What are the rules for ketogenic diets?

posted in: Enhancing Ketosis

There are a lot of different ketogenic diets out there, but at the core they are all about limiting carbohydrates. There is always an induction phase where your body adjusts to the diet.  As you stop eating carbs and you start burning through your stores, most people have symptoms of what has been called “keto flu”. 

This is a combination of dehydration, electrolyte imbalance, and the starvation response to no carbs. Once your liver makes enough ketones to supply your energy needs, these symptoms go away.  See “Keto Flu” for the whole article.

Once you are completely in ketosis, all you need to do to maintain it is to not eat carbohydrates.  OK, it’s not that bad.  You can eat 20 grams of carbohydrates a day during induction and upwards of 50 without breaking ketosis if spread out over the day (non-dieting maintenance phase).

The specific diet you choose will dictate which carbohydrate sources are “good” and how much of them you should eat (Atkins, Paleo, etc.). For the type of keto diet to choose, please see “What are the types of ketogenic diets?”.

Protein intake rules

Protein is the most straight-forward macro when it comes to ketogenic diets.  It is absolutely needed for bodily repairs and many amino acids (what makes up proteins) are only available through diet.  Your body cannot produce them on their own.  These are called Essential Amino Acids, so you need to make sure your protein sources contain them. 

Foods with all of the 9 EAAs are called Complete Protein foods.  This is particularly important for Vegans and vegetarians, as most plant-based proteins are missing one or more EAAs and need to be supplemented with another plant protein that has the EAA that is missing from the first. The two or more proteins used together should cover all 9 EAAs.

Ideal protein intake will depend on your ideal lean body mass. You can do the calculations pretty easily online.  First, calculate your Ideal Body Weight HERE.  One you have a ballpark number (the calculator uses multiple formulas, so I do a rough average of them), you plug it into the weight box of the Protein Calculator HERE.  We recommend staying above the World Health Organization recommended safe lower limit results. 

Now you have the minimum amount of protein you need ingest daily (as long as they are Complete Proteins).  The results are dependent on the data you enter, so be accurate with your activity level.  The more active you are, the more protein you will need.

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Fat intake rules

Fat intake is a little more complicated, more due to the amount of fat eaten than the type.  Although there are Essential Fatty Acids that the body needs to ingest, they are common in vegetable oils, nuts and seeds, so are typically not difficult to find. They are also present in oily fish, so they can perform double duty as both a protein and a fat source. 

One of the hardest parts of using ketogenic diets for weight loss is getting enough fat into the diet.  Westerners have grown up in a world where fat is demonized and carbohydrates are the primary form of energy.  Changing that mindset is difficult and one of the mistakes people new to keto make is to avoid eating adequate amounts of fat.

Even with a loose interpretation of keto rules, fat should account for a minimum of 65% of your calories.  As we discussed in “What are the types of ketogenic diets” in the high-protein diet, 65% of calories coming from fat is barely ketogenic, if at all.  The formula is


Anything less than an answer of 1 is minimally to non-ketogenic.  >2 is preferred and >3 is a medical level keto diet. This can be used to evaluate individual meals as well. If you know you are at or near a “1”, you can add a little more fat to the meal to make it ketogenic, you only have to watch the calories then. 

Fat is your main source of calories, so when considering weight loss, your calories still need to be less than the number of calories you burn every day.  At 9 calories per gram of fat, those calories add up fast.

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Carbohydrate intake rules

Carbohydrates are the final macro to look at, but they are the most important thing about ketogenic diets.  You have to eat as few net carbs as possible.  See “What are Net Carbs and why do they matter” for a discussion about what should be calculated.  Once fully in ketosis, your body does not technically need carbohydrates as food. 

You will have a very hard time eliminating net carbs altogether due to their inclusion in almost all non-protein food sources, but by focusing on low net carb vegetables, you can get them pretty low.  See “What is a no carb diet and is it safe”. Various foods with low net carbs can be found referenced in “What can you eat on a ketogenic diet?”.

In order to safely stay in ketosis, especially while you are new to keto, you should keep your net carb consumption under 20 grams per day.  It is also recommended to spread those out over the course of the day and avoid added sugar as much as possible. 

For those not trying to lose weight, you might be able to get as high as 50 grams per day if you are somewhat active and you are not worried about cycling in and out of ketosis, which is dependent on how long it has been since your last meal. 

The golden rule of keto is 20 grams of net carbs or less per day. 

If I had to sum up the Standard Ketogenic Diet formula in one sentence, it would be this:

Add the grams of protein you need every day to the number of carbs you will allow yourself and multiple that by 2 (or 3 if you are wanting to lose weight quickly).  That is the number of fat grams you need to eat every day to optimize ketosis.  

Ketogenic diets are great for fat loss.  Your body uses its fat stores for energy supplemented by the fat you eat.  It is efficient and fast, if done correctly.  However, if you don’t follow the keto rules, there are consequences. 

If you are knocked out of ketosis due to having a few too many carbs, you will not be losing weight until you have burned off the carbs completely and go back into ketosis.  If it is by a minor amount, you may be back in ketosis quickly.  If you eat more carbs, especially for a cheat day (see “What is a keto cheat day?”) you may be out of ketosis for hours or even days. 

The entire time you are out of ketosis, you will not be burning fat, you most likely won’t lose weight, and quite possibly could gain weight.  If you eat a high-fat meal while not in ketosis, most if not all fat calories will be stored as fat in the body to be burned off later. 

All of the carbs from that meal will also delay getting back into ketosis even longer. Most of the people that don’t lose weight on keto, aren’t doing it right, whether not enough fat or too many carbs.  Don’t forget to check for hidden carbs too, especially in processed foods. 

If you truly follow the rules of ketogenic diets and don’t eat too many calories, you will lose weight.

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*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

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