Leucine ‘Trigger’ per Meal Calculator
Check if this plate likely hits the leucine trigger
Leucine trigger, food choices and limits FAQ
What does this leucine per meal calculator do?
It takes your age band, main protein source and portion size, estimates how many grams of leucine are on the plate, and compares that to a practical per-meal trigger band for muscle protein synthesis. You see whether the meal is likely below, around or above that range.
What is the “leucine trigger” or threshold?
Research suggests that roughly 2.5–3 g of leucine per meal is enough for most adults to maximally stimulate muscle protein synthesis, after which extra leucine stops adding much extra signal. This is often called the leucine threshold or trigger for a given meal.
Why does age matter in this calculator?
With ageing, muscles can become a bit less sensitive to amino acids, a concept sometimes called anabolic resistance. Many experts suggest that older adults may benefit from slightly higher protein and leucine per meal, so the tool nudges the “ideal” band a little higher for the 60+ option.
Where do the leucine numbers for each food come from?
The calculator uses typical leucine per 100 g values from food composition tables and sports nutrition summaries for foods like chicken breast, beef, tofu, beans, milk and whey protein. They are averaged and rounded to stay practical, so numbers are estimates, not lab results.
What if I combine several protein sources in one meal?
This simple version assumes one main protein source. In real life you might combine chicken with beans and yogurt, for example. In that case, treat the result as a minimum estimate and remember that total protein, not leucine alone, still matters for your day.
Does hitting the leucine trigger guarantee muscle gain?
No. Hitting a per-meal leucine target is only one part of the picture. You still need enough total protein, calories, resistance training, recovery and consistent habits. The trigger idea is mostly about making each significant meal count for muscle maintenance and growth.
Who should be extra careful with high-leucine meals or supplements?
Anyone with kidney disease, advanced liver disease, complex medical conditions, pregnancy, or a history of eating disorders should treat this as background education only and work closely with their healthcare team before changing protein or supplement routines.
How to use this leucine trigger per meal calculator
This page turns a single plate or shake into a rough estimate of leucine per meal. Instead of guessing whether a portion of chicken, tofu or whey “is enough”, you get a simple comparison to a practical 2.5–3 g leucine band that many studies use when designing muscle protein synthesis protocols.
1. Pick the age band that best fits you
Start by choosing whether you fall into the “Under ~60 years” or “Around 60+ / older” category. The underlying research often uses similar leucine targets across adulthood, but older adults may benefit from slightly higher per-meal protein, so the tool nudges the ideal band upward for the 60+ option.
2. Choose the main protein on the plate
Next, select the food that contributes most of the protein in the meal. For example:
- Use whey protein powder if the meal is mostly a shake.
- Pick chicken breast or beef for meat-based plates.
- Choose firm tofu or beans / lentils for plant-based meals.
- Select skim milk for a milk-based drink or cereal bowl.
If your meal mixes several options, select whichever one contributes the biggest chunk of grams of protein and treat the result as a conservative estimate.
3. Enter the cooked portion size in grams
Add the cooked weight you would see on the plate in grams, such as 120 g chicken or 150 g tofu. You can read this from a food scale, a package label, or a sensible estimate from typical serving sizes. All calculations use grams, which matches how leucine content is usually listed in food composition tables.
4. Read the leucine grams, trigger band and status
After you hit Estimate leucine per meal, the summary shows:
- Estimated leucine (g) from that portion of the chosen food.
- A trigger band based on your age selection, usually around 2.5–3 g for younger adults and a slightly higher ideal for older adults.
- A simple status line (below, around or above the practical trigger band).
All leucine values are in grams to keep comparisons straightforward.
5. Copy the summary into training or diet notes
Use Copy summary to paste the result into coaching notes, a training log or a nutrition check-in form. That way you and your coach or clinician can see how often your main meals likely cross the leucine trigger without re-running the numbers every time.
6. Use the tool as a guide, not a strict rule
Remember that these numbers are approximations, based on average leucine content and simplified target bands. If you are recovering from illness, cutting calories hard, managing chronic disease or working through a complex training block, let this calculator sit alongside individualised advice from your healthcare and coaching team instead of replacing it.
Over weeks and months, aim for a pattern where your main meals are reasonably high in total protein and leucine, rather than chasing perfection at every single plate.
How the leucine trigger per meal math works
Under the hood this calculator combines food composition data with a simple per-meal leucine target band. It does not do anything magical, but it saves time when you are planning meals around training or recovery.
1. Working in grams
Portions are entered directly in grams, which matches most leucine tables that list values per 100 g of food. This keeps the calculations and the output in the same unit and avoids confusion around conversions.
2. Using typical leucine per 100 g values
Each protein source in the dropdown has an assigned leucine per 100 g number, based on ranges reported in nutrition databases and sports nutrition articles. For example, chicken breast is treated as roughly 2.5–2.7 g leucine per 100 g, firm tofu around 1.4–1.5 g, and whey protein powder roughly 10 g per 100 g of powder.
The calculator applies a simple proportional formula:
Estimated leucine (g) = (portion in g × leucine per 100 g) ÷ 100
Results are then rounded to one decimal place to keep them easy to read.
3. Setting the practical trigger band
Several studies and reviews suggest that, for most adults, a meal containing about 2.5–3 g of leucine is enough to maximise the muscle protein synthesis response. The tool therefore treats:
- Below ~2.5 g as “likely below full trigger” for many adults.
- Around 2.5–3.5 g as “around the practical trigger” band.
- Above that as “above trigger”, where extra leucine probably does not add much extra signal on its own.
For older adults the “around” band is nudged slightly higher to reflect the idea of anabolic resistance.
4. Building the status line and summary
Once the calculator has your estimated leucine per meal and an age-specific trigger band, it labels the meal as:
- Below trigger if it falls clearly under the band.
- Roughly at trigger if it lands inside the band.
- Above trigger if it clearly exceeds the band.
The copyable summary then strings together your age band, protein choice, portion size, estimated leucine and status into a short paragraph you can paste elsewhere.
Because food composition and individual needs vary, all of this math should be viewed as approximate guidance, not exact prescription. Any personalised nutrition or medical plan you already have always comes first.
References and further reading on leucine per meal
These resources discuss leucine-rich foods and per-meal leucine targets used in muscle protein synthesis research:
- CompareWhey — Leucine Threshold Guide — explains the leucine threshold concept and notes that many protocols aim for roughly 2.5–3.0 g leucine per meal to maximise muscle protein synthesis.
- Frontiers in Nutrition — Impacts of protein quantity and distribution on body composition — describes meal patterns designed to deliver at least about 2.5 g leucine at each meal in adult women when studying protein distribution and muscle outcomes.
- Myprotein — What is leucine? Benefits, dosage and sources — lists approximate leucine content per 100 g for foods like chicken breast, beef, tofu, eggs and milk, which this calculator uses as a practical starting point.
Use these as background reading, then work with your own healthcare and coaching team on protein and leucine targets that fit your health, training and preferences.