The science behind calorie quality, revealing how different foods affect metabolism, satiety, and overall health.
“Not all calories are equal because the body responds differently to calories from various food sources,” says Dr. David Ludwig, an American nutrition professor at the Harvard School of Public Health.
He emphasises that refined carbohydrates like such as white bread, pizza dough, pasta and pastries raise insulin levels, prompting fat storage and leading to increased hunger, whereas high-fat foods like nuts, avocados, and fish promote weight loss and reduce disease risks.
Understanding the nuances can be a game-changer for those seeking sustainable health and wellness.
The Thermic Effect of Food: Yes, Burning Calories While Eating is possible
One critical factor often overlooked is the thermic effect of food, which refers to the energy expended during digestion and absorption. So the great news (for all), is that we can burn calories while we are eating.
Not all foods have the same effect, for instance, protein has a Thermic Effect or TEF of approximately 25%, meaning that 25% of the calories from protein are used during digestion. But other foods like fats (avocado, hummus etc.) have a TEF of about 2%. This implies that 100 calories from protein can result in a net gain of 75 calories, whereas 100 calories from fat can result in 98 net calories.
Different foods affect calorie burn differently, protein burns more calories during digestion than fats, meaning someone can absorb fewer calories from protein than from fat.
Satiety and Hormonal Responses: The Fullness Factor
Beyond digestion, the type of food consumed influences satiety, the feeling of fullness and hormonal responses.
Protein-rich foods tend to increase levels of hormones, which promote satiety, while reducing levels of the hunger hormone ghrelin. This is why many people recommend starting your day with some protein so that your satiety during the days stays in track. Here are some high protein snack ideas.
Nutrient Density: More Than Just Calories
Calories measure energy, but they don’t account for the nutritional value of foods. Nutrient-dense foods, such as vegetables, fruits, whole grains, and lean proteins, provide essential vitamins, minerals, and fiber, contributing to overall health.
In contrast, calorie-dense but nutrient-poor foods often high in added sugars and unhealthy fats can lead to weight gain and other health issues despite providing the same or even fewer calories.
Some nutrient-dense foods include…
- Berries
- Sweet potatoes
- Kale
- Spinach
- Avocado
- Broccoli
The Role of Food Processing: Impact on Caloric Availability
The degree of food processing affects how many calories the body absorbs. Highly processed foods are often easier to digest, leading to more calories being absorbed. Conversely, whole foods require more energy to break down, resulting in fewer net calories. For example, studies have shown that individuals absorb fewer calories from whole almonds compared to processed almond butter
Another example could be with corn. When people eat whole-kernel corn, a significant portion of the kernels passes through the digestive system undigested, meaning fewer calories are absorbed. However, when corn is ground into cornmeal and used to make products like cornbread or tortillas, the body digests it more efficiently, leading to greater caloric absorption.
Glycemic Index and Blood Sugar Levels: Energy Peaks and Valleys
Foods with a high glycemic index (GI) cause rapid spikes in blood sugar levels, leading to quick energy bursts followed by crashes. These fluctuations can increase hunger and lead to overeating. Low-GI foods, such as legumes and whole grains, provide a slower, more sustained release of energy, promoting satiety and reducing overall calorie intake .
Some low GI foods include.
- Apple
- Banana
- Eggplant
- Lemons
- Lettuce
- Carrots
- Peanuts
Practical Implications: Making Informed Choices
Understanding that not all calories are equal empowers individuals to make more informed dietary choices. Prioritising whole, unprocessed foods rich in protein and fiber can enhance satiety, boost metabolism, and improve overall health. While calorie counting can be a useful tool, focusing solely on numbers without considering food quality may not lead to the desired weight loss let alone health outcomes in the long term.
