- The percentage of protein in your diet is highly correlated with how much food you will consume.
- Given the opportunity, we gravitate to foods that are highly processed hyperpalatable junk food that typically contain less protein and more easily accessible energy from carbs and fat.
- Rather than eating more protein, it’s more important to focus on cutting back on processed carbs and fat which leads to an increased percentage of energy from protein and greater satiety per calorie.
- The fundamental reason that high protein diets lead to weight loss is that there are more losses converting protein to energy. Not only do we eat fewer calories, but less of the energy is available to be stored as fat.
Protein % vs satiety
The chart below shows the percentage of protein vs satiety response curve from our analysis of the food diaries from sixty thousand people using Nutrient Optimiser. We can see clearly that Optimisers who consume a higher percentage of protein tend to eat significantly less across the day.
The impact of the percentage of protein on energy intake is massive! People eating a higher percentage of protein tend to eat up to 60% fewer calories!
However, unless you’re working out like Arnie, it’s not simply about eating more protein (which can come packaged with a significant amount of low-satiety fat).
Sustainable weight loss is more about avoiding heavily processed, easily accessible energy from non-fibre carbohydrates and fat rather than simply consuming more protein.
In our previous satiety analysis, we identified the dominant factors that influence satiety by analysing half a million days of MyFitnessPal data. It was clear that we tend to overeat foods that are a combination of starch and fat while we naturally eat less when we focus on foods that have more protein and fibre.
Now, using sixty thousand days of detailed food diary data logged in Cronometer (i.e. both macronutrients and micronutrients) from more than a thousand Optimisers, we have validated our previous analysis of the satiety response to macronutrients. Additionally, we have gained a powerful understanding of the degree to which micronutrients drive us to eat more or less than we would like to.
This analysis empowers us to emulate the behaviours of people who avoid the common pitfalls of nutrition.
This is the first of an eight-part series:
- Part 1 – Why does protein suppress your appetite? <- You Are Here
- Part 2 – Carbohydrates, fat, fibre, energy density, sugar, starch, alcohol & water
- Part 3 – Which fats make you skinny?
- Part 4 – The effect of minerals on hunger and satiety
- Part 5 – Which vitamins (and how much) do you need for weight loss?
- Part 6 – Optimal amino acid intake for satiety and weight loss
- Part 7 – Optimal Nutrient Intakes (ONIs)
- Part 8 – The Optimal Nutrition Score
The word protein comes from the Greek word proteos, which means “of first importance.” So it’s only fitting that we should devote this first article to the satiety impacts of protein.
The data comes from people trying to live their best life in the real world. They are not a controlled metabolic ward where their food choices are controlled. They are subject to the same stresses, temptations, beliefs, trends and diet fads (just like you).
Using big data enables us to identify trends and identify the factors that have the most significant impact on our tendency to eat more or less than we would like to.
We are often confidently wrong!
When it comes to understanding nutrition and satiety, we often get lost in the minutiae of biochemistry and endocrinology. We try to explain the mechanisms of what we believe will happen based on the action of hormones and peptides such as insulin, glucagon, leptin, ghrelin, CLP-1, CKK & PYY, etc..
Unfortunately, this ‘understanding’ often leads us confidently and adamantly down the wrong track. Our limited knowledge of biochemistry and endocrinology also don’t give us much practical information about what we should eat.
We want to empower you to make more informed decisions about food quality to reduce the burden of micromanaging food quantity and constantly fighting your appetite.
The basal metabolic rate (BMR) (or the number of calories required to maintain weight) for each Optimiser was calculated using the Katch Mcardle Formula using their weight and body fat entered into Cronometer and uploaded to Nutrient Optimiser.
The vertical axis on the satiety response curve below represents the users’ reported calorie intake for a particular day divided by their BMR.
- If the value is greater than 100%, we can assume they consumed more than their BMR.
- If the value is less than 100%, it means they ate less than their BMR.
In the example of protein below, we can see that people who at less protein tended to eat more than 20% above their BMR (which would lead to weight gain), while people who consumed a higher percentage of protein tended to eat up to 40% below their BMR (which would lead to weight loss).
What happens to ‘excess protein’?
You may have noticed in the chart above that the increase in satiety does not occur until we beyond 15 to 20% protein. It appears that the initial intake of protein is “skimmed off the top” for muscle protein synthesis, growth and repair.
