According to the laws of thermodymanics, all calories are created equal (at least on paper), BUT (and this is a big but) the way our body breaks down carbohydrates, protein and fat, the three main sources of calories in our diet, and the effect they have on our bodies differ tremendously. How our bodies break down, burn and store each of these sources is what is most important. (I’m not touching on the fourth sources of calorie consumption, that of alcohol, because that is a whole different topic.) So let’s explore the question, “Are all calories created equal?”
Fats
In addition to being a potent and flavorful source of energy, fats slow digestion, deliver important fat-soluble vitamins to the body, and provide important building blocks for every one of our cells. All dietary fats provide about 9 calories per gram but, as you likely already know, some fats are better for our health than others. For example, polyunsaturated omega-3 fats, found in foods like wild salmon and flaxseed, have protective, anti-inflammatory properties, whereas artificial trans fats have been linked to increased inflammation, heart disease, and so much more!
Protein
Protein also keeps us feeling fuller for longer and is slowly digested, but its primary role in the body is to maintain and build new cells. Protein needs are greatest during childhood, adolescence and pregnancy, when the body is growing and adding new tissues. But we now also know that protein is very beneficial during weight correction phase. It contributes to satiety and offsets the amount of lean muscle that is burned for energy, in addition to fat, during a calorie deficit.
All proteins provide about 4 calories per gram but there are higher quality proteins, which may reduce appetite and optimize muscle repair and recovery (think: fish or eggs), and lower quality proteins (think: red meat) that are loaded with branched-chain amino acids, which have been linked to metabolic disease and insulin resistance. In this case, you get more nutritional bang for your buck if you consume 4 calories of high quality protein. FISH!
Carbohydrates
When it comes to differentiating calories, carbohydrates are by far the most complex (pardon the pun) mostly because our bodies use the different types of carbohydrates (such as fiber, starch and sugar) in very different ways.
Carbohydrates are used by the body as a quick source of energy. All carbohydrates (with the exception of fiber, which our body can’t digest) provide 4 calories per gram. But just as there are healthier fats and higher-quality proteins, there are varying degrees of carbohydrate quality.
Though not a source of calories, fiber is considered a high-quality carbohydrate since it slows digestion (thus making you feel fuller, longer) and can moderate the absorption of other nutrients, like sugar. For this reason, high-quality carbohydrates typically contain fiber and are minimally processed. These include fruits, vegetables, whole grains and legumes. Lower-quality carbohydrates almost always lack fiber and add little more than “empty calories” to our diets. (with the exception of dairy which contains natural sugars packaged with protein – like Greek Yogurt).
So you can see that a calorie from fat is not the same as a calorie from protein or carbohydrate. But let’s compare calories from two different types of sugar: glucose and fructose.
Starchy foods like rice, potatoes and pasta, are predominantly made up of glucose, a simple sugar that that can be burned for energy by every cell in our bodies. It’s stored in our liver and muscles for a quick source of energy during exercise or while we sleep. Unprocessed starchy foods, like brown rice, potatoes with the skin on and 100% whole-wheat or whole-spelt pasta, contain natural fiber as well as some vitamins and minerals. (Yellow Light or Slow Down Foods on my plan, but still healthy in correct portion!)
Unlike glucose, which can be burned for energy by all organs, fructose can really only be broken down in the liver. It’s also the sweetest tasting of the three simple sugars which makes it enjoyable on the taste buds. In nature, fructose is found in fruits bound tightly to indigestible fiber that, as we already know, reduces and slows its absorption. Unfortunately, the majority of fructose in the Standard American Diet (or SAD for short) isn’t from fruits at all, it’s from calorie-containing sweeteners added to sweetened beverages and the majority of processed foods—including breads, yogurts, condiments (ketchup, mayonnaise, dressings), milk substitutes (rice, almond, soy, non-dairy), most instant or frozen foods, and worst of all in my opinion are vitamin or energy waters and drinks . . . and in ridiculous amounts!
Here’s the main difference between these two sugars: While too many calories from glucose can lead to weight gain and accumulation of the less harmful subcutaneous fat, too many calories from fructose (found in calorie-containing sweeteners like sugar, honey, high fructose corn syrup etc…) can overwhelm the liver, contributing to nonalcoholic fatty liver disease, insulin resistance and more.
So as you can see, a calorie of carbohydrate is not the same as a calorie from fat or protein, nor are all carbohydrate calories created equal. As a general rule of thumb, I recommend consuming the majority of your calories from (good) minimally processed or (best) unprocessed whole foods since, ultimately, the quality of what we eat determines the quantity of calories we consume, which impacts not only our weight but also our overall health and wellness, and isn’t that what we are trying to accomplish by fueling our bodies!?
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