Chapters:
00:00 Intro
00:34 Prior studies
00:56 Our study
03:37 Protein leverage
05:47 Hard data
06:55 Conclusion
Transcript:
You’ve probably heard people say that protein is more satiating than carbs and fats. As a result, many people are advised to increase their protein intake beyond what’s required for muscle growth to help with fat loss. Because if protein helps make you full and reduces your appetite, that makes cutting easier, makes it easier to lose fat. However, while it is true that high protein diets are more satiating than low protein diets, it is not true that protein is inherently more satiating than carbs and fats. Let me explain.
The evidence for the idea that protein is inherently more satiating, that carbs and fats comes almost exclusively from studies on relatively low protein intakes, at least by bodybuilding standards, in people that don’t lift. So we are interested in if there are still benefits to increasing your protein intake beyond what’s required for muscle growth when you are in energy deficit will that still lead to greater appetite supression? So we did a study to find out.
We had a group of strength trained individuals perform a one week diet in a 20% energy deficit, once with 1.8g/kg per day as their protein intake, and once with 2.9g/kg per day as their protein intake. We chose these protein intakes because 1.8g/kg per day is roughly what I recommend as a general guideline for how much protein you need to maximize muscle growth and strength development. So we wanted to compare that protein intake, which is the maximum that the body will use for muscle growth and strength development, versus a much higher protein intake, in this case 2.9g/kg per day, which is over 50% higher. We chose a very high protein intake, but one that was still manageable and somewhat realistic to make sure that we had a big difference between the groups, so that if there was any difference in the satiating effect of the protein, it should be visible, but also to look at the protein intake that was still somewhat practical. And then we measured many measures of hunger, appetite and diet adherence. We found that on none of those measures were there are significant differences between the groups. Specifically we found no differences between the groups in fullness, desire to eat, cravings or hunger. Nor were there are differences in energy levels, mood, training enjoyment or training motivation.
We also looked into mini-experiments that we added to it if there were habituation effects, meaning if the response to a certain protein intake changed in either appetite hormones or appetite reaction. we found no evidence of any habituation, indicating that the long term effects would probably be very similar to what we observed in this study. In prior research there was actually a habituation effect of high protein diets, meaning that high protein intakes were more satiating at first, but then people habituated to that to basically desensitized to the high protein intake, and it was less satiating after a period on the diet. We did not find concrete evidence of this, but we also did not find increased satiety from higher protein intakes to begin with, beyond an already high protein intake that was sufficient to maximize muscle growth and strength development. This is in line with a previous meta analysis that I co-authored, where we found that the break off point for most individuals is about 1.6g/kg per day. After that point, there were no further increases in lean body mass in the literature with higher protein intakes. So it seems that protein augments muscle growth and strength development up to about 1.6g/kg per day. And if we add a safety mark up to that, which is called a triple sigma method in business research, to make sure that we are really catching all of the population, we get 1.8g/kg per day, or in freedom units- 0.82g per pound per day.
Now, if you’re familiar with the literature, you might be skeptical of our study findings because there are loads of studies that find that higher protein intakes are, in fact, more satiating than lower protein intakes. People report less hunger on high protein diets than they do on low protein diets. Why did our study find something else? It all comes down to the dosage. There’ve been many other studies in which higher protein intakes did not reduce hunger, just like we found in our study. Now, the difference between these studies and our study, and many of the other studies of low versus high protein diet, is the amount of protein. And this can be explained by a phenomenon known as protein leverage. Protein leverage theory states that we essentially have a protein stat in our bodies that makes us consume food up to the point at which we have consumed enough protein. So it’s a bit like we have a drive for sodium or water where we have some innate drive that makes us consume these things up to a certain point. Like, we like salty food, but only up to a certain point. And if we get dehydrated, we automatically get thirsty. So we have that with food in general, but it seems that we also have that with protein intake specifically. And there is research on the mechanisms of how this occurs.
It seems that our protein metabolism is linked to our appetite. So if there is anabolism like mTOR activation and downregulation of AMPK, which is essentially catabolic processes, that seems to stimulate an appetite suppressing response. Because it means that the body has consumed enough protein to fuel anabolism, and thereby we don’t need more protein. The result of that is that up to the point at which protein is still used for muscle protein synthesis, there is an improvement in satiety or a decrease in hunger when we consume more protein. But after that point when the protein starts being oxidized for energy, there is no further effect of higher protein intakes on our appetite. So the body essentially makes us seek out a certain protein intake, which also optimizes our body composition. Evolutionarily speaking, this makes perfect sense because unlike fats and carbs, our bodies do not have a very efficient method to store protein. You can store lean body mass, but it’s a very energy inefficient process. So it would be very convenient if we had some mechanism which would make us consume protein. However, we also don’t want that mechanism to disrupt our general appetite and make us starve ourselves or make us not eat carbs or fats when those are plentiful. Because we also, of course, don’t want to starve.
So protein leverage in evolutionary terms makes perfect sense if you think about it from the perspective of our bodies wanting us to consume a lot of energy, but also wanting to make sure that we consume enough protein in the process. Now, that’s a nice theory and all, but what about hard data? Well, it turns out that a meta analysis of 38 studies found very strong support for protein leverage. The meta analysis found that up to a protein intake of about 20% of energy intake. Looking at various previous studies, there was indeed a decrease in energy intake when you allow people to consume whatever they wanted. However, beyond the protein intake of 20%, there was no significant further decrease in energy intake. So there was a breakpoint at about 20% of energy intake, which corresponds to about 1.2g/kg per day, which so happens to correspond to the optimal protein intake for health and body composition purposes for non strength training individuals. So combined with our study we have evidence in sedentary and strength training individuals that the protein intake for maximum satiety quite closely corresponds with the protein intake for optimum body recomposition. Interestingly protein leverage appears to be much stronger in other animals than in humans. You see in some birds and rats and pigs that protein leverage is so strong that the animals will actually self-select diets with complementary amino acid profiles. If you allow birds to select their own diets, then the birds will select a protein intake that’s very closely corresponds to their requirements.
In conclusion, protein is more satiating than carbs and fats if and only if you have not yet consumed enough protein for optimum body recomposition. Most of my subscribers probably do consume enough protein already. So for them, the consideration is first and foremost, whether it makes sense to increase their protein intake even further when they are cutting to make fat loss easier via a lower appetite. It turns out that is not the case. And it’s also very strongly my experience that many other types of foods are a much better way to reduce your appetite when you already have enough protein in your diet. If you’re consuming white fish or chicken breast, or worst of all, whey shakes for the protein with the idea that, oh, that will reduce my appetite, that usually backfires quite horrendously. You are much better off investing those calories in fibrous carbs or foods that give you a lot more satisfaction which will also improve your diet adherence. In general, I strongly advise most of my students and my clients to focus on what I call the two S’s, which is satisfaction and satiety. You want both. If you have a diet that is satiating but not satisfying, it will be very hard to stick to even if you’re not hungry, because it’s not emotionally satisfying. Conversely, if you have a diet that is very satisfying, you like the foods that are in it, but it leaves you hungry, that is also not a long term sustainable solution. This knowledge increases your options because it means you don’t need to just stuff yourself with ever more protein, and it gives you options for other types of foods, vegetables, certain types of potatoes, beans, legumes can be great sometimes. And in general, low energy density, high food volume, high fiber foods. Those are great to suppress your appetite.
I hope this knowledge helps you with your fat loss diets, and if you like this type of evidence based fitness content, I’d be honored if you like and subscribe.