How Tulsy works: the Energy Forecast, Longevity Reserve and Combined State

Tulsy is built around manual logging, which takes under two minutes a day. No wearable is required. If you use Apple Health or Google Fit, Tulsy can auto-fill steps and exercise, and you can identify meals from a photo.

The Energy Forecast is a daily score from 0 to 100 that estimates how much usable energy you are likely to have. It is predicted the night before, so you can plan, and refined as you check in through the day.

Conceptually, it combines three things: what you logged recently, where you are in your cycle, and how today's signals compare with your own recent normal. A short night means something different on day 3 of your cycle than on day 24, and something different again for someone whose baseline sleep is six hours versus eight.

The score also shows its main drivers, so you can see why a forecast is high or low rather than just the number.

Tulsy compares you with yourself, not with a population average. Your baseline is built from your most recent 14 days of logs and keeps rolling forward. That is why your first forecast appears on day one, but meaningful personal patterns usually emerge within 7 to 14 days.

Using a personal baseline means a signal is read as unusual only if it is unusual for you.

Energy, sleep, recovery and stress tolerance vary across the menstrual cycle for many women. When you are cycling, Tulsy uses your cycle phase as context, so an expected dip is not treated as a failure and an unexpected one stands out.

Onboarding branches on your hormonal reality. If your cycles are irregular, or you are in perimenopause, menopause or post-surgical menopause, the model does not assume a regular 28-day cycle and relies more on your personal baseline and trends.

The Longevity Reserve is a rolling 30-day score that shows whether your capacity is building, holding steady or being drawn down. It looks across six areas: sleep, stress, nutrition, movement, recovery and gut health.

A single hard day barely moves it. A month of short nights, high stress and little recovery does. It is designed to show the trend that daily numbers hide.

When you add biomarker results, they give extra context to the areas they relate to, such as inflammation or metabolic health.

Combined State maps where your energy is today against the direction of your Longevity Reserve, and places you in one of five states:

Tulsy shows patterns and correlations in your own data. A correlation means two things moved together; it does not prove one caused the other.

The scores are not a diagnosis, a measure of disease risk, or a prediction of lifespan. They cannot detect medical conditions, and they are only as good as what you log. If you notice symptoms that worry you, or a pattern that does not feel right, speak with your GP or a qualified health professional.