E210 – The Role of Protein in Fat Loss (And How Much You Need)

Topic 1: How Protein Helps with Fat Loss

We’re breaking this down into key areas to give context around why protein plays such a significant role in fat loss:

Satiety

Protein is the most satiating macronutrient per calorie
Technically, fat is more satiating per gram. But it has 9 calories per gram, and protein only has 4.
Meals and snacks higher in protein tend to reduce hunger more than other options. And if a larger percentage of total calories comes from protein, it can often inadvertently reduce calorie intake, or just make it easier to stay in a deficit.

Muscle Retention & Increased Fat Loss

I assume everyone listening to this is aware that a calorie deficit is a key part of fat loss.
Even if you know this, I think it’s due diligence on my behalf to add this context before talking about protein’s role here.
The reason why a calorie deficit is relevant is because both muscle and fat are partly made up of calories.
If we consume fewer calories than we burn, they have to come from somewhere, since they are simply a unit of energy.
They have to come from our body in the form of muscle, fat or glycogen.
This is why a calorie deficit has to lead to weight loss over time, with the exception of things like water weight.
We know that protein helps with muscle retention or growth.
In a calorie deficit, your body gets energy from muscle, fat, or glycogen. Eating enough protein helps preserve muscle, so more of the weight lost comes from fat instead.
So even if a similar amount of total weight were to be lost, more will be coming from fat.

Muscle Retention & Resting Metabolic Rate

Muscle is metabolically active and plays a role in resting metabolic rate.
A simplified version is that more muscle means a higher metabolic rate, but arguably that overstates it.
Another oversimplified formula I like is that 1kg of lean mass = ~12 calories burned per day and 1kg fat mass = ~4 calories burned.
That sounds impressive until you factor in that even with a very impressive difference in body composition changes within an individual, it doesn’t actually add up to much practical difference.
You could extend this further though by factoring in that the body composition difference can add up to more energy expenditure elsewhere, such as during training.
So that makes it a bit more of a variable that is relevant.

Thermic Effect of Food (TEF)

The thermic effect of food is the energy your body uses to digest, absorb, and metabolise nutrients. Protein has the highest TEF of all macronutrients.
For context:
- Protein: ~20–30% of its calories are burned during digestion
- Carbohydrates: ~5–10%of
- Fat: ~0–3%
This means that if you eat 100 calories from protein, 20-30 calories are burned just to process it.
It’s not huge but it’s another variable. Let’s say somebody adds 50g protein and reduces 50g carbs, so calories are stable. That adds an extra 30-50 calories to total energy expenditure for the day.

Limiting Food Choices (Indirectly Helpful)

This is a pretty subjective one.
But sometimes the pursuit of higher protein intake as a percentage of total calories can limit your food choices in a way that indirectly reduces calories.
For example, if getting takeaway or eating out, it might push you towards options that are lower in fat and higher in protein, which could reduce total calorie intake.
It also might push things towards more prep at home too just due to the logistics of getting a decently high protein intake.
This is case by case, but I still think it’s a factor.

Topic 2: Nuance Around How Much Protein You Need

The nuance here is that you literally don’t need protein to lose fat.
If you ate no protein, but still ate in a decent sized calorie deficit, you would still lose fat.
It’s rare, but sometimes the pursuit of a high protein intake can push people out of a deficit and actually reduce fat loss. This can be avoided with more of a focus on protein efficiency. But it’s still relevant, particularly if somebody isn’t that phased about optimising muscle retention.
Outside of that, it’s hard to give specific recommendations as a broad rule since it’s not even necessarily needed for this purpose. So everything here is just our own individual recommendations from a practical perspective.

Topic 3: How Much We Typically Recommend

My very simplified version is that I think most people should aim for >1.4g/kg/day (e.g. 140g or higher for a 100kg individual).
The logic behind this is in relation to a combination of everything we’ve spoken about. This will help with satiety, muscle retention and the thermic effect of food.
I don’t set an upper limit because there’s a huge range that’s okay and it’s rare, but not unheard of, to see somebody go above what I’d consider acceptable.
if I were to go more advanced my range changes to 2.3-3.1g/kg of fat free mass. So you’d estimate your body fat percentage or get a DEXA and then when you know your fat free mass, you use that formula. It’s more complicated to communicate, but pretty easy to actually do. This optimises muscle retention.
The range is pretty big, so you don’t need to be perfect either, since if you are cautious you can just go towards the top end.

Summary

Protein plays a powerful role in fat loss by increasing satiety, preserving muscle mass, boosting metabolism, and raising the thermic effect of food. While not essential for losing fat, a higher protein intake can make the process easier and more effective.