Being in a calorie deficit doesn't always = fat burning.

In fact, sometimes it can = fat storage.

Here's why...

We've been taught that if we consume more calories than our bodies need, then we store it as fat and if we consume too few calories, then we have to make up for that deficit by burning our fat stores for energy.

There's a big problem with this model...

It completely ignores the role of hormones.

Let's say you eat 1800kcal one day and so does your friend.

You eat foods that are rich in protein and fat, which means your insulin, glucagon and cortisol remain steady.

Your friend eats foods that are low calories (so that she can have more of them).

Low-calorie foods are high carb and lack fat, and because carbs digest into sugars, her blood sugars are up and down like crazy, meaning her body has had to produce a lot more insulin than yours to help normalise her blood sugar levels.

You both consumed 1800kcal, but she spent more time in fat storage mode because insulin is your fat storage hormone.

You spent more time in fat burning because when blood sugars are steady and insulin is low, the hormone glucagon can get to work by breaking down fat stores for you to use as energy.

There's another problem with the calorie model...

The theory is that when we're in a calorie deficit, we burn fat.

However, we also have muscle as a possible source of fuel.

Just because you're in a calorie deficit, doesn't necessarily mean you're making up the shortfall with body fat.

You may be breaking down muscle instead.

There's another problem...

Taking calories too low, or prolonged calorie restriction is a worrying situation for your body.

Your body thinks there's a famine and will start to reduce energy expenditure (burn fewer calories) to conserve energy and prevent starvation.

If you're someone who is already stressed, peri-menopausal, getting less than 7 hours sleep per night, has underactive thyroid or chronic fatigue, you're going to experience this starvation response or metabolic down regulation far sooner.

This is why calorie deficits don't always = fat-burning.

This is why you need to focus on nourishing your body instead of starving it.