Three things we learned this week. One that should change your morning, one that should change your breakfast, one that should change what you measure.
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| Today's minimum effective dose: pick a wake time and hold it through the weekend. Saturday matches Tuesday. Bedtime follows once mornings are anchored. | |||
| Sources: Windred et al, Sleep 2024 · Berry et al, Nature Medicine 2020 · Kaul et al, Obesity 2012 |
1. Wake time matters more than hours.
A 2024 UK Biobank study (Windred et al, Sleep, 60,977 adults, six years of wrist-sensor data) built a Sleep Regularity Index, scoring the probability you are asleep or awake at the same time on any two consecutive days. The most regular sleepers had 48 percent lower all-cause mortality, 57 percent lower cardiometabolic mortality, and 39 percent lower cancer mortality, compared to the least regular quintile.
The signal was stronger than total hours slept. Consistency mattered more than duration. The wellness internet has been selling 8 hours for a decade. The body was tracking something else.
The simplest way in: pick a wake time and hold it. Saturday matches Tuesday. Bedtime tends to follow once mornings are anchored.
2. The colonoscopy reads structure. The microbiome reads function.
Two different jobs. Most people only ever do one.
A colonoscopy looks at the walls of your gut, whether anything is growing where it should not. Important, every ten years from 45.
A microbiome test reads what the 100 trillion bacteria living inside you are actually doing to your blood sugar, blood fats, inflammation, and mood. None of which a camera can see. The PREDICT program at King's College London (Berry et al, Nature Medicine, 2020, 1,002 participants in PREDICT 1, with the broader cohort since expanded to tens of thousands) showed that two friends can eat an identical bowl of porridge with banana and honey, and one spikes to 180 mg/dL while the other stays under 130. Same breakfast, different bodies, different futures.
That is the kind of data that changes what you put in your body. Full breakdown and our notes on when to actually order the test in Monday's edition.
3. Over 35, the scale is the wrong instrument.
Body composition shifts even when weight does not. Two adults at the same weight can have entirely different aging trajectories.
Visceral fat is invisible to BMI but independently linked to cardiovascular disease, type 2 diabetes, and dementia. Sarcopenic obesity, the thin-fat phenotype with normal weight, low muscle, and high fat percentage, predicts worse outcomes than obesity alone. Bone density loss accelerates after 35, faster in women after menopause, and most adults never get a T-score until they fracture. Fat distribution matters too. Central (apple) raises cardiovascular risk. Gluteofemoral (pear) protects it.
A DEXA scan captures all four. Kaul et al, in Obesity in 2012, validated DEXA against CT for visceral fat at r = 0.93, which is why it remains the gold standard. It is also overdone. Quarterly scans chasing 0.5kg changes turn body literacy into anxiety. One scan in your late 30s sets a baseline. Every two to three years tracks the trend.
The number on the scale stays the same. The body underneath does not.