Tools for Practice Outils pour la pratique

#247 Fact or Fad: Intermittent fasting for sustained weight loss

Does intermittent fasting result in greater sustained (>6 month) weight loss than continuous dieting in adults?

Although inconsistently defined, intermittent fasting (example 500 kcal/day for 2 days/week) and continuous dieting (~25% reduction in caloric intake daily) result in similar weight loss, usually ~5-9kg at 6 months-1 year. Discontinuation rates with both diets is up to ~60%.

CFPCLearn Logo

Reading Tools for Practice Article can earn you MainPro+ Credits

La lecture d'articles d'outils de pratique peut vous permettre de gagner des crédits MainPro+

Join Now S’inscrire maintenant

Already a CFPCLearn Member? Log in

Déjà abonné à CMFCApprendre? Ouvrir une session

“Fasting” generally refers to reducing caloric intake by ~75% of caloric needs/day; “continuous dieting” generally refers to reducing caloric intake by ~25%/day.  Systematic review of 9 randomized, controlled trials (RCTs) at least 6 months in duration, 981 patients.1 Example regimen: fasting 2 days/week interspersed with 5 days/week regular intake. After 6 months-2 years: 
  • No difference in mean weight loss. 
  • Mean weight loss range in both groups: 2.1-26.6 kg. 
6 RCTs published since above review, 24 to 332 patients, randomized to intermittent fasting (alternate day fasting, 2 days fasting with 5 non-fasting days/week, or weekly fasting) versus continuous dieting and/or no intervention control: 
  • 5/6 RCTs: mean weight loss ranged ~5-9 kg in both arms, not statistically different.2-6 
    • Best quality RCT, 100 patients, randomized to alternate-day fasting, continuous dieting, or no intervention control for 6 months.2 After additional 6-month follow-up: 
      • Weight loss between fasting and continuous dieting: no difference. 
        • Both diets lost ~6% more than no intervention. 
    • 1 RCT, 51 men, both groups decreased calories by 33%. Intermittent fasting (alternating 2-week blocks of fasting with regular diet) or continuous diet for 16 weeks.7 After 6-month follow-up: 
      • Statistically significant difference in weight loss: 11 kg versus 3 kg (continuous). 
      • Only patients who completed the study were included in the analysis. 
  • Discontinuation rates 30-60%.1,3,4 
  • Weight loss for most diets peaks ~ 6 months,1 then slow regain.3,6,7 
  • No weight loss diet appears superior to another across populations, however individual results vary widely.8 
  • Mediterranean diet is the only diet that reduces cardiovascular disease.9 

Latest Tools for Practice
Derniers outils pour la pratique

#369 Remind me, do medications that target brain amyloid improve my dementia?

Are amyloid-targeting monoclonal antibodies safe and effective for mild cognitive impairment or Alzheimer’s dementia?
Read Lire 0.25 credits available Crédits disponibles

#368 Sodium Restriction in Heart Failure: Beneficial or pouring salt in the wound?

Does sodium restriction improve outcomes in patients with chronic heart failure?
Read Lire 0.25 credits available Crédits disponibles

#367 Oral Calcitonin Gene-related Peptide Antagonists: A painfully long name for the acute treatment of migraines

What are the risks and benefits of ubrogepant for the acute treatment of episodic migraines?
Read Lire 0.25 credits available Crédits disponibles

This content is certified for MainPro+ Credits, log in to access

Ce contenu est certifié pour les crédits MainPro+, Ouvrir une session

  • Natalie Holden BSc BScPharm
  • Jessica Kirkwood MD CCFP
  • Adrienne J Lindblad BSP ACPR PharmD

1. Headland M, Clifton P, Carter S, et al. Nutrients. 2016; 8(324):1-12.

2. Trepanowski JF, Kroeger CM, Barnosky A, et al. JAMA Intern Med. 2017; 177(7):930-8.

3. Headland M, Clifton P, Keogh J. Int J Obes. 2018 Nov 23 (epub ahead of print).

4. Carter S, Clifton PM, Keough JB. JAMA Netw Open. 2018; 1(3):1-12.

5. Conley M, Le Fevre L, Haywood C, et al. Nutr Diet. 2018; 75:65.

6. Sundfǿr TM, Svendsen M, Tonstad S. Nutr Metab Cardiovasc Dis. 2018; 28:698-706.

7. Byrne NM, Sainsbury A, King NA, et al. Int J Obes. 2018; 42:129-138.

8. Ting R, Dugre N, Allan GM, et al. Can Fam Physician. 2018; 74(12):906.

9. Allan GM, Sharma AM, Lindblad AJ. Tools for Practice #46 online publication. Published April 16, 2015. Available at: Accessed Sept 17, 2019.

Authors do not have any conflicts of interest to declare.

Les auteurs n’ont aucun conflit d’intérêts à déclarer.