While many people are familiar with the individual vitamins and minerals, most of us don’t give much thought to the individual amino acids that make up protein.
Following on from the analysis of the essential vitamins, minerals and fatty acids, this article looks at our satiety response to the different amino acids to determine optimal stretch targets.
- Part 1 – Why does protein suppress your appetite?
- Part 2 – How do carbs, fat, sugar, alcohol and starch stimulate your appetite?
- Part 3 – Which fats will make you skinny?
- Part 4 – Minerals
- Part 5 – Vitamins
- Part 6 – Amino acids <- You Are Here
- Part 7 – Optimal Nutrient Intake
- Part 8 – The Optimal Nutrition Score
Due to the unique functions of each of the amino acids, there are specific minimum target levels for each of them. The table below shows the minimum levels set by the World Health Organisation (WHO) for each amino acid to prevent deficiency.
|Amino acid(s)||WHO mg per kg body weight||WHO mg per 70 kg||US mg per kg body weight|
|Methionine+ Cysteine||10.4 + 4.1 (15 total)||1050 total||19 total|
|Phenylalanine+ Tyrosine||25 (total)||1750 total||33 total|
If you’ve been keeping up with this series you’ll be aware that we have a very strong satiety response to a higher proportion of energy in our diet.
The chart below % protein intake versus calorie intake divided by the basal metabolic rate (BMR) for forty thousand days of food diary logs from more than a thousand people. People who consume a larger proportion of their energy from protein achieve a massive 64% energy deficit compared to those who consume less protein!
The average protein intake of Optimisers is 28% while the 85th percentile intake is 40% (i.e. only 15% of people are consuming more than 40%). The chart below shows that there is a wide distribution of protein intake represented in the data. Very few people are consuming less than 10%, while at the other extreme, a few people are getting more than 50% of their energy from protein. If you are looking to lose weight by increasing satiety, you could aim for a stretch target of 40% protein or more to maximise satiety.
To dig a little deeper into the satiety response to protein, the rest of this article looks at the satiety response to each amino acid.
Satiety response to amino acids
The charts below show the satiety response to the individual amino acids, including:
- the average intake of Optimisers,
- our recommended stretch target, and
- the World Health Organization’s Recommended Daily Intake level to prevent malnutrition.
In a few cases, there is an inflection point where a higher intake does not provide significantly more benefit. Where this is the case, we have used this to define our stretch target. Where there is no distinct change, we have set the stretch target to align with the 85th percentile intake of Optimisers. This will be a challenge, but still achievable with food.
The charts below are accompanied by a brief description of the function of each of the amino acids. If any of the benefits or deficiency conditions are more important to you, you could initially focus on achieving the stretch target for that amino acid.
Cystine is required for the synthesis of insulin, skin, hair, biotin, glutathione, taurine and sulphate. It also helps with the detoxification of chemicals and has antioxidant properties and lowers insulin resistance. A lack of cystine is associated with poor immune function, aging, cancer, a decreased ability to process drugs and toxic chemicals, and poor wound healing.
Foods that contain more cysteine include egg whites, beef, pork and whey protein.
Your body uses histidine to regulate and use iron, copper, molybdenum, zinc, and manganese. A lack of histidine is associated with allergies, poor hearing, heavy metal toxicity, schizophrenia, hypertension, Parkinson’s Disease, poor memory, rheumatoid arthritis, and thyroid issues.
Isoleucine helps to heal muscle tissue, boost energy levels and assists in recovery from strenuous physical activity.
Leucine is critical for muscle protein synthesis, stimulates the release of anabolic hormones that help in the regulation of blood sugar, promotes the growth and the recovery of muscle and bone tissues, as well as the production of growth hormone.
Foods that contain more leucine include egg white, seaweed, cod and cottage cheese.
Lysine is a necessary building block for all proteins in your body and plays a major role in calcium absorption. Lysine is essential for muscle growth and is used to form carnitine, which helps transport fats across your cells to be used for energy. A deficiency of leucine is associated with anemia, fatigue, poor concentration, loss of bone calcium, tiredness and infertility.
Foods that contain more lysine include haddock beef, shrimp, prawns, chicken, turkey and halibut.
Methionine contains sulphur and can produce other sulphur-containing molecules in the body.
Foods that contain more methionine include egg white, egg, haddock, prawns, shrimp and cod.
While we don’t have data on glycine, it is worth a mention as a conditionally essential (i.e. your body can make enough of it some of the time) amino acid that is contained in connective tissue.
