Not All Calories Are Equal – A Dietitian Explains How the Kinds of Foods You Eat Matter to Your Body

A calorie is a calorie is a calorie, at least from a thermodynamic point of view. It is defined as the amount of energy required to raise the temperature of 1 kilogram of water by 1 degree. Celsius (2.2 pounds per 1.8 degrees Fahrenheit).

But when it comes to your body’s health and energy balance, not all calories are created equal.

For example, some studies have reported that diets that are high in protein, low carb or a combination of the two produce greater weight loss than diets with other levels of fat, protein, and carbohydrates.

If all food calories were the same, you wouldn’t expect to see differences in weight loss between people who eat the same number of calories spread over different types of food.

dieticians like me know that there are many factors that influence what a calorie means to your body. Here’s what we know about calories and nutrition so far.

Really available energy for your body

In the late 19th century, chemist WO Atwater and his colleagues devised a system for calculating how much energy, that is, how many calories, are contained in various foods. Basically, he burned food samples and recorded how much energy they released as heat.

However, not all of the food energy that can be burned in the laboratory is actually available to your body. what scientists call metabolizable energy It is the difference between the total energy of the food you eat and the energy that leaves your body, undigested, in your stool and urine. For each of the three macronutrients (protein, carbohydrates, and fat), Atwater devised a percentage of the calories they contained that would actually be metabolizable.

According to the Atwater system, one gram of each macronutrient is estimated to provide a certain number of calories. The US Department of Agriculture still uses these calculations today to arrive at a official number of calories for each food.

how much energy do you use

What you eat can affect what scientists call the health of your body. Waste of energy. That’s the amount of energy it takes to keep you alive (energy you use to breathe, digest, keep blood flowing, etc.), along with the energy you exert to move your body. you may have heard this called metabolism.

The quality of the diet can alter the body’s energy expenditure, which is also called thermic effect of food. For example, in one study, people who ate the same number of calories per day but were on a low-carbohydrate or low-fat diet had differences in total energy expenditure about 300 calories per day. Those on very low-carb diets used the most energy, while those on low-fat diets used the least.

In another study, high-fat diets led to a reduction total energy expenditure than high-carbohydrate diets. Other researchers reported that although substituting carbohydrate for fat did not alter energy expenditure, people who increased their protein intake to 30%-35% of their diet used more energy.

In general, diets rich in carbohydrates, fat or both produce an increase of 4% to 8% in energy expenditure, while meals high in protein causes an increase of 11% to 14% above the resting metabolic rate. Protein has a greater thermic effect because it is more difficult for the body to break down. Although these variations are not huge, they could contribute to the obesity epidemic encouraging a subtle increase in average weight.

Quality of the calories you eat

Dieticians pay attention to a glycemic index of foods Y glycemic load – that is, how quickly and by how much your blood glucose levels will rise. An increase in blood glucose triggers the release of insulin, which in turn influences energy metabolism and the storage of excess energy as fat.

Foods like white rice, cakes, cookies, and chips have a high glycemic index/load. Green vegetables, raw bell peppers, mushrooms, and legumes have a low glycemic index/load. There is some evidence to suggest that foods lower on the glycemic index/load maybe best for keeping blood sugar levels regulated – regardless of the calories they contain.

Reward centers in the brain light up when people eat high glycemic index/load foods, highlighting the pleasant and addictive effect of foods such as sweets or white breads.

The fiber content of foods. is another thing to consider. Your body cannot digest fiber, which is found in plant foods like fruits, vegetables, whole grains, and beans, for energy. So high-fiber foods tend to have less metabolizable energy and can help you feel full on fewer calories.

Empty calories, those from foods with little or no nutritional value, are another factor to consider. Things like white sugar, soda, and many ultra-processed snack foods don’t provide much, if any, benefit in the form of protein, vitamins, or minerals along with their calories. the opposite would be nutrient rich foods that are high in nutrients or fiber, while still being relatively low in calories. Some examples are spinach, apples, and beans.

And don’t think of empty calories as neutral. Nutritionists consider them harmful calories because they can have a negative effect on health. The foods that contribute the most to weight gain They are French fries, potatoes, sugary drinks, and meats, both processed and unprocessed. On the other hand, foods that are inversely associated with weight gain are vegetables, whole grains, fruits, nuts, and yogurt.

More to your health than calories and weight

It is indisputable that for weight loss, the difference between the number of calories consumed and the number of calories exerted through exercise is the most important factor. But don’t be fooled. While weight does play a role in health and longevity, weight loss alone does not equal health.

Yes, some high-protein diets do seem to promote weight loss, at least in the short term. But epidemiologists know that in areas where people live the longest (about 100 years on average) eat a primarily plant-based diet, with little or no animal protein and little or moderate fat in the form of monounsaturated and polyunsaturated fats.

I often hear friends or clients say things like “those carbs are making me fat” or “I need to go on a low carb diet”. But these complaints drive dietitians like me crazy. Carbohydrates include foods like Coca-Cola and candy canes, but also apples and spinach. Reducing the consumption of simple carbohydrates such as soft drinks, bakery products with refined flour, pasta and sweets will definitely have a positive impact on health. But cutting out carbohydrates like vegetables and fruits will have the opposite effect.

A plant-based diet high in plant-based protein and carbohydrates mainly from vegetables, fruits, nuts and legumes is healthiest diet known to researchers for longevity and the prevention of chronic diseases such as heart disease, cancer, hypertension and many other conditions.

The modern Western diet suffers from a increase in the number of calories consumed with a competitor decreased quality of calories accomplished. And researchers now know that calories from different foods have different effects on satiety, insulin response, the process of converting carbohydrates into body fat, and metabolic energy expenditure.

When it comes to your health, count more on the quality of the calories you eat than on the calorie count.

Written by Terezie Tolar-Peterson, Associate Professor of Food Science, Nutrition and Health Promotion, Mississippi State University.

This article was first published in The conversation.