#220 Less Pancakes, More Bacon? The Ketogenic Diet for Weight Loss

CLINICAL QUESTION

Is the ketogenic diet effective for weight loss?

BOTTOM LINE

At best, ketogenic diets help patients lose ~2 kg more than low-fat diets at one year, but higher quality studies show no difference. Weight loss peaks ~5 months but is generally not sustained. There are no randomized controlled trials (RCTs) on mortality or cardiovascular disease. An individual’s weight change can vary -30 to +10 kg with any diet.

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EVIDENCE

Focusing on most relevant systematic reviews:

Systematic review of 13 RCTs of ketogenic versus low-fat diets, 1,577 participants (61% women, BMI 30-43). At 12-24 months ketogenic diet:¹
- Lost 0.9 kg more than low-fat diet (statistically different).
- Statistically significant but likely clinically meaningless changes in surrogate markers (example LDL 0.12 mmol/L higher).
- Drop-out 13-84% across studies.
Systematic review of 11 RCTs and 1,369 participants (71% women, BMI 30-36) at 6-24 months:²
- Ketogenic-type diet lost 2.2 kg versus low-fat diet, statistically different but results inconsistent.
  - No difference if focus on higher quality studies.
- Surrogate marker changes similar to above.^1,2

Other systematic reviews (5-24 RCTs) confounded by including low-carbohydrate diets that are likely not ketogenic. Results inconsistent: No difference in weight3-5 to 3.6 kg weight loss.^6-8 No systematic reviews or RCTs2 examined mortality or cardiovascular disease. 2018 RCT (609 patients):⁹ Weight loss at one year:

Low-carbohydrate diet (<20 g/day at start) 6.0 kg versus low-fat diet 5.3 kg; not statistically different.
Patient genotypes (favouring one diet type) had no impact on weight loss.
Individual’s weight change varied from -30 to +10 kg in either group.

Context:

Typical Canadian diet: 48% carbohydrate, 32% fat, 17% protein.¹⁰
No standard definition for carbohydrate content in ketogenic diet, but most start with carbohydrate restriction of <20-50 g/day (10% of energy) for ~2 months before slow re-introduction of carbohydrates.^1,11
Weight loss peaks ~5 months, then slow regain.
- Example:¹² From baseline, weight loss 6.5 kg at five months and 4.7 kg at one year.
Tendency for decreased caloric intake on ketogenic diet.^9,12,13
Observational data suggests long-term low-carbohydrate consumption may be associated with increased mortality.¹⁴

September 24, 2018

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Author(s):

Adrienne J Lindblad BSP ACPR PharmD
G. Michael Allan MD CCFP
Rhonda Ting BScPharm

1. Bueno NB, de Melo, IS, de Oliveira SL, et al. Br J Nutr. 2013; 110(7):1178-87.

2. Mansoor N, Vinknes KJ, Veierod MB, et al. Br J Nutr. 2016; 115(3):466-79.

3. Meng Y, Bai H, Wang S, et al. Diabetes Res Clin Pract. 2017; 131:124-31.

4. Hu T, Mills KT, Yao L, et al. Am J Epidemiol. 2012; 126 Suppl 7:44-54.

5. Huntriss R, Campbell M, Bedwell C. Eur J Clin Nutr. 2018; 72(3):311-25.

6. Nordmann AJ, Nordmann A, Briel M, et al. Arch Intern Med. 2006; 166(3)285-93.

7. Sackner-Berstein J, Kanter D, Kaul S. PLoS One. 2015; 10(10):e0139817.

8. Bravata DM, Sanders L, Huang J, et al. JAMA. 2003; 289(14):1837-50.

9. Gardner CD, Trepanowki JF, Del Gobbo LC, et al. JAMA. 2018; 318(7):667-79.

10. Canadian Community Health Survey – Nutrition: Nutrient intakes from food and nutritional supplements. Statistics Canada. 2017-06-20. Available from: https://www150.statcan.gc.ca/n1/daily-quotidien/170620/dq170620b-eng.htm. Last Accessed: September 13, 2018.

11. Moreno B. Crujeiras A, Bellido D, et al. Endocrine. 2016; 54(3):681-90.

12. Shai I, Schwarzfuchs D, Henkin Y, et al. N Engl J Med. 2008; 359(3):229-41.

13. Johnstone AM, Horgan GW, Murison SW, et al. Am J Clin Nutr. 2008; 87(1):44-55.

14. Seidelmann SB, Claggett B, Cheng S, et al. Lancet Public Health. Epub ahead of print August 16, 2018.

Authors do not have any conflicts of interest to declare.