Counting Lysine Without Losing the Plot

By Priya Raman, Community · Published 12 August 2026 · 7 min read

Nobody hands you a manual for this. You come home from the metabolic clinic with a number — so many milligrams of lysine per kilogram per day — and a printed list of foods, and somewhere between the car park and the kitchen it stops being a number and becomes every single meal, forever.

I want to talk about the ordinary mechanics of it. Not the science; your team owns that. The mechanics. The bit where it's 5pm, one child is crying, the other is asking for toast, and you need to know whether toast is a yes.

The number is a budget, not a rule

The most useful reframe I ever got was from another parent in a support group, not from a professional. She said: stop thinking of it as a restriction and start thinking of it as a budget. You've got so much to spend today. You can spend it early on something your child loves, and eat leaner later. You can save some in case dinner goes sideways. What you cannot do is spend it twice.

That framing changes what you need from a tracker. You don't need a diary you fill in at bedtime and file away. You need a running balance — the same way you'd check a bank account before buying something. How much is left, right now, before I say yes to the toast.

Weigh the things that matter, estimate the rest

Early on I weighed everything, including a single grape, and I burned out inside a month. The version that survived contact with real life is coarser:

• Weigh, in grams, anything that carries real lysine. Bread, pasta, dairy, legumes, meat, the special low-protein products. A cheap digital scale is the single best purchase you'll make. Cups and spoons vary enormously; grams don't.
• Save a named serving for the things you make constantly. "One slice of the loaf we always buy" is a weight you measure once and then reuse. Krestrel lets you save servings on a food, so the everyday staples become a tap instead of a weighing.
• Don't sweat the near-zero foods. Precision on something that contributes almost nothing buys you nothing and costs you the will to keep going.

Consistency beats accuracy here, and by a wide margin. A log where every day was measured the same slightly-imperfect way still shows your dietitian a real trend. A log that's meticulous on good days and blank on hard ones shows nothing at all, because the hard days are exactly the ones worth looking at.

Get your dietitian's numbers into the app, once

Most families are handed a spreadsheet or a printed table of lysine values by their clinic, often specific to the products available where you live. Retyping that at 11pm is how mistakes get in. Krestrel takes a CSV import — either in the app or, for a big dietitian dataset, through the bulk import script — so the values you actually use become the values the app calculates from.

Two things worth knowing about how those values are stored:

• You can override a value for your circle only. If the brand of bread you buy differs from the reference figure, you correct it for your family without touching anyone else's food list. The app flags a value you've overridden so you can see at a glance which numbers are yours.
• Corrections don't rewrite history. This is the detail I'd most want a new family to know. When you log a meal, Krestrel calculates the lysine at that moment and stores the result on the meal itself. Discovering next March that a food's value was wrong will change what you log from March onward — it will not silently redraw last autumn's chart. Your history stays a record of what you recorded, which is the only thing that makes it worth showing anyone.

Log at the table, not at bedtime

Every parent I know who kept this up long-term logs in the moment. Not because they're more organised — because memory at 10pm is a liar, and a total you reconstructed from memory can't be used to make a decision you already made hours ago.

The friction is the enemy. Favourites and recently-used foods sitting in a quick-add strip; a partner or a grandparent able to log from their own phone into the same shared record; the running total updating as you go. Those are not conveniences, they're the difference between a log that survives a stomach bug and one that doesn't.

And if you're feeding overnight, make sure your tracker agrees with you about when a day ends — otherwise a 2am feed quietly lands on tomorrow's budget. We wrote about that separately in Why a 2am Feed Shouldn't Count as Tomorrow.

What to do about the day you go over

You will go over. A birthday party, a mislabelled packet, a grandparent being kind. The instinct is to delete the entry, or to not log the day at all, because the number feels like a grade.

Log it anyway. A logged over-target day with a note saying what happened is genuinely useful information for your care team — it's a data point with a cause attached. A missing day is just a hole, and holes are where anxiety grows. Write the note. Move on. Tomorrow has its own budget.

What I'd tell myself at the start

• Buy the gram scale on day one.
• Ask your dietitian for their food values as a file, not a printout.
• Log at the table, in the moment, imperfectly.
• Never delete a bad day.
• Let the app do the multiplication. You have enough to carry.