that with the thermometer, and then you can calculate the amount of energy or calories were in the thing that you set on fire. So we used to use bomb calorimeters to calculate. How many calories given food contains these days? However, it's much more common to estimate the number of calories based on how much protein fat and carbohydrate food contains and those amounts can be determined through chemical analysis. Now when we're using the word calorie in relation to food, by the way, we are actually referring to kill calories. Sometimes you'll see calories abbreviated as k Cal. And that's what that refers to when we say that food contains sixty calories. It really contains sixty thousand calories, but although zeros would be a pain to deal with. So we just LOP them off. And believe me, this drives physicists and chemists. Absolutely nuts. But why do we need to know? How many calories food contains while when we digest food? We don't literally set it on fire in our stomachs, but our bodies do release it's stored heat or energy. And then we either use that energy to power our biological processes. Or if we've taken in more energy than we need. We store it for future use if we habitually taken more energy than we use we gain weight. So we use calories as a guide. Line to determine how much food energy a person needs. We need enough to fuel growth and maintenance, but not so much that we start storing a lot of fat. There are calculators. I'm sure you've seen them that can estimate your daily calorie needs taking into account, your age, sex, height inactivity level, and then there are databases and labels to tell you. How many calories are in various foods? However as James implies in his question. There are a few problems with this system. First of all those calorie needs estimates can be way off you can plug your details into an online calculator and be told that you use eighteen hundred forty seven calories per day. But look you need to take that number with a truck load of salt energy expenditure varies hugely from person to person. Even if you and I are the exact same height weight age and sex, and we do the exact same workout. You could burn four hundred calories more or less than I do every day and energy needs can also be affected by our diets genetics body. Position hormones drugs and a million other factors and moving targets and just to make the whole situation just a little bit more ridiculous. Those readouts on your treadmill peleton fit watch or diet tracker that tell you how many calories you burn doing various activities are only slightly more accurate than asking the magic eight ball. But wait. There's more calorie counts for foods are also not as reliable as you think those numbers that are listed in your calorie counting app represent average values for foods. So even if you are measuring or weighing your food with great precision. Well, this apple may be a little bit sweeter than average that banana might be a little less ripe. This not might have a little bit more fat even for packaged, and processed foods the calorie count that's shown on the nutrition facts label is just an average of variation of. Plus or minus ten percent of that value would not be at all surprising. Secondly, those calorie counts are estimated using formulas that may or may not be one hundred percent reliable. It was recently discovered, for example, that the standard formulas that were in use for most of the last hundred years where overestimating the amount of energy that we humans are able to liberate from nuts. More modern method suggests that almonds for example, provide about twenty percent less energy or fewer calories than we previously thought. And finally, our bodies are not bomb calorimeters like a campfire that might go out and leave a few unburned chunks of wood our bodies don't extract all the energy from our food, some unknown and variable amount of that energy will pass through us unabsorbed.