Low Carb: Fact or Fad?

If you have picked up a fitness magazine, newspaper, or even surfed the web in the last 10 years you have undoubtedly come across the topic of” low carb diets”.  Often these diets are associated with some organization based diet such as “The Atkins Diet” or “The Zone Diet”.  What intrigues me about this topic is two-fold. The first being the idea of macro-nutrient ratios in a diet and the second being the quality of those macronutrients. Generally, I would declare myself “macro-nutrient agnostic”, meaning that I do not believe there is a magic ratio of proteins/carbs/fat that we ought to adhere to for optimal health.  I generally take the stand that food quality is “King” in the battle of food vs. health.  That being said I do find the idea of low-carb diets worthy of investigation and believe they can be extremely powerful tools in reversing disease, weight loss, and even in performance.

This week’s post is going give a brief introduction into the effects of low-carb diets on disease and next week’s will focus on weight loss. Over the course of the next month or so I will dive deeper into those categories and explain the mechanisms of action.  For now, we will keep it simple, superficial, and straightforward, much like a first date (minus the expensive tab at the end of the night).

Low-Carb and Disease

Before we begin the discussion of low-carb diets and disease I must make a clarification. There is a difference between low-carb (LC) and low-carb ketogenic (LCKG) diets. In the LC diet, one restricts their carbohydrate intake yet does not cause the body to enter ketosis, a state where your body produces a large amount of ketones to use for fuel instead of glucose molecules (more reading on ketosis can be found here).

Often diets high in carbohydrates are linked to modern, lifestyle based diseases such as type 2 diabetes (T2DM), CVD, and non-alcoholic fatty liver disease (NAFD). In fact, I am of the belief that the large intake of processed, refined carbohydrates, along with sedentary lifestyles is and underlying cause of virtually all of these types of diseases. If that is the case, what effects do low—carb diets have on these diseases?

A 2005 study showed that in a group of obese patients with type 2 diabetes, a low-carbohydrate diet followed for 2 weeks resulted in spontaneous reduction in energy intake to a level appropriate to their height; weight loss that was completely accounted for by reduced caloric intake; much improved 24-hour blood glucose profiles, insulin sensitivity, and hemoglobin A1c; and decreased plasma triglyceride and cholesterol levels (1).  This finding indicated LC diets were successful in weight loss and improving T2DM.

But what about LC diets that don’t result in weight loss? Virtually all the literature indicates that LC diets improve the physiological markers associated with T2DM (2). In fact, using low carbohydrate interventions is effective for improving and reversing type 2 diabetes, and LC diets are now the recommended form of treatment for T2DM (3,4).

LC diets have also been shown to improve the risk of atherogenic dyslipidemia, a key component in CVD (5). This study, although unpublished at this point in time, showed a substantial decrease in TNF-alpha, IL-6, I-CAM, and PAI-1, all indicators of CVD.  Even more interesting, in this same study, all those decreased indicators of CVD occurred in subjects with a LC diet who also had a THREE-FOLD INCREASE in saturated fatty acid (SFA) intake yet their SFA triglycerides and cholesterol ester measures were decreased, even further evidence that dietary SFA is not the devil is has been portrayed and that diets high in processed carbohydrates may be the culprit. (The authors of this study are highly regarded scientists in the field, so I will stand by the data they present based upon their reputations).

There is also a large body of research examining the effects of LC diets on epileptic patients. In a study in 1987, the authors found that patients who followed a ketogenic diet experience significant improvement in intractable seizures (6). Eleven years later, a LCKD was used as a treatment for children with epilepsy and the authors stated that, “A ketogenic diet should be considered as alternative therapy for children with difficult-to-control seizures. It is more effective than many of the new anticonvulsant medications and is well tolerated by children and families when it is effective” (7).

Last, and perhaps the most important as it is likely an underlying cause in all these cases is the link between high carbohydrate diets (specifically high in processed carbohydrates) and inflammation. This topic alone yields search results over 40,000 and 640 (according to google scholar and PubMed respectively).  While it is quite apparent that there is an association between carbohydrate intake and inflammation I will state it succinctly. Diets high in carbohydrate intake increase the levels of inflammatory markers in virtually everyone (8,9,).

References

1)  Boden G, Sargrad K. Homko C. Mozzoli M. Stein TP. Effects of a low-carbohydrate diet on appetite, blood glucose levels, and insulin resistance in obese patients with type 2 diabetes. Ann Intern Med. 2005; 142(6):403-11.

2) Volek J, Feinman R. Carbohydrate restriction improves the features of Metabolic Syndrome. Metabolic Syndrome may be defined by the response to carbohydrate restriction. Nutrition & Metabolism. 2005;2(1):31.

3) Westman E, Yancy W, Mavropoulos J, Marquart M, McDuffie J. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrition & Metabolism. 2008;5(1):36.

4) Feinman RD, Volek JS. Carbohydrate restriction as the default treatment for type 2 diabetes and metabolic syndrome. Scand Cardiovasc J. 2008;42(4):256–263.

5) Volek JS, Feinman RD, Phinney SD, Forsythe CE, Silvestre R, Judelson DA, et al. Comparative effects of dietary restriction of carbohydrate or fat on circulating saturated fatty acids and the atherogenic dyslipidemia of metabolic syndrome.

6) Kinsman SL, Vining EPG, Quaskey SA, Mellits D, Freeman JM. Efficacy of the Ketogenic Diet for Intractable Seizure Disorders: Review of 58 Cases. Epilepsia. 1992;33(6):1132–1136.

7) Freeman JM, Vining EPG, Pillas DJ, Pyzik PL, Casey JC, Kelly L and MT. The Efficacy of the Ketogenic Diet—1998: A Prospective Evaluation of Intervention in 150 Children. Pediatrics. 1998;102(6):1358–1363.

8) Seshadri P, Iqbal N, Stern L, et al. A randomized study comparing the effects of a low-carbohydrate diet and a conventional diet on lipoprotein subfractions and C-reactive protein levels in patients with severe obesity. The American Journal of Medicine. 2004;117(6):398–405.

9) Liu S, Manson JE, Buring JE, Stampfer MJ, Willett WC, Ridker PM. Relation between a diet with a high glycemic load and plasma concentrations of high-sensitivity C-reactive protein in middle-aged women. The American Journal of Clinical Nutrition. 2002;75(3):492–498.

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