Time-Restricted Eating

What it is

Time-restricted eating (TRE) confines food intake to a daily eating window, typically 6–10 hours, leaving a fasting window of 14–18 hours. Earlier- in-the-day TRE (e.g. 8 am – 4 pm) tends to show stronger metabolic effects than late TRE in human studies.

Why it matters

In rodents, restricting eating to the active phase improves cardiometabolic outcomes even without weight loss. Human data are encouraging but smaller:

• Improvements in insulin sensitivity and blood pressure when matched for calories.
• Weight loss roughly equivalent to continuous calorie restriction; not obviously superior.
• Some 2024 observational data raised concerns about 8-hour TRE and cardiovascular mortality; not yet replicated in RCTs.

Mechanisms

• Aligns eating with the circadian programme of insulin sensitivity and digestive enzyme expression.
• Extends the fasting window, raising autophagy and lowering mTORC1 tone (Disabled macroautophagy).
• May influence the gut microbiome through changes in eating-timing cycles.

Practical points

• Adherence and total calorie intake usually matter more than the precise window.
• TRE is not a license to ignore food quality.
• For older adults, very short windows may make adequate protein intake (see Protein and mTOR) harder to hit.

Related entries

See also: Intermittent fasting, Caloric restriction.