When it comes to losing weight, everyone has an opinion. From low-carb to low-fat, and everything in between, there is no shortage of diets that cater to every preference and taste. But which (if any) of these diets are truly effective at achieving and maintaining long-term, sustainable weight loss?
In today’s post, we’re taking a critical, evidence-based look at the diets of our time to find out which approaches are worth a second glance.
When it comes to weight loss, it’s important to remember that the “best” diet can vary from person to person, depending on individual health, lifestyle, and preferences. However, there are several diets that have been supported by scientific evidence for their effectiveness in weight loss. Below, we cover the most notable ones.
The Ketogenic Diet
A keto (short for ketogenic) diet is a low-carb, high-fat diet that restricts carbohydrate intake to 20-50 g of net carbs (total carbohydrates minus fibre) per day, or 5-10% of total energy (1). While targets for protein and fat vary based on the level of “strictness”, these macronutrients typically provide 20-25% and 65-80% of total energy, respectively.
Weight loss is theorized to occur on a ketogenic diet via several mechanisms: lower body fat stores resulting from less circulating insulin; increased satiety; and a greater production of glucose from protein (which uses a lot of extra energy; 2). Additionally, there is often a reduction in total calorie intake on a keto diet.
When compared to a low-fat diet, a ketogenic diet may result in marginally greater weight loss at the 12-month mark (0.9 kg difference), while improving some risk factors for cardiovascular disease (triglycerides and HDL cholesterol) and potentially worsening others (LDL cholesterol; 3).
Low-Carb Diets
As the name implies, low-carb diets (Atkins, South Beach, the Zone) restrict carbohydrates, similar to the ketogenic diet but not to the point of inducing ketosis.
While the “allowable” intake of carbohydrates varies by diet, most advise an intake of < 40% of total calories.
A 2014 meta-analysis and systematic review (4) found that compared to no dietary intervention, a low-carb diet resulted in a weight loss of 8.73 kg at 6 months and 7.25 kg at 12 months. This rate of weight loss was comparable to a low-fat diet, where total carbohydrate and fat intake equalled 60% and < 20%, respectively (4).
Plant-Based Diets
Including vegetarian and vegan diets, these focus on foods primarily from plants. They are effective for weight loss and also provide numerous health benefits. Plant-based diets are typically lower in calories and fat, which can help in weight management.
The number of people following a plant-based eating diet jumped by a whopping 600% between 2014 and 2017 (5), thanks in part to popular documentaries and food companies investing in plant-based alternatives like Beyond Meat. In addition, recent guidelines, including both Canada’s Food Guide and the EAT-Lancet report emphasize the importance of plant-based diets to meet global health and environmental initiatives. But can a plant-based diet change an individual’s body weight?
Observational data from the Adventist Health Studies have found that an individual’s body weight increases with the intake of animal foods (i.e. vegans weigh less than vegetarians, who weigh less than pescatarians, who weigh less than omnivores; 6) and data from the EPIC-Oxford trial suggests that vegans have significantly lower rates of age-related weight gain compared to omnivores (7). In a meta-analysis of 15 interventional trials, individuals who followed a plant-based diet (without energy restrictions) for a minimum of 4 weeks lost on average 4.6 kg (8). However, given the short duration of follow-up, it is unknown if these weight changes were sustained long-term.
Intermittent Fasting
As discussed in a previous post, intermittent fasting, which typically restricts the eating window to just 6-8 hours per day, is as effective as calorie-restricted diets in achieving weight loss that is maintained at 12-months follow-up (9). In addition, fasting may lead to better insulin control versus calorie-restricted diets, without any additional adverse outcomes (9).
The Bottom Line
So, if weight loss is your goal, which of the above diets should you follow – low carb, keto, vegan, low-fat, or intermittent fasting?
Based on the evidence available to date, it appears that any diet can work, provided you are able to stick with it long-term. So, in short, whichever diet works best for you and your lifestyle is best!
In North America, obesity is considered a progressive chronic disease that requires effective, long-lasting interventions to mange. Diets that are too restrictive or have a set end date are unlikely to provide long-lasting results and in fact, can do more harm than good.
How Can Cronometer Help You Lose Weight?
If you’re looking to Cronometer for help losing weight, we’re more than happy to help! Tracking your food intake, and more specifically using a mobile app to track your food intake has been proven to help people lose weight (10, 11, 12, 13).
Using Cronometer can increase awareness and accountability, provide you with real-time feedback and increase your education surrounding nutrition, resulting in proven weight-loss results.
Check out this blog for a beginner’s guide to losing weight with Cronometer or these 9 tips for achieving long term weight loss.
If you’re following the ketogenic diet, check out this blog for some guidance on how to leverage all of our keto settings.
Cronometer Gold subscribers can also take advantage of our Intermittent Fasting Timer to time, track and chart your fasts so you can better assess the impact of all your hard work.
References
1. Royall D. Diet Composition: Keto Diets. PEN: Practice-based evidence in Nutrition. 2018 Nov. Access through subscription only: https://www.pennutrition.com/KnowledgePathway.aspx?kpid=25499&trcatid=38&trid=27298
2. Paoli A, Rubini A, Volek JS, Grimaldi KA. Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. Eur J Clin Nutr. 2013 Aug;67(8):789-96. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/23801097
3. Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr. 2013 Oct;110(7):1178-87. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/23651522
4. Johnston BC, Kanters S, Bandayrel K, Wu P, Naji F, Siemieniuk RA, et al. Comparison of weight loss among named diet programs in overweight and obese adults: a meta-analysis. JAMA. 2014 Sep 3;312(9):923-33. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/25182101
5. Forgrieve J. The Growing Acceptance of Veganism. Forbes. 2018 Nov. Available from: https://www.forbes.com/sites/janetforgrieve/2018/11/02/picturing-a-kindler-gentler-world-vegan-month/#7412046b2f2b
6. Tonstad S, Stewart K, Oda K, Batech M, Herring RP, Fraser GE. Vegetarian diets and incidence of diabetes in the Adventist Health Study-2. Nutr Metab Cardiovasc Dis. 2013 Apr;23(4):292-9. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/21983060
7. Rosell M, Appleby P, Spencer E, Key T. Weight gain over 5 years in 21,966 meat-eating, fish-eating, vegetarian, and vegan men and women in EPIC-Oxford. Int J Obes (Lond). 2006 Sep;30(9):1389-96. Epub 2006 Mar 14. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/16534521
8. Barnard ND, Levin SM, Yokoyama Y. A systematic review and meta-analysis of changes in body weight in clinical trials of vegetarian diets. J Acad Nutr Diet. 2015 Jun;115(6):954-69. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/25620754
9. Harris L, Hamilton S, Azevedo LB, Olajide J, De Brún C, Waller G, et al. Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. JBI Database System Rev Implement Rep. 2018 Feb;16(2):507-547. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/29419624
10. Burke, L. E., et al. (2011). “Self-monitoring in weight loss: a systematic review of the literature.” Published in the Journal of the American Dietetic Association.
11. Laing, B. Y., et al. (2014). “Effectiveness of a smartphone application for weight loss compared with usual care in overweight primary care patients: a randomized, controlled trial.” Published in Annals of Internal Medicine.
12. Carter, M. C., et al. (2013). “Adherence to a smartphone application for weight loss compared to website and paper diary: pilot randomized controlled trial.” Published in the Journal of Medical Internet Research.
13. Tang, J., Abraham, C., Greaves, C., & Yates, T. (2014). “Self-directed interventions to promote weight loss: a systematic review of reviews.” Published in the Journal of Medical Internet Research.