Professor Stuart Phillips likes to talk about protein as the building blocks of your body.
The first portion of your protein intake is not available to be used for energy, but rather is used to repair and maintain your essential bodily functions.
For someone who is active or doing a lot of resistance training, this ‘tipping point’ may be higher (say up to 30%), while it may be lower if you are sedentary (perhaps as little as 10%).
As we eat more protein beyond our minimum requirement, some of this ‘excess protein’ is converted to heat, some is excreted in the urine, and some is used for increased muscle protein synthesis and cellular repair.
But, as your craving for protein is satisfied, your appetite for high protein food starts to decrease. While you may find room for a easy energy from a doughnut or a cookie, you’re less likely to want more lean protein.
Protein overfeeding studies consistently find that it is hard to gain weight when eating a lot of protein. This is partly because of the increased losses involved in converting protein to usable energy. But, it’s also tough to maintain a very high protein intake for a significant amount of time because of the powerful satiety response.
The observed satiety effect of protein in the data from Optimisers aligns with the Protein Leverage Hypothesis, which suggests that:
- we consume more food until we obtain the protein we need, and
- once we get enough protein, our appetite reduces and we go in search of foods that contain more easily accessible energy (e.g. refined fat and carbs).
Oxidative priority and thermic effect of food
The table below (adapted from Cronise et al., 2017) shows:
- the order in which the different components of our food are used in your body (oxidative priority),
- what they are used for,
- their storage capacity, and
- their thermic effect.
Because we have negligible storage capacity for them in our bloodstream, alcohol and ketones are used for energy first, followed by ‘excess protein’, then by carbs and fat.
If you have plenty of fat and carbs available, your body may even use those easier energy sources first and excrete some protein in the urine because it’s harder to convert to ATP.
Although carbs and protein can be converted to fat, it is usually the dietary fat that is stored on your body because it is last in line to be burned. Fat also requires less insulin to hold in storage, so it can easily be stored easily.
The thermic effect of food is the amount of energy that is lost to heat in converting that particular food to usable energy in your body (i.e. ATP). Protein has a more complex chemical structure than carbs or fat, so it takes more energy to break the carbon bonds to unlock the energy to be used in your body. This thermic effect of food contributes to keeping you warm, but some people can even experience ‘meat sweats‘ when they eat a lot of protein.
It’s important to note that there is a range of thermic effect of protein-containing foods. A protein powder that is easy to digest may have a thermic effect of 20%, while a piece of raw liver or kidney which is more complex may incur 35% losses in conversion to usable energy.
Similarly, there is a range of thermic effect for carbs. Acellular carbohydrates such as sugar or refined flour may be quickly and easily converted to ATP because they are effectively predigested, while an uncooked piece of broccoli or spinach will require more effort for your body to access the energy.
What about the official protein recommendations?
Shown on the protein-satiety response curve are:
- the average population intake,
- the Estimated Average Requirement (EAR) for protein,
- the Recommended Daily Intake (DRI), and
- the average of the Optimisers,
- a ‘stretch target’ for protein.
How much protein do you need?
Your appetite works to ensure you get a minimum amount of protein. As shown in the chart below (from Lemon, 1991), endurance athletes require a minimum of around 1.4 g/kg BW to maximise recovery, while a strength athlete will benefit from at least 1.8 g/kg BW. If you’re not particularly active, you won’t need as much protein. You can consider this to be the minimum amount of protein required for muscle growth and recovery.
What if you’re losing weight?
Because your body is only too willing to offload metabolically expensive muscle, you should target a higher protein intake if you are trying to lose weight (both in grams and percentage terms).
The chart below from a review paper by Stuart Phillips shows that the muscle preservation benefits of protein are maximised at around 2.6 g/kg of body weight (BW) for someone who is in a significant deficit and doing resistance training.
But it’s not just about eating more protein!
As shown in the chart below, simply consuming more protein correlates with a higher overall energy intake. If your goal is to lose body fat, you need to ensure you don’t get too much low satiety energy-dense dietary fat along with your protein.
The real satiety benefit comes from reducing the fat and carbs in your diet, which leads to an increase in protein percentage.
What’s a reasonable target for protein?
To help you understand what is “normal”, we have analysed the protein intake in a number of ways.
