Intermittent fasting: what studies show

01The short answer

02What are we talking about?

Intermittent fasting covers several ways of alternating periods when you eat and periods when you eat nothing, or very little: eating within a time window each day, or cutting back sharply on certain days of the week. In every case the idea is the same: eating less, by choosing when.

03What Obesity Canada concludes

In the nutrition chapter of its guidelines (2022), Obesity Canada compares the two approaches: intermittent and continuous calorie restriction achieved similar short-term weight reduction. Its guidelines list intermittent fasting among several possible options, noting that there is no one-size-fits-all eating pattern and that advice should be personalized.

04The 2026 Cochrane review

In February 2026, Cochrane published a review of 22 clinical trials involving 1,995 adults. Intermittent fasting did not show a clinically meaningful effect on weight loss compared with standard dietary advice or no intervention.

The authors point out that the evidence is limited and that few trials followed people over the long term. In other words, nothing shows that intermittent fasting does better than other approaches; if a meal schedule helps you eat less, it is one option among others, not a shortcut. Eating to lose weight covers the basics shared by every approach.

05Who it is not suitable for

Dietitians Australia, the Australian professional body for nutrition and dietetics, is clear about several cases:

• Pregnancy and breastfeeding: intermittent fasting is not suitable.
• Eating disorders: for someone vulnerable, it could be a dangerous trigger.
• Diabetes or cancer: seek medical advice on whether it is appropriate for you; if you take diabetes medication, do not try it without talking to your doctor first.

With any other health problem or medication, talk to your doctor too; a registered dietitian can tell you whether this way of eating suits you.

06Fasting and a noon class

A noon class fits into a working day; how to place your meals around it, and where a fast fits if there is one, is something to decide with a registered dietitian, not by following a trend. On the activity side, Obesity Canada recommends aiming for 150 minutes or more of aerobic activity a week, and notes that strength training may help maintain weight.

Joanie Roussy's women's classes, at noon on weekdays on Nuns' Island, count toward those minutes; adult karate, which is mixed, is held in the evening, from age 14.

07At noon, from downtown

From downtown, the REM links Gare Centrale to Île-des-Sœurs station; it has been running since July 31, 2023. The dojo is at 550 chemin du Golf, suite 010: the getting to the dojo page works out the route by the mode you choose, and the schedule shows the class days.

Sources

1. Obesity Canada, guidelines, chapter “Medical Nutrition Therapy in Obesity Management” (2022) — obesitycanada.ca/wp-content/uploads/2022/10/Medical-Nutrition-Therapy_22_FINAL.pdf
2. Cochrane, “Evidence behind intermittent fasting for weight loss fails to match hype” (2026) — www.cochrane.org/about-us/news/evidence-behind-intermittent-fasting-weight-loss-fails-match-hype
3. Dietitians Australia, “Intermittent fasting” (2022) — dietitiansaustralia.org.au/print/pdf/node/419
4. Obesity Canada, chapter “Physical Activity in Obesity Management” (2020) — obesitycanada.ca/wp-content/uploads/2020/08/Physical-Activity-in-Obesity-Management.pdf

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