21/01/2026
Given the increased focus on dieting at this time of year, this felt like a good time for a reminder about why calorie (or kilojoule) counting isn’t as helpful as we’re often led to believe.
Calorie counting is often one of the first things we think of when it comes to weight loss, but weight regulation is complex, and calories are only one small part of the picture.
Your body’s decision to store fat or use energy is influenced by many factors including:
• thyroid function
• hormones (thyroid, stress, s*x hormones, insulin)
• gut microbiota
• sleep quality
• stress
Another important and often overlooked factor is that your body absorbs calories differently depending on the type of food, so we can’t really compare calories across foods in the way many apps suggest.
Fats are relatively easy for the body to break down, so around 97% of calories are absorbed from fat.
Carbohydrates are absorbed at around 90–95%, depending on the type (more calories are absorbed from simple sugars, compared with complex carbohydrates).
And when it comes to protein, we absorb only around 70% of the calories.
⚠️ Processing also influences calorie absorption, and because processing breaks down food structures and makes nutrients easier to absorb, we absorb more calories from ultra-processed foods.
Minimally-processed foods are more intact and take more energy to digest, so we often absorb fewer calories overall from these types of foods.
👉🏼 Fibre helps slow digestion and reduce calorie absorption, as intact fibre isn’t absorbed in the small intestine - instead this travels further down to the large intestine to be fermented by gut microbes.
This is just one reason why rigorous calorie counting can be inaccurate, frustrating, and unhelpful for many people.
The number on a package (or in an app) is likely not the same as what your body actually absorbs, and there’s a lot more going on behind the scenes in your body that a tracker can’t account for.
