Is a low-carbohydrate (aka ketogenic) diet, the right diet for you?

The ketogenic diet was first introduced as a treatment for epilepsy. One theory of why this diet is effective in treating epilepsy is that it changes energy metabolism in the brain. The brain solely uses glucose as its source of energy; it is the most energy-demanding of all organs using 20% of glucose-derived energy.

So why am I telling you this? Well, this diet has become increasingly popular for weight-loss. I constantly see on the internet supplements/shakes/regimes for people to adopt this diet without knowing much of what a keto diet is, and how this may affect you in the short and long term.

After a few days of an extremely low carbohydrate diet, your glucose reserves become insufficient as an energy source for your body; this triggers the release of ketone bodies by the liver.

The evidence

There have been a number of animal and human studies to assess the effects of this diet on weight, type 2 diabetes and cardiovascular disease. One animal study showed that when fed a keto diet, more weight-loss overall was observed compared to a typical western diet, however, the keto diet also showed that lean mass was lost as well as fat mass. Another study in type 2 diabetics showed no difference in weight-loss between a low carb, high unsaturated fat diet and a high carb, low-fat diet, and at 52 weeks the low carb group regained more weight than the other diet group.

Studies have also investigated the effects a ketogenic diet has on blood glucose levels in those diagnosed with type 2 diabetes. One study did show better insulin sensitivity at six months when consuming a ketogenic diet, but after one year this was no longer the case.

The evidence is mixed for supporting the benefits of a ketogenic diet outside of the treatment for epilepsy. It seems there are benefits short term for weight-loss and insulin sensitivity but not long-term, and at what cost? What effect does this diet have on the brain and ultimately psychological aspects?

One study indicated psychological well-being improved when on a low carbohydrate diet in the initial two weeks. However, the participants' mood returned to the same level as when they started the study when observed in the following weeks and months. Again, when comparing two diets of a high carb low-fat diet and a low carb high-fat diet it was shown that those on the high carb low-fat diet had better improvements after one year in anxiety, depression and confusion/bewilderment among other psychological areas. 

The role of carbohydrates for your brain

Carbohydrates are the main source for providing you with energy, and this helps you to move around and think clearly for completing your daily tasks. Carbohydrates include rice, bread, pasta and potatoes, among others, and these break down into glucose and are distributed around the body. When glucose is used by the brain, this ensures proper brain function by maintaining neurons and generating neurotransmitters between the neurons. If glucose metabolism is impaired within the brain, this can cause psychological distress and if continued may become an underlying factor for several diseases.

Should you choose a low carbohydrate/ketogenic diet?

Ultimately this decision is up to you. Very low carbohydrate diets are hard to stick to in the long term, and this may encourage yo-yo dieting - which you want to avoid.

In my professional opinion, I would recommend looking into other avenues for weight-loss, with support from your nutritionist. But if you have carefully considered a ketogenic diet and you feel that it is something you wish to start, I would do so with caution and under the advice of your nutritionist or dietician. Keep in mind there are different types of ketogenic diets, although all are based on very low carbohydrates; there are more healthful ketogenic diets out there which may give beneficial effects. 

References

• Brinkworth G.D., Buckley J.D., Noakes M., Clifton P.M., Wilson C.J. (2009) Long-term effects of a very low-carbohydrate diet and a low-fat diet on mood and cognitive function. Archives of International Medicine. 169 (20): 1873-80. Available from: https://www.ncbi.nlm.nih.gov/pubmed/19901139
• Foster G.D., Wyatt H.R., Hill J.O., McGuckin B.G., Brill C., Mohammed B.S., Szapary P.O., Rader D.J., Edman J.S., Klein S. (2003) A Randomized Trial of a Low-Carbohydrate Diet for Obesity. The New England Journal of Medicine. 348 (21): 2082–90. Available from: https://www.nejm.org/doi/10.1056/NEJMoa022207?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dwww.ncbi.nlm.nih.gov
• Garbow J.R., Doherty J.M., Schugar R.C., Travers S., Weber M.L., Wentz A.E., Ezenwajiaku N., Cotter D.G., Brunt E.M., Crawford P.A. (2011) Hepatic steatosis, inflammation, and ER stress in mice maintained long term on a very low-carbohydrate ketogenic diet. American Journal of Physiology. Gastrointestinal and Liver Physiology. 300 (6): G956–67. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3119109/
• Mergenthaler, P., Lindauer, U., Dienel, G. and Meisel, A. (2013). Sugar for the brain: the role of glucose in physiological and pathological brain function. Trends in Neurosciences. 36 (10), 587-597. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900881/
• Owen O.E., Morgan A.P., Kemp H.G., Sullivan J.M., Herrera M.G., Cahill G.F (1967) Brain metabolism during fasting. The Journal of Clinical Investigation. 46 (10): 1589–95. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC292907/
  Rosen J.C., Gross J., Loew D., Sims E.A. (1985) Mood and appetite during minimal-carbohydrate and carbohydrate-supplemented hypocaloric diets. The American Journal of Clinical Nutrition. 42 (3):371–79. Available from: https://www.ncbi.nlm.nih.gov/pubmed/4036844
• Tay J., Luscombe-Marsh N.D., Thompson C.H., Noakes M., Buckley J.D., Wittert G.A., Yancy W.S., Brinkworth G.D. (2015). Comparison of low- and high-carbohydrate diets for type 2 diabetes management: A randomized trial. The American Journal of Clinical Nutrition. 102 (4):780–790. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26224300
  Wheless, J. (2008). History of the ketogenic diet. Epilepsia. [online] 8:3-5. Available from: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1528-1167.2008.01821.x