Caloric Restriction

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title: Caloric Restriction slug: caloric-restriction category: nutrition summary: Sustained reduction in calorie intake without malnutrition — the most replicated lifespan-extending intervention across species, with measurable healthspan effects in humans (CALERIE trial). lastUpdated: 2026-05-17 tags: [caloric restriction, CALERIE, lifespan, dietary restriction] references:

• "Kraus, W. E. et al. 2 years of calorie restriction and cardiometabolic risk (CALERIE): exploratory outcomes of a multicentre, phase 2, randomised controlled trial. Lancet Diabetes Endocrinol. 7, 673–683 (2019)."

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What it is

Caloric restriction (CR) is sustained reduction in energy intake — typically 15–25% below ad libitum — while maintaining nutrient adequacy. It is distinct from outright undernutrition or malnutrition.

Why it matters

CR is the most robust lifespan-extending intervention in laboratory model organisms (yeast, worms, flies, mice, rats) and produces healthspan benefits in non-human primates (Wisconsin and NIA studies). In humans the CALERIE trial randomised non-obese adults to ~14% CR for 2 years and showed:

• improvements in cardiometabolic risk factors (LDL, blood pressure, insulin sensitivity);
• modest reduction in epigenetic-age acceleration;
• no detrimental effect on quality of life;
• some loss of lean mass — relevant to older adults.

Mechanisms

CR acts on the nutrient-sensing axis: reduced mTORC1 signalling, AMPK activation, lower IGF-1, increased autophagy.

Practical considerations

Long-term CR is hard to sustain. Many practical interventions — intermittent fasting, time-restricted eating, Mediterranean- style diets — capture some of the same mechanisms with better adherence.

For older adults, the risk of unintentional weight and lean-mass loss outweighs the expected benefit of CR; protein adequacy and resistance training become more important.

Related entries

See also: Intermittent fasting, Protein and mTOR, Deregulated nutrient-sensing.