I have a question for you: Is a calorie just a calorie?
Total calories consumed is the most fundamental variable to be considered when striving to lose weight. Quite simply, you can’t lose weight unless you consume less calories than you burn. However, does it really matter where those calories come from? If you indulge in your favorite foods (ice cream & cookies, for example), but stay under your maintenance level in calories, will you still see weight loss?
The answer to this question is both yes and no. Mark Haub, a nutrition professor at Kansas State University, experimented on himself with what he called the “Twinkie diet.” Every three hours he ate a Twinkie (or other Hostess/Little Debbie snack), consumed one protein shake a day, and occasionally vegetables—all totaling no more than 1,800cal per day. (Although the bulk of his diet came from the junk food). The result: Haub lost 27 pounds in 8 weeks.
Strictly in terms of weight loss, all calories seem to be created equal.
However, there is more to this equation than weight loss alone. If all we’re after is the number on the scale to decrease, then this approach may work. On the other hand, if changes in body composition (ratio of lean body mass to body fat) is the goal, then the source of the calories begins to matter. Consuming more nutrient-dense foods can provide a number of benefits. For example, a diet higher in protein will help you preserve muscle tissue while losing body fat.1 As a result, you can become stronger, with a higher metabolism and less body fat, compared to losing both body fat and muscle tissue on a low-protein diet.
What are some other benefits to consuming nutrient-dense foods in place of junk foods to fulfill your daily caloric requirements?
Nutrient-dense foods contain fiber and other stomach-filling nutrients. Not to mention, vegetables tend to have very low caloric content, which means you can consume a much larger quantity of vegetables compared to higher-calorie junk foods. A twinkie contains 150cal; in order to eat this many calories in spinach you would have to eat 1.5lbs, or about 12 cups. Additionally, the spinach would also contain about 15g of protein and fiber, compared to only 1g of protein (and zero fiber) in a twinkie. Choosing low-calorie, nutrient-dense foods will help you feel more satisfied and stay full longer.2
Due to the generally lower calorie content of wholesome foods, you will be able to increase the quantity of the food in your diet. 500 calories of peanut butter (although a pretty nutrient-dense, wholesome food) is about four and a half tablespoons—only enough to fill a small bowl. 500 calories of salad with mixed veggies and lean protein can be enough food to fill a large serving bowl. As one enters a caloric deficit, the ability to increase food quantity can be an important factor in adherence to the diet.
More energy (less crashes)
Due to the higher fiber and protein intake, nutrient-dense foods will give you longer-lasting energy throughout the day. Generally, foods rated higher on the glycemic index—the scale that measures how strongly a food will increase blood sugar levels—will absorb more quickly often leaving you fatigued and sleepy shortly after consumption (think food coma). Dietary fats and protein can slow the digestion of other nutrients present in the stomach, leading to a slower increase in blood sugar, a reduced crash afterwards, and a more sustained source of energy during the digestion process.
A certain percentage of our daily energy expenditure is allocated to the thermic effect of food (TEF)—the amount of energy it takes to digest, metabolize, and absorb the nutrients we consume. Protein has the highest TEF, compared to both fats and carbohydrates.3,4
As high as twenty-five percent of protein calories are used just to digest the food, meaning 100 calories of protein would actually end up being closer to 75 calories by the time it is fully digested. Fats and carbohydrates, on the other hand, have a TEF closer to two (fats) and six (carbohydrates) percent. This means 100 calories of fats or carbohydrates would come out to between 94-98 calories after digestion, respectively.
The notion that a “calorie is just a calorie” can be beneficial when it comes to learning how to incorporate your favorite foods back into your diet (on special occasions). However, consuming nutrient-dense, wholesome foods such as: fruit, vegetables, lean protein, and whole grains will allow you to make positive changes to your body composition and other health markers. These foods should undoubtedly make up the majority of your day-to-day diet.