Intermittent Fasting: The Canadian Evidence-Based Guide

Intermittent fasting (IF) has been one of the most studied eating patterns of the last decade. When the dust settles, the best summary is: IF works as well as regular calorie restriction for weight loss, and modestly better for insulin sensitivity. It is not inherently magical.

The three mainstream protocols

16:8 — eat in an 8-hour window, fast for 16. Most sustainable.

5:2 — eat normally 5 days a week; two non-consecutive days with ~500–600 kcal.

Alternate-day fasting — harder to sustain for most people.

What research shows

Meta-analyses find weight loss roughly equivalent to calorie restriction. Insulin sensitivity improvements are modest but consistent. Long-term adherence is the main challenge — many people regain after 12 months.

Who should skip IF

People with a history of eating disorders, pregnant or breastfeeding women, anyone on insulin or sulfonylureas (risk of hypoglycaemia).

The bottom line

If it fits your life, IF is a reasonable tool. If it makes you miserable, skip it — traditional calorie awareness works just as well.

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