12-Week Skin Diary

Most skin products need about three months to show what they can do, yet most of us judge them in a week, change three things at once, and never know what actually worked. The 12-Week Skin Diary gives every product a fair test: one change at a time, photos in the same light, and a clear decision at week 12.

Each evening takes two minutes. Each week opens with two short pages of science, one thing to remember and one small experiment. No brand names, no "whitening", no hype: just what the research says, and a record of what your own skin says.

How it works

1. Day 0Audit your shelf, sort it into three baskets and pick the one product you will test.
2. Every eveningTwo minutes: tick your routine, score irritation and note sleep and stress.
3. Every weekRead two pages of science and review the week. Take photos at weeks 4, 8 and 12, then decide at week 12.

What you get

• 84 daily pages (12 weeks of 7 days): tick your routine, score irritation 0–3, mark each day done, half or missed, in about two minutes
• 12 weekly science spreads, one topic a week: sunscreen, retinoids, moisturizers, serums, irritated skin, beauty supplements, adult acne, dark spots and melasma, and more
• 42 claims graded with 4 evidence labels (Strong, Moderate, Debated, Unproven)
• An ingredient guide with 27 entries, plus the Three Baskets system: Worth it, Depends on you, Skip it
• 16 tool pages, including a 12-week product trial log, an eight-week retinoid start, a 7-day arm test and a week-12 shelf audit
• Photo check-ins at weeks 4, 8 and 12, with a side-by-side verdict page: keep, stop, or see a doctor
• 5 safety checks before you start, 31 "when to see a doctor" flags, and a quick lookup for when something goes wrong
• Two pages to tell your skin story clearly at a dermatologist appointment
• Worked examples and the 11 most common mistakes, with what to do instead
• 37 study sources listed week by week