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The low-carb show 4/4

The science

If you look at the science you can easily get hopelessly confused, as you can find studies that pretty much supports anything. Many foods have been described as either good or bad for your health. It is therefore necessary to look at the preponderance of the evidence available instead of ´cherry picking´ some studies. In the field of nutrition, we have lots of epidemiological studies, these studies look for causes and risk factors for diseases in defined populations.

These studies will show you associations between certain behaviours and diseases but cannot give you a direct causal relationship. Studying population-based risk factors for diseases is crucial to testing the hypotheses we get from basic research. This basic research gives us an understanding on how nutrients affect the functioning of our bodies, the mechanism of action.

The hypotheses that we get from these studies should then be tested in clinical trials. The randomized, controlled clinical trial is the standard to demonstrate that some type of intervention works. In these studies, you have 2 groups of people, of which one group changes their diet and the other control group maintains their original diet. This gives the possibility to compare the outcomes of the 2 groups at the end of the study and show the possible effects of the dietary intervention.

There are also studies on centenarian populations from around the world, populations where a bigger than average part of the population lives beyond 100 years old. These studies are very helpful to determine long term safety, efficacy, and compliance of a certain diet. The case with many of the studies that would support a low carbohydrate diet is that they are only based on an epidemiological study or a small clinical trial and are not supported by the whole of the science. If you look at the whole of science, you’ll soon realize that a low carbohydrate diet with high protein and high saturated fat is actually one of the worst diets for your long-term health. There exists no population with record longevity that eats this type of diet. So, what do we know about low carbohydrate diets that are naturally high in proteins and fat?

High protein intake is consistently being associated with ageing and disease, and our protein requirements are quite low. The work of T. Colin Campbell, PhD is probably the most famous research done on the detrimental effects of high protein intake, especially from animal sources (17). A diet with animal protein makes the liver excrete excess amounts of IGF-1, a cancer promoting growth hormone. When we are minors, we need this growth hormone for growth but with adulthood high levels of IGF-1 circulating in the blood are associated with cancer. There is a rare genetic defect which makes the body unable to produce IGF-1, which leads to dwarfism. These people are protected against most types of cancer (18).

Studies on the effects of high fat in your diet have shown that this leads to cardiovascular diseases, as shown in the research done by Caldwell B. Esselsteyn. Jr., MD (19). Low-fat plant-based diets are actually the only diets that have shown to be able to halt and even reverse the progression of coronary artery disease, caused by atherosclerotic plaques that build up in the arteries, and the low-carbohydrate diets impair arterial function.

There are also often flaws in the design of studies that show the proposed benefits of low carbohydrate diets. For example, several studies often cited (20,21), show a low carbohydrate diet to be the best for weight loss compared to low fat diets. These studies describe a low-fat diet as a diet with contains less than 30% of calories from fat. This is not like the low-fat diet used by Caldwell B. Esselsteyn. Jr., MD which showed lots of benefits, these were done with a diet that contained only approximately 10% fat. Dietary fiber intake in the low-fat group is also low, which implies that they were eating lots of unhealthy refined carbohydrates.

The reports of people feeling much better when adopting a low carbohydrate diet are for a large part dependent on their diet before they adopted the new diet. When you leave lots of refined flour and sugars out of your diet, that will make you feel better but does not imply that your diet is healthy.

A new, vegan version of the low-carbohydrate diet, the so-called Eco-Atkins diet, was devised in 2010 (22). They wanted to find out if the negative effects of the low carbohydrate diet were because of the animal-based proteins and fats. They found that a low-carbohydrate diet based on animal sources was associated with higher all-cause mortality, whereas a vegetable based low carbohydrate diet was associated with a lower all-cause mortality and cardiovascular disease mortality rates, compared to a regular diet (23). So, this would imply that it’s more important if your food is animal or plant based, than the ratio of macronutrients in your diet.

The big problem with all these types of low carbohydrate diets is that people do not eat nutrients, they eat food. A low-carbohydrate diet is very restrictive and difficult to maintain, as our bodies are designed to crave carbohydrates and an extra serving of healthy vegetables might already push you over the carbohydrate limit of these types of diets. There is only so much oil or fat you can take, with ketogenic diets it’s always a case of finding a balance between nausea and ketosis.

Oils consisting out of medium chain triglycerides (MCT oils) like for example coconut oil, are more ketogenic than regular long chain triglyceride oils because they generate more ketones per calorie when metabolised. These MCT oils allow for a lower proportion of fat in the diet and thus more carbohydrates and protein. A diet consisting for 45% out of these oils is seen as a balance between ketosis and minimising gastrointestinal complaints.

