Calorie counting is not really necessary on a ketogenic diet. It would seem that as long as you keep your carbohydrate intake super low, and your protein intake moderate, you shouldn't have to worry about calories.
It is true that a ketogenic diet is very satisfying, and after you adapt to ketosis, you'll find you just aren't as hungry as you were when you ate lots of carbohydrates. Ketones have a damping affect on the appetite, and most people spontaneously reduce their food intake when they eat a high fat diet.
However, for some people, myself included, it may be necessary to track calorie intake. There are two ways to do figure out how much of each macronutrient (fat, protein, carb) as a percentage of calories :
I think the second way is the better way and I'll explain why, but let's explore the first way.
You can set calories on the ketogenic percentage ratios of about 70% of calories from fat, about 20% from protein, and under 10% from carbohydrate.
Here's an example on how to do it.
Let's say you set your total calorie intake for the day to be 1500. Here's one way to calculate how many grams of fat, carb and protein to eat:
Another way to set calorie intake is to start with protein requirements, and I think this is the better way. Here's why:
Total daily protein needs should always stay the same no matter how many calories you choose to eat in a day. Using percentages to set intake can be misleading if calorie intake is very low or very high. For instance, say a person weighs 200 pounds, but they want to weigh 160 pounds. They decide to eat 1200 calories a day in order to lose weight. Do they set protein requirements on 200 pounds or 160 pounds?
The best choice here is to set protein requirements on a reference weight on either lean body mass (if known) or on ideal or goal body weight. This method is more accurate in providing enough protein to support lean body muscle mass but not so much as to increase blood sugar.
The general formula for protein grams per day is 1 gram of protein per kilogram of reference weight. So in our example, we would convert pounds to kilograms by dividing pounds by 2.2 (and then multiply by 1 gram, which gives the same number).
160/2.2= 72 kilograms of weight
So this person should shoot for about 72 grams of protein per day. Now as you can see, this is pretty close to the 20 percent measure from above.
Now let's explore how changing protein or calorie amounts can affect percentages. What happens if
Look at percentages as calorie intake changes. If we were to stick with the 20 percent rule above, it would result in different protein intakes depending on calorie intake:
If this person were a big guy with lots of muscle mass, he might not get enough protein each day on 60 grams. But if it were a small woman who wanted to eat 2000 calories a day to maintain her weight, 100 grams would most likely be too much protein on a ketogenic diet. This is why it's better to start with a static amount of protein grams to make sure you eat enough to support your lean body mass or ideal reference weight.
Now let's look how protein gram amounts affect percentages when calorie intake is static:
You can see why it's misleading when dietitians insist that protein intake should be a certain percentage of your calories when they have no idea of the calorie intake.
One more example of why percentages can be misleading when protein intake is static:
As you can see, even though the protein intake is exactly the same, I've seen dietitians get concerned about a "high" protein intake at 27%, when no caloric reference is given. This is also probably why so many people think that low carb diets are high protein diets because they are judging by the percentage of protein without thinking about calorie intake.
Calorie counting is helpful sometimes just to figure out the above information, and to figure out how much fat to eat each day. Because carb and protein grams are static numbers daily, fats become the macronutrient that can be manipulated to change caloric intake.
Because your carb count is so low on a ketogenic diet, you have to limit the higher sugar vegetables (squash, peppers, tomatoes) and fruits. And of course, any product made with flour or sugar is totally out.
Calorie counting can be helpful, but there are caveats, as discussed above. If you wondering what foods are best to eat, see this low carb food list for examples of the foods which are allowed on a ketogenic diet plan.
To track your food values and intakes, you can use the free database at the USDA website, or pick up a food counter book that gives you the calorie, carb, fat and protein counts in common foods. Or you can buy a piece of software like Fitday or an online calorie counting service to help you keep track.