It’s crucial to get adequate glycine to balance your methionine intake. Glycine provides a range of benefits, including sleep and improved skin. It’s also has a sweet taste, so some people use it as a sugar replacement in their drinks.
Foods that contain more glycine include chicken breast, molluscs, lungs, pigs feet, pigs ears, lobster, shrimp and prawns.
Phenylalanine is a precursor of tyrosine that works as an appetite suppressant. It helps with the production of dopamine with improves your levels of satisfaction with your food (as well as the rest of your life) and also enhances your learning and memory.
Foods that contain more phenylalanine include egg white, prawns, shrimp, haddock and cottage cheese.
Threonine supports cardiovascular, liver, nervous system, and immune system function. It also plays a role in the formation of tooth enamel, collagen and elastin in your skin and is as a precursor to glycine. A lack of threonine is associated with confusion, digestive issues, agitation, fatty liver and depression.
Foods that contain more threonine include beef, haddock, pollock, cod and tuna.
Tryptophan is a precursor of niacin, melatonin (which helps you sleep) and serotonin (which makes you happy). Tryptophan also suppresses sweet cravings and appetite. Deficiency of tryptophan is associated with anemia, anxiety, depression, decreased serotonin, fatty liver, insomnia, poor concentration, and suicidal thoughts.
Tryptophan is one amino acid that has a very strong initial satiety response that levels out once you get around 2 g/2000 calories.
Tryptophan is contained in egg whites, greek yogurt, crab, mozzarella cheese, and crayfish.
Tyrosine improves cognition and working memory under stressful conditions, improves exercise tolerance in the heat, and is a precursor to thyroid hormones. A lack of tyrosine is associated with low blood pressure, low body temperature, restless legs, stress, exhaustion, poor memory and apathy. Tyrosine is another amino we see taper off once we get above 6 g/2000 calories.
Foods that contain more tyrosine include cottage cheese, salmon, shrimp and beef.
Valine calms emotions, enhances immune function, and improves muscle coordination.
Foods that contain more valine include egg white, cottage cheese and halibut.
Comparison of response to amino acids
The chart below shows the satiety response curves for all amino acids combined.
Generally, the amino acids tend to behave as a group with a similar response (at least compared to the fats and minerals which show different levels of satiety response).
To the right of the chart, we see lysine and leucine, which make up a large proportion of the amino acid intake.
Zooming in on the smaller amino acids, we see that we get more of a bang for buck satiety response from cysteine, methionine, and phenylalanine (i.e. straighter lines), while we reach a minimum effective dose-response for tryptophan, histidine and threonine (i.e. there is more of a kink in the line).
Stretch targets for amino acids
If you’re eager, you could chase the stretch target all of these amino acids in your diet at once. Once you hit the stretch target for a particular amino acid, you could turn your focus to the other amino acids.
Alternatively, some of the conditions associated with each of the amino acids may resonate with you so you may choose to focus on a couple of amino acids initially.
To help you apply this information, the table below shows:
- a suggested stretch target for increased satiety for males (assuming 2000 calories per day) and females (assuming 1600 calories per day) for each amino acid,
- a suggested stretch target in terms of g/kg body weight, and
- a comparison between the stretch target and the WHO minimum Dietary Recommended Intake to prevent disease.
It’s worth noting that the stretch targets that align with greater satiety are around six times the recommended minimum levels!
|nutrient||stretch (male)||stretch (female)||g/kg BW||% DRI|
|glycine||4 g||3 g|
How is this useful?
Overall, as long as you are focusing on complete proteins from nutrient-dense whole food sources, there may not be a lot of use in focusing on individual amino acids (e.g. BCAAs).
If your goal is to achieve optimal health (rather than just avoiding diseases of deficiency), you should initially refine your diet to hit your target protein intake given by the Nutrient Optimiser Free Report.
But once you are able to routinely achieve your protein target, you can enter these amino acid stretch targets in Cronometer (as shown below) and work to level up your nutrient density using Nutrient Optimiser.
Where do I start?
After four years of digging into the theory, we’ve created some exciting tools to help you optimise your nutrition:
- The most popular foods optimised for different goals bundled with a QuickStart Guide to help you implement it (free download)
- Nutrient Optimiser Free Report
- Nutritional Optimisation Program
- Nutritional Optimisation Masterclass
- Food list bundles
- Nutrient-dense optimised recipes to suit your goal
In our next article in this series, we’ll be bringing all this together to look at the Optimal Nutrient Intake for all of the essential micronutrients to enable you to, rather than prevent the diseases of deficiency, target the nutrient intake from food that aligns with optimal health.