The protein distribution histogram chart from our analysis of Optimisers below shows that the most common protein intake is 20-25%, with an average of 28%. Few people manage to sustain a protein intake above 50%. In our Nutritional Optimisation Masterclass, we tend to find that people who consume between 40 – 50% of their calories from protein tend to achieve the best weight loss with less hunger while preserving precious lean muscle mass.
The chart below shows the distribution of protein intake in terms of g/kg LBM. The average protein intake of Optimisers is 2.0 g/kg LBM or 1.5g/kg body weight (BW).
The table below shows the 25th percentile protein intake along with the average and 85th percentile for each of these ways of measuring protein intake.
A calorie is not a calorie!
We thought it would be interesting to dig into this concept a little further, to run the satiety analysis in terms of net energy (i.e. after muscle protein synthesis and losses due to dietary-induced thermogenesis), assuming:
- protein up to 15% of your Basal Metabolic Rate will be used for muscle protein synthesis,
- ‘excess protein’ not used in muscle protein synthesis yields 3.2 calories per gram (assuming a 20% thermic effect),
- non-fibre carbohydrates yield 3.8 calories per gram (assuming a 5% thermic effect),
- dietary fat yields 8.7 calories per gram (assuming 3% thermic effect), and
- fibre yields two calories per gram.
The chart below shows the relationship between energy intake and “net energy” intake (i.e. the energy available after muscle protein synthesis and losses due to dietary-induced thermogenesis).
The next chart shows percentage protein and percentage available energy together on the same chart. A reduction in the available energy from your food has a much stronger effect than even protein.
While protein has a significant effect on our satiety, the net energy available after losses seems to have an even greater impact on the number of calories we consume.
While taking your percentage of protein from one extreme to the other can have a 65% impact on your calorie intake, our analysis of data from Optimisers indicates that a lower net energy availability in your food (i.e. higher dietary-induced thermogenesis) can have a massive 75% impact on your calorie intake!
To unpack this a little more, the table below shows the calories in each macronutrient if you burned the food in a Bomb Calorimeter (i.e. one calorie raises the temperature of one millilitre of water by one-degree Celsius). The dietary induced thermogenesis (DIT) is the amount of energy that is lost in the conversion of each macronutrient contained in food to energy to be used in your body (ATP) or storage as fat.
|macro||calories/g||DIT assumed||DIT range||energy yield (cal/g)|
|protein||4||20%||20 to 35%||3.20|
|carbs||4||5%||5 to 15%||3.80|
|fat||9||3%||3 to 15%||8.73|
As noted above, there is a range of dietary-induced thermogenesis for each macronutrient that would depend on the degree of processing (i.e. a raw food would require more energy to process in your body to use for ATP while a cook or highly processed food would require less). If you wanted to maximise the thermic effect of food and minimise the calorie yield, you should prioritise minimally processed foods that contain less easily accessible energy from carbs and fat and more protein and fibre).
The first part of the protein you eat will not be available for use as energy (up to around 15% of your BMR) but rather ‘lost’ to muscle protein synthesis to build and repair your body, create neurotransmitters and all the other vital functions of protein.
The rest of the protein you eat can be used for energy if required, but some may be excreted, and a significant amount will be used converting that protein to usable energy in your body.
Because this conversion process is so energy-intensive (with up to 35% losses) and because your appetite is optimised to obtain the maximum amount of energy with the least effort, your appetite will guide you to more efficient sources of energy such as highly processed carbs and fats.
Your appetite increases to make the most of any opportunity to get easy energy when it is available, especially if you are hungry and have not already filled up on nutrient-dense high satiety foods.
Our modern food processing effectively pre-digests your food for you so you can get more energy with less effort.
A recent study by Kevin Hall showed that people tend to eat significantly more calories and gain weight if the food is heavily processed (even when matched for macronutrients and calories). We gain more weight when we eat processed foods because they have lower dietary-induced thermogenesis and hence (calorie for calorie) more energy is available to be stored as fat.
Not only do we tend to overeat foods that are heavily processed, but we are also able to obtain a lot more energy from them because of the reduced losses in converting that food into energy (i.e. lower thermic effect of food).
So, once you have obtained your minimum protein required for muscle protein synthesis, if you want to reduce your overall energy intake without counting, weighing and measuring everything you eat, you need to focus on less efficient energy sources.
Foods and meals that contain more protein and fibre with less fat and non-fibre carbohydrates will be less efficient and provide more satiety. Your appetite for these foods will switch off earlier, while foods and meals that contain more fat and carbs are less efficient and will cause you to consume more energy.
