What you need to know about ketogenic diet

The ketogenic diet, also known as the “keto diet,” has become a popular eating pattern nowadays for many reasons. For many people, it is known for its magic to shred pounds off. The keto diet is very different from how most people normally eat. So before you even consider going “keto,” here’s what you need to know.


Comparison of macronutrient composition breakdown in general diet vs. keto diet

Macronutrient composition

Acceptable macronutrient distribution range (AMDR)

Ketogenic diet


45-65% of calories

5% of calories or 40-60 grams daily


10-35% of calories

1 gram per kilograms body weight


20-35% of calories

> 80% of calories


As shown in the table above, the macronutrient composition in the keto diet is very different from the general diet that many people normally eat. When eating the general diet in which carbohydrate consumption is rich, our body uses carbohydrates to make glucose to support bodily functions. In the case of keto diet, it requires most of its macronutrients to come from fat. This extreme shift in macronutrient composition results in a metabolic state called ketosis, in which the human body is forced to breakdown fat to make ketones for fuel instead of glucose because carbohydrates are so limited. This high-fat and low-carb diet emphasizes the consumption of all non-starchy vegetables, avocados, nuts, fats and oils, leafy greens, eggs, fish, meat, poultry, and restricts the consumption of processed foods, grains, desserts, sugar-sweetened beverages, and starchy vegetables. Most people can enter ketosis with less than 50 grams of carbohydrate intake daily, generally within 33 to 58 hours.


The use of keto diet

In the medical field, the use of this very low-carb diet is proven to treat epilepsy in adults and children who do not respond well to medication. Others use keto diet for a variety of health reasons. Based on available studies (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5452247/), keto diet may be associated with some improvements in cardiovascular risk factors, such as obesity, type 2 diabetes, and HDL cholesterol levels. However, these effects are time-limited and longer-term studies are needed to prove its efficacy.  


Side effects of keto diet

Since keto diet calls for an extreme shift in macronutrient composition resulting in an altered metabolism in the human body, potential consequences can happen. One of the most common issues is the “keto flu”  that arises in the first 4 to 10 days on this diet. It causes an array of symptoms including lethargy, muscle cramps and body aches, headaches, depressed moods, and gastrointestinal upset. On the other hand, food restrictions from legumes, grains, fruits and certain vegetables may decrease total phytonutrient and dietary fiber consumption, leading to severe constipation and negative effects on the gut microbiome. Other potential issues on a keto diet include kidney damage and micronutrient deficiencies. Therefore, targeted nutrition supplements may be required when going keto, including vitamin C, omega-3-fatty acids, magnesium, certain electrolytes, and more.


By Dorothy Ian Chan, RD / Hazel Ng, RD CDE


Copyright © | Bor S. Luh Food Safety Research Center  of Shanghai Jiao Tong University 2015