This is the page where Vida tells you what the research supports, including the parts that don’t flatter fasting. You should be able to find that somewhere, and most apps don’t offer it.
What holds up?
Time-restricted eating works for a lot of people as a way of eating less without counting anything. In a review pooling thirteen randomized trials in women, it improved body weight and fasting insulin, with side effects that were minor and resolved on their own.5
In adults with type 2 diabetes, a six-month trial found an eight-hour window produced meaningful weight loss without calorie counting, and both that and ordinary daily restriction lowered long-term blood sugar compared with control.7
In adults with metabolic syndrome, adding a personalized eight to ten hour window to standard care produced a small additional improvement in blood sugar control over three months, with no major adverse events.6
And it holds up on tolerability. Across fifteen randomized trials, people fasting were no more likely to drop out than controls, with similar rates of fatigue and headache.8
What doesn’t?
The idea that the clock itself does something extra, beyond helping you eat less.
In a twelve-week trial comparing a midday-to-evening window against consistent meal timing, there was no statistically significant difference in weight between the groups.3
In a twelve-month trial where everyone was already eating less, adding an eating window on top produced a difference that wasn’t statistically significant.4
Reviewing twenty-two randomized trials, a 2026 Cochrane review concluded that intermittent fasting may make little to no difference in weight loss compared with regular dietary advice, at low certainty.1
Once calories were matched, the window added little.
Is that the whole picture?
No, and it would be misleading to quote only one side. A 2025 umbrella review of meta-analyses graded the evidence for time-restricted eating on weight, fat mass, insulin and long-term blood sugar as high certainty in adults with overweight or obesity.2
Two serious reviews reaching different verdicts is what a live question looks like.
And compared with ordinary daily restriction, eleven randomized trials found broadly comparable results. Which is the fairest summary available: fasting is about as good as the alternatives, and for many people it’s easier to stick to.9
What are the gaps that matter here?
- Nobody has tested varying a fast by cycle phase. The physiology is documented. The protocol hasn’t been trialed.
- Perimenopausal women are barely represented. The trial that measured sex hormones on a narrow window excluded them.
- Most trials run weeks to months. Long-term evidence in women is thin.
- Women at a healthy weight are much less studied than women with overweight or obesity.10