Keto is great right now, but what about long term?
With all the research we have on the short term effects of keto, the general consensus supported by research on the diet’s effects are:
1. Improved control of blood sugar, especially for diabetics.
2. Support of brain function with the hypothesis that it can continue to support brain function with age.2
3. Maintenance of muscle mass in a caloric surplus.3
4. Inability to support muscle mass at maintenance calories/caloric deficit.3
5. Inability to consistently support high intensity exercise.4
Enhanced fat utilization.
6. Improvement in cholesterol levels, decrease in triglycerides and reduction of body fat in the Obese over 24 weeks.
Keep in mind the results of the obese in weight management studies are not typical in every population.
However, despite the abundance of research and anecdotal evidence on what the ketogenic diet can do for you right now, the question remains: what effects does following this dietary practice long term have on the body? It will still be a few more years before we can have a longitudinal study (a study that observes individuals over the course of years or decades) showing the effects of true long term keto use. To date most studies (even the ones listed as ‘long term’, like the Obesity study for example (6)) only measure the effects of the keto diet after 16-24 weeks.
While there are clearly advantages to blood sugar control, nervous system health and the blood lipid profile while on the keto diet, we must also look at what could pose an issue years down the road. According to the Cochrane Colorectal Cancer Group, Colon Cancer is the 2nd most cause of cancer deaths in the Western World. This is largely believed to be a result of our high intake of slow digesting meats (red meat), processed meat and lack of dietary fiber due to processed carbohydrates7. A common issue many people in the fitness community have with novice Keto dieters is an inability to include adequate fiber in their diet to get the higher rates of meat consumption to pass through their digestive system.
The closest thing we have to a longitudinal study (a true long term study) on low carbohydrate intake is a study of 15,000 people in the U.S. that began in the late 1980’s with older participants (45-65) that continued for 25 years through the mortality of over 6,000 of the participants.8 What was determined was that the healthiest diets (lowest mortality rate) were below the recommended +55% carbohydrate diet recommended by the government (keeping in mind the poor carbohydrate choices in the Western diet and the lack of calorie control in the study). The researchers also determined that replacing carbohydrates with animal fats and proteins increases your chance of death versus replacing those carbohydrates with protein and fats from plant sources.
While this study does give a lot of credit to the vegan diet (as many other studies do) you must keep in mind that the population was older plus calories and training goals were not taken into account. The take home message here should be ‘everything in moderation’. Cycle your low carb, animal meat based plans in to improve body composition while incorporating periods for a balanced diet for overall health and supporting muscle mass. As you age look to replace your carbohydrates (to support neurological function and body composition) with plant based sources to (to improve mortality rates and overall health); all in all, the keto diet may be great right now, but don’t make it your long term solution.
1. William S. Yancy, et al. A low-carbohydrate, ketogenic diet to treat type 2 diabetes. Nutrition & Metabolism (Lond). 2005; 2: 34
2. Youngson NA, et al. The mechanisms mediating the antiepileptic effects of the ketogenic diet, and potential opportunities for improvement with metabolism-altering drugs. Seizure. 2017;52:15–9.
3. Salvador Vargas, et al. Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial. Journal of the International Society of Sports Nutrition 2018 15:31
4. Chang CK et al. Low-carbohydrate-high-fat diet: can it help exercise performance? Journal of Human Kinetics. 2017 Feb; 56: 81–92
5. Bueno NB et al. Very-low-carbohydrate ketogenic diet v. Low-fat diet for long-term weight loss: a meta-analysis of randomized controlled trials. British Journal of Nutrition. 2013;110:1178–87
6. Hussein Dashti, et al. Long-term effects of a ketogenic diet in obese patients. Experimental and Clinical Cardiology. 2004 Fall; 9(3): 200–205.
7. Andrew Kunzmann, et al. Dietary fiber intake and risk of colorectal cancer and incident and recurrent adenoma in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. American Journal of Clinical Nutrition. 2015 Oct; 102(4): 881–890
8. Sara Seidelmann, et al. Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. The Lancet Public Health, online August 16, 2018.
