Nutrition Logging for Apple Health: Meals Next to Your Nights

Calorie counting has a known problem: people stop. Logging takes too long, and the numbers don't seem to lead anywhere. Metrya tries to fix both. Logging is quick, and every meal ends up next to your sleep, recovery and energy data, where it can explain something.

Four Ways to Log a Meal

Every AI estimate is editable. Fields are marked "estimated", you can change any number, or add a note like "no sauce" and let the AI refine the meal. Favourite meals can be re-logged in one tap with ×½, ×1 or ×2 portions, with no AI call at all.

Saved to Apple Health

Meals are written to Apple Health as dietary samples: energy, protein, carbs, fat and the extra nutrients when they are known. Metrya never writes a made-up zero for a nutrient it doesn't know. Because the data lives in Apple Health:

• Other apps you use can read it.
• Food you log in another app that writes to Apple Health shows up in Metrya too.
• You can edit a meal later. Metrya replaces the Apple Health sample and keeps the original time.

Macros Next to What They Affect

This is the part a normal food log can't do. Metrya already knows your sleep, recovery, heart rate and activity, so meals get context.

Net Energy: eaten versus burned

Net Energy is what you ate minus what you burned (resting plus active energy). It is shown against your target range, not against zero. If your goal is to maintain weight, the range sits around zero; if you chose a small deficit, the range moves down.

The running number is available all day. The app only gives a verdict ("in range", "under") in the evening, because you can't judge a whole day at 10:00. Workout calories are not counted twice: Apple Watch already includes them in active energy.

Food reactions: meals and the next night

Metrya looks at your evening meals (from 17:00): how late the last meal was, how many calories, the macro mix, and whether there was alcohol or late caffeine. It then compares the next night's deep sleep, HRV, resting heart rate and sleep efficiency with your own 28-day baseline.

Over a few weeks, this builds a Food Reactions ledger of your own patterns, for example "late meals: HRV about 8% lower the next night, across 9 nights". It shows associations in your data, not causes, and it says how many nights each pattern is based on.

Water and caffeine

Log water with one tap, free. With Pro, log coffee, tea and other drinks from a library: they count as fluid, and caffeine drinks also feed the caffeine tracker, which shows how much caffeine is still in your system at bedtime. See caffeine and sleep.

History That Reads at a Glance

Nutrition history starts with the last 7 or 30 days: a bar per day against your calorie goal, your daily average, how many days were on target and your macro split. Each day is one card with a small ring, your macros, water and meal photos. Going over your goal shows as a second, thinner lap on the ring, not as a red warning.

On Your Wrist and Home Screen

• Apple Watch: today's calories, protein, fat and carbs against your targets, updated live. See Metrya on Apple Watch.
• Widget: a calorie ring with protein, carbs and fat, read live from Apple Health.

Privacy

Your meals and health data stay on your iPhone and in Apple Health. Two things go online, and only when you use them: search words (or a barcode number) go directly to Open Food Facts to find products, and, if you choose a cloud AI with your own key, the meal description or photo goes directly to that provider. Nothing goes through a Metrya server. More on how Metrya handles data.

Limits

• Photo estimates are estimates. A model can't weigh food in a photo. Check portions, especially for oils, sauces and dense foods.
• Food reactions need time. A pattern needs enough evenings with and without that food. Early results are marked as thin.
• Net Energy depends on burned energy. Apple Watch estimates of calories burned can be off, so read the trend, not one day.
• Not a medical diet tool. For medical nutrition needs, work with a professional.