Understanding the Low Carb Science

While the ketogenic dietary lifestyle is surging in popularity, it’s not new. In fact, doctors were prescribing low-carbohydrate diets to patients as far back as the late 1800’s as a way to improve health & reduce bodyfat. As I’ve traveled on my low-carb/high fat (LCHF) journey, evolving into practicing the ketogenic dietary lifestyle (KDL), one of the most puzzling aspects for me is how much scientific research has been done to demonstrate the power of LCHF, that has not been shared with the broader population. I aim to change that with this reference page on http://www.business-fit.org, in the hopes that people who are interested-in, curious about, or have preconceived notions regarding LCHF and KDL, will be able to use this site as a reference and data-based resource guide to see the research that proves the power of these lifestyles for themselves.

LCHF vs. KDL: What’s the Difference?

You will, even in the below research papers, see medical and research professionals use LCHF and KDL interchangeably, which is simply inaccurate. They are not the same, and as a foundation, it’s important to understand the differences.

On the LCHF diet, the general guidance is to consume no more than 130 – 150 grams of carbohydrates per day, which using a 2,000 calorie/day diet, means approximately 25% – 30% of calories from carbohydrates. The remaining 70% of calories will be consumed from fats & proteins in a ratio of 50% – 60% fat / 10% – 20% protein. On this diet, the body still has ample carbohydrates to operate with glycogen (glucose stored in the muscle) as the primary fuel source, except in instances where glycogen is being aggressively depleted, such as with high performance athletes.

On the KDL, the general guidance is to consume no more than 40 grams of carbohydrates per day, which using a 2,000 calorie/day diet, means 5% – 10% of calories from carbohydrates. The remaining 90% of calories will be consumed from fats & proteins in a ratio of 65% – 80% fat / 10% – 25% protein. Some KDL practitioners may increase their protein consumption up to 30% of calories, but that would be the ceiling. On this diet, the body shifts from burning primarily glycogen to ketones (fats) as fuel. Basically, fat becomes the primary source of fuel, and as the body needs a small bit of glycogen, it is very-well equipped to convert other molecules (ie, lactase, proteins, fats) to energy through processes like lipolysis and gluconeogenisis.

A good starting point in seeking out references on whether the LCHF dietary lifestyle is safe and effective is to review the below published article. In addition to providing a synopsis of research that answers questions about safety, weight loss, type 2 diabetes impact & the contribution (or lack there-of) to cardiovascular disease, there are well over 100 references and acknowledgements that can take you into more detail at you leisure. There is likely a lot more research around this lifestyle than you may have thought, and the results around the health benefits are surprisingly consistent and powerful.

https://bjsm.bmj.com/forward/emailref?path=node/105230

Research, Studies, Meta-analyses & Trials: Understanding the Science

The below reference list is divided into sections of interest in an effort to show just a sample of the depth of scientific rigor that has been applied to LCHF and KDL lifestyles. The sections are as follows:

  • Weight Loss
  • Type 2 Diabetes (T2D)
  • Metabolic Disease / Metabolic Syndrome
  • Fats & Inflammation

Weight Loss

(2004). A randomized trial. The national cholesterol education program diet vs a diet lower in carbohydrates and higher in protein and monounsaturated fat. https://pubmed.ncbi.nlm.nih.gov/15505128/

(2007). A randomized trial. Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women – The A TO Z Weight Loss Study. https://jamanetwork.com/journals/jama/fullarticle/205916

(2013). A meta-analysis of randomized control trials. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss. https://pubmed.ncbi.nlm.nih.gov/23651522/

(2015). A meta-analysis. Dietary Intervention for Overweight and Obese Adults: Comparison of Low-Carbohydrate and Low-Fat Diets. https://pubmed.ncbi.nlm.nih.gov/26485706/

(2016). A meta-analysis of randomized control trials. Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors. https://pubmed.ncbi.nlm.nih.gov/26768850/

Type 2 Diabetes (TD2)

(2005). Small Control Study. Ketogenic diet to treat T2D. https://pubmed.ncbi.nlm.nih.gov/16318637/

(2013). Meta-analysis. Dietary approaches to managing T2D. https://pubmed.ncbi.nlm.nih.gov/23364002/

(2017). Randomized Trial. Twelve-month outcome diet comparison of adults with T2D. https://www.nature.com/articles/s41387-017-0006-9#Sec7

(2019). Virta Health 2-year Study. Evidence to support a ketogenic diet to reverse T2D. https://www.virtahealth.com/blog/2yr-t2d-trial-outcomes-virta-nutritional-ketosis

Metabolic Disease / Metabolic Syndrome

(2003). Data review. Clinical use of a carbohydrate-restricted diet & metabolic syndrome. https://pubmed.ncbi.nlm.nih.gov/18370666/

(2008). Randomized Control Trial. Long-term effects of a very low carbohydrate diet. https://pubmed.ncbi.nlm.nih.gov/19439458/

(2009). Randomized Control Trial. Carbohydrate restriction vs. low fat on metabolic syndrome. https://pubmed.ncbi.nlm.nih.gov/19082851/

(2012). Meta-analysis. Low-carbohydrate diet and cardiovascular risk factors. https://pubmed.ncbi.nlm.nih.gov/22905670/

(2021). Article from the American Journal of Clinical Nutrition. The Carbohydrate-Insulin Model & the Obesity Pandemic. https://academic.oup.com/ajcn/advance-article/doi/10.1093/ajcn/nqab270/6369073

Fats & Inflammation

(2005). Editorial. Obesity & Visceral fat: a growing inflammatory disease. https://www.nature.com/articles/ncpgasthep0197

(2014). Randomized Control Trial. Advice to follow a low-carbohydrate diet has a favorable impact on low-grade inflammation. https://pubmed.ncbi.nlm.nih.gov/24779961/

(2020). Blog post written by Healthline Nutrition Team Member, Adda Bjarnadottir. Five studies done to demonstrate no link between saturated fat and heart disease. https://www.healthline.com/nutrition/5-studies-on-saturated-fat