Aidan:
Hello and welcome to the Ideal Nutrition podcast. My name is Aidan Muir, and I’m here with my co-host, Leah Higl. We’re going to be talking about the role of protein in fat loss and also how much you need. So we’re going to go through a few individual areas to start off with to give background context before we go deeper into the topic of how much you need to kind of optimise for this.
Leah:
Starting with satiety as our first kind of talking point. So we do know that protein is the most satiating macronutrient at least per calorie. So, technically, fat is more satiating per gram, but fat does have nine calories per gram as opposed to protein only having four. So again, per calorie, it is the most satiating of the macronutrients. So, when we think about tailoring our diet in a way that prioritises protein during fat loss, it’s probably going to be helpful in regards to hunger management.
So, if we’re less hungry, we’re more satiated, it is easier to maintain a deficit long-term. And honestly, for me, that’s one of the biggest selling points of the higher protein intake.
Aidan:
I’m going to reshare this here. I feel like I’ve shared this on the podcast, but in a previous job, I remember saying that fact, that it’s just a factual thing, protein is the most satiating thing, macro per calorie. And the boss at that job said, no, it’s not. I was like… it is, like, this is a fact. And then he like checked with like the head of dietetics and she also greeted him and it’s like, no, it’s not.
Leah:
Really?
Aidan:
Yeah. I was like, I don’t know what to do. Like, I’m just like, both my superiors are just wrong, and this is why I don’t like working for other people, I guess. But, anyway, moving on to another factor here. So, talking about how high protein intake could help with muscle retention, which will indirectly help with fat loss. And I think, to a degree, everyone knows this, but I want to go a layer deeper on here. So I think everyone listening to this is obviously aware that a calorie deficit is a key part of fat loss. Even if you know that, I think it’s still due diligence on my behalf in a way to go deeper on this.
So obviously, the reason why calorie deficit is relevant is because both muscle and fat are partly made up of calories. If we’re consuming fewer calories than we burn, it has to come from somewhere because calories are simply a unit of energy. Where does it come from? It comes from our body in the form of muscle, fat or glycogen.
If a calorie deficit is leading to weight loss over time, because it has to based on that definition with the exception of water weight, and then we have protein helping us retain more muscle, that therefore means a larger percentage has to come from either glycogen or fat, which therefore means very, very likely that higher protein retaining more muscle is going to lead to more fat loss over time because the deficit is kind of forcing there to be weight loss overall.
So, just a similar kind of like, even if a similar amount of total weight was lost, just more would be coming from fat. So high protein is indirectly helping more fat loss there too.
Leah:
There’s also the impact of the muscle retention itself on your resting metabolic rate. So, muscle is metabolically more active and it plays a role obviously in your resting metabolic rate. So we actually just burn calories sustaining that muscle. A simplified version of this is that more muscle means a higher metabolic rate, if we’re thinking body composition overall, but arguably this kind of overstates its importance a little bit.
So talking numbers, at rest, one kilo of lean mass is burning around 12 calories per day, as opposed to fat mass, which burns around four calories per day. So just based on those numbers, you can kind of feel like there is like a bit of a discrepancy in how much energy is required to sustain fat versus muscle. But when we put it into context of an actual human being, it sounds a little less impressive.
So, even if you had a really huge change in your body composition, like you lost 10 kilos of body fat and put on 10 kilos of lean mass. If we did the actual math on it, it probably wouldn’t change your resting metabolic rate that much. But if we extend it further to factor in how many calories you burn whilst you’re active or exercising, if you have a higher amount of muscle mass, you’re probably burning a more significant amount of calories.
So at rest, doesn’t make that big of a difference. It does make some though. But then once you factor in activity, the discrepancy in energy expenditure is probably more exaggerated.
Aidan:
The thermic effect of food is another similar one to that, where it’s a small but additive thing as well, where basically the thermic effect of food is the amount of energy your body uses, digesting, absorbing and metabolising nutrients. Protein has the highest thermic effect of food out of all of the macros.
When you consume protein, about 20 to 30 % of the calories are burned during digestion. So if you have a hundred calories from protein, about 20 to 30 kind of go missing in a way, as in your energy expenditure increases by that amount. With carbs, I say it’s around five to 10%. Obviously, it scales a bit based on fibre, because that’s a bit indigestible. It also requires more energy as well. And then fats, pretty low, like zero to 3%. That’s not huge. Let’s use one example to give a bit of context.
Say you reduce your carbohydrate intake by about 50 grams and you increase your protein intake by 50 grams. So your calories are stable. You’re just having a larger percentage coming from protein. This adds an extra 30 to 50 calories per day to total daily energy expenditure. similar to that resting metabolic rate thing where it’s like in practice, this isn’t huge, but it is still like a difference that is added onto this too.
