How The Physiology of Fat Loss Works:
Losing fat is much simpler than you’ve been led to believe.
The first, and most fundamental, of these mechanics is energy balance.
This refers to the relationship between the energy you give your body through eating food and the energy it expends through cellular and physical activity. It’s often measured in kilocalories (kcal).
The absolute immutable truth about meaningful weight loss…as demonstrated by thousands of controlled weight loss trials conducted over the last 100 years…is this: you must burn more energy than you consume.
You’ve probably heard this before but if you’re shaking your head in disappointment, allow me to explain.
When you eat food, you provide your body with a relatively large amount of energy in a short period of time. It burns a portion of this energy and stores a portion as body fat for later use.
The scientific term for this period of nutrient absorption and processing is “postprandial. Post means “after” and prandial means “having to do with a meal.” While in this postparandial or “fed” state, no fat burning occurs–the body is in “fat storage mode.”
The reason for this is simple: why should the body burn fat for energy when you’ve just provided it with all it needs plus quite a bit more?
Eventually your body finishes processing and absorbing the food, which can take several hours, and enters what scientists call the “postabsorptive” state.
The energy provided by food is now gone but the show must go on. What can your body do to meet its energy demands?
That’s right–it can burn body fat. Your body must now shift to “fat burning mode” to survive while it waits for its next meal.
Every day your body moves in and out of postprandial and postabsorptive states, storing and burning fat.
Here’s a simple graph that shows this visually:
The light portions show what happens when you eat food: insulin levels rise to help process the nutrients and fat burning shuts down.
The dark portions show what happens when your body runs out of energy from food: insulin levels drop, which tells the body it’s running out of energy and needs to start burning fat.
Now, what happens if these light and dark portions more or less balance out every day? You got it–you body fat levels stay the same. Your body is burning more or less as much fat as it’s storing.
What happens if the light portions outweigh the dark? Yup, you’ve stored more fat than you’ve burned and thus your total fat mass rises.
And what happens if the dark portions are collectively greater than the light? You’ve burned more fat than you’ve stored, which means your total fat mass decreases.
This is why meaningful fat loss requires that you burn more energy than you eat.
It doesn’t matter how many “unclean” foods you eat or when you eat them or anything else. Your metabolism runs on the first law of thermodynamics, which means fat (energy) stores can’t be increased without you providing a surplus of energy and can’t be decreased without you restricting energy intake, creating a deficit.
When talking pure weight loss, a calorie is a calorie. Your body only burns so much energy and if you feed it less than it needs, it has no choice but to continue tapping into fat stores to stay alive.
The goal isn’t to lose weight, though. It’s to lose fat and not muscle. And when that’s the goal, a calorie is not a calorie.
Certain types of calories are more important than others.
I’ve written about this extensively in my books and elsewhere, but here’s the long story short:
When you’re restricting your calories to lose fat, you must ensure you’re eating enough protein.
Research shows that when restricting calories, a high-protein diet is more effective at reducing body fat, helps preserve muscle, and increases satiety.
How much protein should you be eating, exactly?
Well, the government recommends 0.8 grams per kilogram of body weight, but research shows that double and even triple that amount isn’t enough to preserve lean mass while dieting.
Instead, I prefer to follow the advice of scientists at AUT University, who concluded…
“Protein needs for energy-restricted resistance-trained athletes are likely 2.3-3.1g/kg of FFM [1 – 1.4 grams per pound of fat free mass] scaled upwards with severity of caloric restriction and leanness.”
To keep it simple, my general recommendation is eating 1 to 1.2 grams of protein per pound of body weight when restricting calories for fat loss.
If you have quite a bit of fat to lose (if you’re a man with 20%+ body fat or if you’re a woman with 30%+), you can reduce intake to 0.8 grams per pound of body weight and you’ll be fine.
So, now that you understand how the body builds muscle and stores and burns fat, let’s see what it takes to do both at the same time.