So, you might lose a little bit of extra weight in the long run, although 1 kilo in one year is not going to make the difference, but you’ll pay for it with your overall health (24). A low carbohydrate diet won’t support good bone health, a healthy brain, heart and gut microbiome, and it will lead to plaque build-up in the arteries (25).

References:

  1.  Good calories, bad calories. Gary Taubes 2008
  2. Calorie for calorie, dietary fat restriction results in more body fat loss than   carbohydrate restriction in people with obesity. D. Hall, Bemis Cell metabolism, September 2015
  3. Energy expenditure and body composition changes after an isocaloric ketogenic   diet in overweight and obese men. D Hall, Y Chen The American Journal of Clinical Nutrition. Volume 104, issue 2, July 2016
  4. Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. S Johnston, L Tjonn The American Journal of Clinical Nutrition. Volume 83, issue 5, May 2006
  5. Ketogenic diets for drug‐resistant epilepsy. Kirsty J Martin-McGill  Cochrane database for systematic reviews 2018
  6. Hypercarnivory and the brain: protein requirements of cats reconsidered. Eisert R. Journal of Comparative Physiology, January 2011
  7.  “Fishing” for the origins of the “Eskimos and heart disease” story. Facts or wishful thinking? A review George J. Fodor, MD Canadian Journal of Cardiology April 2014
  8. Studies on the metabolism of Eskimos. Heinbecker J. Journal Biol Chem 80 1928
  9. A Selective Sweep on a Deleterious Mutation in CPT1A in Arctic Populations  F.J. Clemente. American Journal of Human genetics 95. November 2014
  10. Bone mineral content of North Alaskan Eskimos. Richard B. Mazess, PhD The American Journal of Clinical Nutrition, Volume 27, Issue 9, September 1974
  11. Overweight and diabetes prevention: is a low-carbohydrate–high-fat diet recommendable? Brouns European Journal of Nutrition, March 2018
  12. Popular diets: correlation to health, nutrition, and obesity. Kennedy, Bowman Sa Journal of the Academy of Nutrition and Dietetics. Volume 101, Issue 4, April 2001
  13. Pregnancy Ketonemia and Development of the Fetal Central Nervous System. Agata Bronisz International Journal of Endocrinology Volume 2018, Article ID 1242901
  14. Glucose metabolism in the developing brain. Vannucci RC, Vannucci SJ Seminars in Perinatology, Volume 24, Issue 2, April 2000
  15. High-Fat Diet Induces Dysbiosis of Gastric Microbiota Prior to Gut Microbiota in Association With Metabolic Disorders in Mice. He Cheng Frontiers in microbiology April 2018
  16. Effects of dietary fat on gut microbiota and faecal metabolites, and their relationship with cardiometabolic risk factors: a 6-month randomised controlled-feeding trial. Wan Wang. BMJ Journals Gut, February 2019
  17. The China study. T. Colin Campbell, PhD 2016
  18. Congenital IGF1 deficiency tends to confer protection against post-natal development of malignancies. R Steuerman European journal of Endocrinology April 2011
  19. Prevent and reverse heart disease, Caldwell B. Esselsteyn Jr. M.D. 2007
  20. Effects of Low-Carbohydrate diets versus low-fat diets on metabolic risk factors: A meta-analysis of randomized controlled clinical trials. Tian Hu, Katherine T.Mills Lu Yao American journal of epidemiology, volume 176 issue 7 October 2012
  21. Long-term effects of a very low-carbohydrate weight loss diet compared with an  isocaloric low fat diet after 12 months. Grant D Brinkworth. American journal of clinical nutrition, volume 90 issue 1 July 2009
  22. Effect of a 6-month vegan low-carbohydrate (‘Eco-Atkins’) diet on cardiovascular risk factors and body weight in hyperlipidaemic adults: a randomised controlled trial.  David J A Jenkins BMJ journals, Volume 4 issue 2 February 2010
  23. Low-carbohydrate diets and all-cause and cause-specific mortality: Two cohort Studies. T. Fung Annals of internal medicine, September 2010
  24.  Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Nassib Bezerra Bueno British Journal of Nutrition, May 2013
  25. Low-carb diets 'are unsafe and should be avoided'. Ana Sandoiu, August 2018 MedicalNewsToday.com     https://www.medicalnewstoday.com/articles/322881.php

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