Allow me to introduce you to the simple energy balance equation:
Calories in = calories out, in this case, all is balanced and your weight stays the same.
Or more specifically...
Calories in = BMR (basal metabolic rate) + TEF (thermic efffect of food) + TEA (thermic effect of activity)
If calories in < calories out, you consume more calories than you use (a "calorie deficit"), you lose weight.
From a strictly biological perspective you can't get around it. You need to use more energy than what is coming in to lose that fat.
However, what this doesn't account for is; firstly, your health, and secondly, how the quality/composition/timing of the food you eat affectsyour ability to control your eating (calories in).
So why do quality, composition, and timing matter, but still don't change the fact that less energy has to come out than in to lose fat?
Because they all affect what's going on inside.
To start... your hormones, which firstly control your appetite - thus affect how easy it is to maintain this "calorie deficit".
Secondly, health issues (i.e. insulin resistance and other metabolic problems) are affected, which in turn affects your ability to absorb and correctly store food energy.
Most importantly... calories in vs. calories out completely ignores nutrient density. Not all calories are created equal.
In a study of over 120,000 healthy women and men over the course of 20 years, it was found that the consumption of processed foods higher in starches, refined grains, fats, and sugars can increase weight gain.
Another interesting study found that nutrient density alters your experience of hunger. Again, effecting the "calories in" side of the equation.
QUALITY MATTERS.
Finally, and most interestingly, your gut microbiome! Which affects both how you absorb and store energy and also the production of many vital hormones. I recommend following Dr. Tim Spector who frequently discusses this topic.
To summarise: Calories in < calories out = weight loss! But... the quality, composition, and timing (discussed less here) affect your ability to achieve this deficit.
Next week I will discuss how we can affect our BMR (metabolism), TEF (energy digesting food), and TEA (activity), to either lose more fat or eat more without gaining fat!