Leah:
So bit of a subjective one next that is a little bit more vague, a little bit more broad, but by having a higher protein intake, it might actually inadvertently limit our food choices, which in the pursuit of fat loss and maintaining a calorie deficit may be beneficial in certain contexts.
So, if we’re thinking of your day-to-day life, things like getting takeout or having things on the run, like we’re probably going to be more mindful of what we’re choosing if we’re aiming for a higher protein intake, because those things tend to be higher in the fats and the carbs. So, we’re not getting as much protein per hundred calories in those foods.
So, we will likely rely a little less on takeout and less on these more energy dense, low protein options, which is going to potentially just, indirectly, help you maintain the deficit just because you are avoiding/ minimising these foods that are lower protein. But also again, from like the satiety perspective, super helpful.
Aidan:
On that topic, I remember my first year as a dietitian, I used to like, instead of doing the current plans like the way I do now, I used to have a different form of system. But one thing I’d have people try to do if they kind of were interested in doing this or agreeable to it or anything like that, would be to aim for at least five serves or six serves of vegetables per day.
I’d like to do five for women, six for men. And with like the takeaway concept, when you break down to what that looks like, it’s almost impossible to have takeaway twice a day and tick this box. You’d have to go so far out of your way to kind of make it work. And similarly, it just kind of forces, in a way, to make home-cooked meals to a degree.
Leah:
If you’re setting like a higher protein intake plus aiming for a certain amount of fruit or veg, it’s like naturally going to displace those other foods.
Aidan:
Yeah, a hundred per cent. Now, we’re going to go a little bit more nuanced with how much you need. And the reason why this is nuanced is because you literally don’t need protein to lose fat. Like if you quite literally ate no protein, but ate in a decent-sized calorie deficit, you would still be losing fat. It’s rare, but every now and then, it’s possible that in the pursuit of consuming a high protein intake, you could push yourself outside of a deficit.
Like you could consume too many calories as part of that pursuit. Obviously you can avoid that with some of the things we speak about a bit like protein efficiency. So like, choosing lower carb, lower fat protein sources, but it’s still relevant, particularly not super focused on trying to optimise muscle retention or anything like that. So, you don’t need protein technically. Everything we’ve spoken about is kind of a bit of insight as to why we think it’d be a good idea to aim for a decent protein intake.
But everything from here with the knowledge that you don’t technically need from that is more just like individual recommendations from a bit of a practical perspective.
Leah:
So how much do we actually recommend for protein intake when you are in a fat loss phase? A very simplified version of this is that we think most people should aim for at least 1.4 grams of protein per kilo of body weight per day.
In the context of someone who is a hundred kilos, this would be at least 140 grams of protein daily. So, it’s like not super high, but it’s not super low either. And the logic behind that is in relation to a combination of everything we’ve just spoken about. So, we’ve got the satiety, the muscle retention, the thermic effect of food, all of that. I often don’t set an upper limit with my fat loss clients from a protein point of view, I think it’s more something that each individual is going to be different based on their goals and based on what works for them.
I consider quite a large range to be acceptable, but having over that level of protein intake is often a good rule of thumb. If we were going to go the more advanced route, we could base things off of fat free mass instead of body weight alone because that is going to change your protein requirements in regards to your body composition overall. So, fat mass versus muscle mass. So, we could look at a range like 2.3 to 3.1 grams of protein per kilo of fat free mass, lean mass in the body. So, you would essentially estimate your body fat percentage or get a DEXA scan.
And then when you know roughly what your fat free mass is, you can then use that formula to figure out the protein intake range that you want to aim for. It’s a little more complicated than that and we could dive in deeper, but I think that’s again, a general rule of thumb if you wanted to use that slightly more advanced option. But the range overall is pretty big.
It doesn’t need to be something that’s like perfect. There’s no like perfect number to aim for. It’s going to be a bit of a case-by-case basis. And you might end up on the top end of the range. You might be on the lower end of the range. It’s all got all going to be about preference, logistics and goals.
Aidan:
Yeah. I like that last one in that I think it’s the most accurate way and it seems kind of complex to explain, but it is also really simple and, like, not being a perfectionist, like I own a DEXA scanner. So, I always encourage people to do that, but you could just roughly figure this out by Googling what your different body fat percentages look like on Google.
If something looks like, as an example, 20 % body fat, means 80 % of your total mass is lean mass or fat free mass. But, you can actually just figure it out through stuff like that. And because the range is so big, like an estimate is fine. Like, just put yourself somewhere in the range. If you’re cautious, you could go towards the top end if you really want to.
Summarising all of this, I would agree that like greater than 1.4 grams per kilogram of body weight protein per day is a recommendation I would give to the vast majority of people looking to lose body fat. There are exceptions, but I think it would make it easier in most cases.
This has been episode 210 of the Ideal Nutrition Podcast. As always, if you have not already, if you could please leave a rating and review, that would be massively appreciated.