Valter LongoPhD · biogerontologist, Professor of Gerontology, USC
No, cap it at 12 to 14
What it rests onGallstone literature cited in his foundation's booklet; the observed pattern in centenarian populations of eating dinner before dark and breakfast on waking; and his own reading that breakfast-skipping is associated with higher cardiovascular mortality.
Source: fondazionevalterlongo.org ↗
David A. SinclairPhD · Professor of Genetics, Harvard Medical School
Yes, and longer is the point
What it rests onMechanistic work in yeast and mice on caloric restriction and sirtuins, plus human time-restricted-eating trials.
Source: lifespanpodcast.com ↗
Layne NortonPhD · nutrition scientist, coach, and competitive powerlifter
Says it depends, and that timing is a compliance tool rather than a metabolic lever
What it rests onControlled feeding trials in which energy balance dominates timing effects; his own reading of which outcome marker a study chose.
Source: hubermanlab.com ↗
Stacy T. SimsPhD · exercise physiologist and nutrition scientist
Cautions against, for women
What it rests onSex-differences literature in exercise physiology.
Satchidananda PandaPhD · circadian biologist, Salk Institute (affiliation as of 27 Jul 2026; resignation effective 13 Aug 2026)
Wrong question: pick a window, not a fast
What it rests onHis own randomised and single-arm trials in metabolic syndrome and shift workers, plus a stated melatonin mechanism: melatonin rises two to three hours before habitual sleep and suppresses insulin, so the same meal eaten later produces worse glucose control. His own review then grades that literature down as small, short and often single-sex.
Source: hubermanlab.com ↗
Dr. Daniel PompaD.C. (Life University, 1995) · not a physician, no active licence · health educator and programme founder
Yes, but build up to it
What it rests onReduced cellular inflammation, a growth hormone rise, and metabolic flexibility. He is explicit that adaptation takes time and that the window should fit your schedule, not a protocol
Source: drpompa.com ↗
Panda's arrival collapses most of this fight rather than widening it. His 8 to 10 hour target overlaps the short end of Sinclair's 8-hour window and the long end of Sims's 12 to 13, and his 12-hour floor sits inside both Longo's cap and Sims's range. The six positions genuinely diverge on only two questions.
First, where the window sits: Sinclair compresses off the front of the day and skips breakfast, Panda and Longo compress off the back and keep a morning meal, and Panda's melatonin argument makes that a mechanistic disagreement rather than a preference.
Second, whether anything happens beyond eating less: Norton says no, Panda says yes, and his 2020 pilot was designed to test exactly that by holding diet quality and quantity fixed. Everything else is who is being addressed. A woman training hard gets Sims and Panda saying the same thing. Someone with gallbladder history gets Longo. Someone trying to lose fat gets Norton. Someone using fasting therapeutically for symptoms gets Pompa, who asks for a build-up rather than a jump.
All six accept that a shorter, consistent eating window reduces intake for most people and that the reduction itself is the reliable effect. All six are against grazing across the whole day.
Four of them, Panda, Longo, Sims and Norton, explicitly protect the morning meal or the fuelling of hard training; Sinclair does not, and Pompa leaves the placement to your schedule. Nobody in this set disputes that the daily window is easier to sustain than chronic caloric restriction, and nobody argues for training in a prolonged fasted state.
A trial comparing an early window against a late window of identical length, with the same calories, in the same people. Panda said in 2017 that this had not been tested even in animals, and nobody has published it since. That single trial would settle the Sinclair-against-Panda half of the question.
The Norton half needs a timing-against-calories trial with intake genuinely equated and eating times actually measured, which Panda's own review identifies as the thing almost no existing study did. Longo's four-week duration cap would fall to a head-to-head of 16:8 against 12:12 with gallstone incidence and cardiovascular endpoints, and Sims's objection to a trial of 16-hour time-restricted eating in trained women powered for endocrine and performance endpoints.
You do, and your call is dated, kept, and yours to change. Follow the people you already trust and what they publish turns into a short daily practice.
Free to sign up and use. We do not ask for a card.