The ketogenic (“keto”) diet is growing in popularity (just check out the Google Trends report below!), but it might not be right for everyone. Read on to discover what registered dietitian, Suzie Cromwell, has to say:
What is it?
The keto diet is a high fat, moderate protein and very low carbohydrate diet. It was developed in the early 1920s as a treatment for epilepsy in children (1). There are a few variations of the diet: the Classic Ketogenic diet, the modified Atkins diet, and the low glycemic index diet. All three recommend limits on carbohydrate rich foods such as starches from both refined and whole grains like breads, cereals, crackers, rice, pasta, starchy vegetables, beans, legumes, and most fruit.
So what can you eat on a keto diet? Most keto diets include foods high in saturated and unsaturated fats.
Sources of saturated fats include:
- heavy cream
Sources of unsaturated fats include:
- olive oil
What does it looks like?
The ketogenic diet typically reduces total carbohydrate intake to less than 50 grams per day (2)—this is equivalent to a small bagel—and can go as low as 20 grams per day. Protein intake is moderate to preserve lean body mass and maintain diet induced ketosis (where the body can convert amino acids in protein to glucose for energy).
The classical version typically provides 80-90% of energy from fat and 10-20% of energy from carbohydrates and protein combined, amounting to a macronutrient ratio of 3:1 or 4:1 (fat: protein and carbohydrates) (1). The modified Atkins and low glycemic index diets have a less restrictive approach, however, with 60-65% of energy from fat, 5-10% of energy from carbohydrate and 25-35% of energy from protein.
How does ketosis work?
With limited availability of carbohydrates, the body metabolizes fat rather than carbohydrates to provide energy. The liver converts fat into fatty acids and produces ketone bodies, which replace glucose as a primary source of fuel. The dietary accumulation of ketones in the blood is also known as nutritional ketosis (3).
What are the therapeutic roles of the keto diet?
Emerging research has shown promising results in various conditions. The ketogenic diet has had favourable impacts on neurological disorders such as epilepsy, Alzheimer’s and Parkinson’s disease; cancer; obesity and endocrine disorders such as type two diabetes and metabolic syndrome (3).
Several studies have shown the use of ketogenic diets as an effective weight loss therapy in the short term along with improved insulin sensitivity, blood pressure, waist circumference, and cholesterol.
There are various theories regarding the mechanism of weight loss. Some suggest it may be related to:
- the satiating effect of fat and protein in the diet,
- suppressed appetite due to altered levels of hormones such as ghrelin and leptin while on a low carb diet,
- the direct hunger reducing role of ketone bodies—the body’s main fuel source on the diet; or
- the cost of energy required to convert fat and proteins to glucose (2,3,4,5).
What are the considerations?
Maintaining a ketogenic diet can be challenging and requires commitment. The adjustment period as the body shifts to an alternative metabolic pathway may last days to weeks, and the potential side effects during this time may include hunger, fatigue, headaches, irritability, constipation and “brain fog”. This can be managed with adequate fluids and electrolyte repletion. Keto is a restrictive diet that requires planning and meal preparation especially around holidays, travel and social events. Currently there are limited studies assessing the long-term effects on health.
Excluding whole food groups may lead to possible nutrient deficiencies over time. Some nutrient considerations are fibre, B vitamins, vitamin D and minerals (iron, magnesium and zinc). It is important to include a variety of foods in each food group that are permitted on the diet to minimize these risks; adding a multivitamin with mineral supplement may be beneficial (6).
Is the diet right for you?
Bottom line, the keto diet is not for everyone. It is always recommended to consult with a physician and dietitian before initiating a keto diet to monitor your bloodwork and to minimize nutrient insufficiencies.
- Sudha K, Elizabeth N, Carol C, Eric K. Dietary therapy for epilepsy: future research. Epilepsy Behav. 2011 Sep: 22(1):12-22.
- Paoli A, Rubini A, Volek JS, Grimaldi KA. Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. Eur J Clin Nutr. 2013 Aug;67(8):789.
- Gupta L, Khandelwal D, Kalra S, Gupta P, Dutta D, Aggarwal S. Ketogenic diet in endocrine disorders: Current perspectives. J Postgrad Med. 2017 Oct;63(4):242.
- Paoli A. Ketogenic diet for obesity: friend or foe?. Int J Environ Res Public Health. 2014 Feb 19;11(2):2092-107.
- Abbasi J. Interest in the Ketogenic Diet Grows for Weight Loss and Type 2 Diabetes. JAMA. 2018 Jan 16;319(3):215-7.
- Diet for review: ketogenic diet for weight loss. Harvard T.H. Chan School of Public Health. https://www.hsph.harvard.edu/nutritionsource/healthy-weight/diet-reviews/ketogenic-diet/
Suzie Cromwell is a Registered Dietitian now working part-time at Elaho Medical Clinic. She completed her Bachelor of Science in Food, Nutrition and Health at UBC, and following her graduation she completed an extensive integrated internship with Fraser Health Authority at both Royal Columbian and Burnaby Hospitals. Suzie is registered with the College of Dietitians of British Columbia and is a member of Dietitians of Canada.
Her scope of expertise includes: healthy weight loss and maintenance, the prevention and management of various chronic diseases (including Diabetes, Kidney, and Cardiovascular disease), and the effective management of digestive issues (including IBS, IBD, and Celiac Disease); as well, she has a special interest in Sports Nutrition.