Ketosis + IF – How Many Kcals to Consume [Situational]

Ketosis + IF - How Many Kcals to Consume


This write-up is part of a series that adds insight to the combo strategy of ketosis and intermittent fasting (IF) that I’ve been using over the past two years. In this specific post I’m providing a rationale for the amount of calories you should/may consume when switching to ketosis and IF and when you come from a different nutritional background – a higher carbohydrate diet with/without IF, a keto diet without IF, or any other protocol. Here we go…

How Many Kcals to Consume

If you are just starting out with either of these two strategies (intermittent fasting, ketosis), the combination of both, or if you’re just new to health optimization, I’d recommend first determining how many calories you are currently consuming, on average (I hate this word).

To do that, you can use any of the many web applications or phone apps designed for this purpose. I personally use Cronometer, which is a web and phone app. Many people use alternatives, such as MyFitnessPal or other apps. It’s a matter of personal choice.

Just plug-in the foods you eat in a day and see what caloric number they add up to.

Once you find out how much you eat in any particular day, I’d recommend using that same number of calories for the ketogenic diet and IF you are switching to.

More specifically: if you are currently consuming, say, 2,800 kcals/day, use the same calorie count when switching to ketosis and IF.

You can later reduce/adjust the number of calories if you feel so.

Often, when doing intermittent fasting with 2 meals during your feeding window you may have to force-feed to meet your pre-established number of kcals per day.

In my case, for example, I often find it difficult to consume 1,500-1,7000 kcals in two meals with my intermittent fasting of 18/6 (18 hours of fasting, 6 hours of eating – two meals). This makes my strategy highly satisfying/satiating and it allows me to strategically feast (3,000 – 5,000 kcals/day) every now and then.

It would be unwise to give you a specific number of calories that you should consume everyday because we are all different and we all have different daily energy requirements. Additionally to that, the hormonal behavior of each of us calls for different metabolic and energetic demands.

The only, somewhat, accurate way to find out how many calories you need in a specific day would be to spend 24 hours in a metabolic chamber (which is very uncomfortable and mostly unavailable – at the moment – to the wide public) – or with an indirect calorimeter and use extrapolation.

So, whenever a guru/expert/government tells you to consume this number of calories/day, run away. They do not grasp the complexity of the human metabolism.

The dietary guidelines of many countries suggest that normal weight, healthy, adult males, with moderate activity, should consume somewhere ~2,500 kcals, while normal weight, healthy, adult females with moderate activity should purpose for 2,000kcals. These suggestions, they say, are for weight maintenance.

But, from my point of view, you should not guide yourself by these values as they may be largely inaccurate…

Case in point:

I consume between 1,500 – 1,700 kcals per day and I train heavily many times per week. From the suggestions above, I should be constantly hungry and lose weight (fat and/or muscle) with my current strategy (IF + well formulated keto). Yet, I am very satisfied with my dietary approach (focus on micronutrient intake optimization) and my gym performance seems to be constantly improving.

Consider this: I often consume less than this amount of calories and I also often engage in strategic/situational feasting. This may make up for the apparent caloric deficit.


The major takeaway messages from this write-up:

  1. Find out how much you eat now (in terms of calories/day).
  2. Use the same amount of calories as you switch to ketosis and IF.
  3. You can later adjust (reduce or increase calories) if you want.

This write-up is part of my course and my recent book on intermittent fasting and ketosis. In both the course and in the book, I follow up with suggestions on how to approach the feeding window of your intermittent fasting strategy. If you’re interested, use any of the links provided above.

Image: here.

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2 Responses to Ketosis + IF – How Many Kcals to Consume [Situational]

  1. Stefan says:

    Great article for beginners with Keto/IF!

    “So, whenever a guru/expert/government tells you to consume this number of calories/day, run away. They do not grasp the complexity of the human metabolism.”

    Oh God, I wish more people would grasp this. Almost every time I read a statement like “a calorie is not a calorie” or “a calorie IS a calorie” I just want to facepalm myself.

    • Chris Chris says:

      I feel you Stefan. In very frustrated myself about this. But what we can do is to try helping others see the complexity of things and not judge or scold them 🙂

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