Some worked examples
To help you understand how this works in practice, let’s look at some examples.
The table below shows the macro split of the average of the data from Optimisers. In the first row, we have protein from which we ‘lose’ 15% for bodily functions, and have 80% of the remaining amount left for usable energy. We lose 5% of the net carbs to dietary-induced thermogenesis and have 14% left. Similarly, for fat and fibre. In the end, we have 75% of the calories originally eaten to make ATP or to be stored as body fat after 25% of the calories consumed are used for muscle protein synthesis and lost in the conversion to energy.
In the next example, we have the population average macronutrient split. In this scenario, all of the protein will be used for muscle protein synthesis with none left over to be converted to energy. In the end, we have 84% of the calories consumed available for energy or to be stored as fat. Compared to the Optimiser average, 9% more of the energy ingested is available for conversion to ATP or storage as body fat).
The most nutrient-dense foods
In this last example, we have the most nutrient-dense foods, which not only contain a lot of nutrients, but also a significant amount of protein and fibre.
Although the dietary-induced thermogenesis for each macronutrient would likely be higher because the nutrient-dense foods are typically less processed, we have used the same DIT values.
In this scenario, we end up with more leftover energy from the ‘excess protein’, but a lot less available energy from fat and non-fibre carbs. So the available net energy is calculated to be 66%. The net energy value aligns with the lowest value we see in the data from Optimisers.
The chart below shows the Optimiser average and the population average along with the net energy available from the foods that have the highest nutrient density. Not only would you be consuming around 60% fewer calories by prioritising nutrient-dense minimally processed food, but you will also absorb a lot less of those calories while still obtaining the micronutrients you need to thrive!
To make this a little more relatable, the table below shows the macronutrients and the calculated net energy for a number of popular dietary approaches. The macronutrient profile is based on our nutrient-dense food lists for various goals, so they are the best versions of each of these approaches.
|approach||protein||net carbs||fat||fibre||net energy|
|max nutrient density||42%||17%||23%||18%||66%|
The net energy for each approach is shown in the chart below. Because they all tend to move you away from processed food that tends to contain more protein and fibre, we end up with diets that yield a lot less net energy (i.e. after muscle protein synthesis and dietary-induced thermogenesis).
How to implement a high satiety diet
One ‘problem’ with higher protein intake is that abrupt changes can force a significant and uncomfortable energy deficit which, in spite of increased satiety on a calorie for calorie basis, is still not going to be easy! Hence, in the Nutritional Optimisation Masterclass, we guide you to find your current baseline and then slowly dial in your macros to ensure you are getting the results you want in terms of blood sugar control, weight loss, fat loss and gaining lean muscle mass.
If you are looking to lose body fat, the ideal approach would be to increase your percentage protein slowly and continue to refine your diet until you get the results you want.
You can think of Dietary Induced Thermogenesis as resistance training for your metabolism. If you’re not getting the results you want, then you may benefit from a little more.
Rather than just prioritising protein, it’s ideal to focus on high satiety nutrient-dense foods and avoid foods that are a combination of fat and carbohydrates together.
Where do I start?
After four years of digging into the theory, we’ve created some exciting tools to help you optimise your nutrition:
- Nutritional Optimisation QuickStart Guide (free download)
- Food Lists optimised for your goals (free download)
- Nutritional Optimisation Program
- Nutritional Optimisation Masterclass
- Food list bundles
Our series of 22 nutrient-dense recipes have used this refined understanding of satiety to create the best versions of recipes tailored to suit different goals.
The recipes in the high protein:energy recipe book are designed to maximise the satiety effects of protein to smash your hunger and help you to feel satisfied with fewer calories.
In our next article in this series, we will look at the satiety response to carbohydrates, fat, sugar, alcohol.
- Part 1 – Why does protein suppress your appetite?
- Part 2 – Carbohydrates, fat, fibre, energy density, sugar, starch, alcohol & water <- Read this next
- Part 3 – Which fats will make you skinny?
- Part 4 – The effect of minerals on hunger and satiety
- Part 5 – Which vitamins (and how much) do you need for weight loss and satiety?
- Part 6 – Optimal amino acid intake for satiety and weight loss
- Part 7 – Optimal Nutrient Intakes (ONIs)
- Part 8 – The Optimal Nutrition Score