How many calories to eat while doing intermittent fasting?

Kst76 Posts: 923 Member
edited September 23 in Health and Weight Loss
I just started the 8-16 plan and I eat between 10 pm and 6 am. I work 3rd shift in a hospital. I have a couple of questions? How many calories should I eat. Somebody told me I don't have to count calories but that makes no sense. I try to eat about 12 to 1500 calories. Also, On the days I am off, is it ok to change my eating hours so I can eat with my family and sleep at night?


  • AnnPT77
    AnnPT77 Posts: 25,789 Member
    edited September 23
    Set up your MFP profile, and eat the number of calories it tells you to eat, when you set the weight loss rate at no more than 0.5% to 1% of your current weight per week (with encouragement toward the lower end of that range). Set your activity level based on your job and home life (not including intentional exercise). Log the intentional exercise when you do some, and eat those calories (or most of them, some standard fraction), too. (You don't have to eat them all that same day. You can save some up for the next day or the weekend, if you wish.)

    Follow that for 4-6 weeks. If you have menstrual cycles, go for at least one full cycle, to compare body weight at the same relative point in at least two different cycles.
    Compare your average weight loss per week to your weight loss rate goal. If necessary, adjust your base calories (up or down) to reach a sensibly moderate average weight loss per week, using the assumption that 500 calories per day is about a pound a week. Keep checking periodically as you go forward from there, and adjusting if necessary.

    This is what you do when losing weight with IF, or losing weight without IF. IF should not make any significant difference in what calorie level you can eat. (For some people, it helps make eating the right calorie level easier. If that's true for you, it's a good weight loss strategy for you.)

    Best wishes!

    P.S. The reason some people say you don't need to count calories with IF is that some people find it helps them so much with appetite control that they eat fewer enough calories that they lose weight without actually counting the calories . . . or they've been persuaded by someone else who had that experience. Quite a few people here using IF find they do need to count calories, though others don't.
  • Retroguy2000
    Retroguy2000 Posts: 293 Member
    Someone told you wrong. You'll only lose weight in a calorie deficit.

    On MFP, enter an estimate for your daily activity (sedentary, active, etc.) and tell it how much you want to lose. That's your target during 16:8.
  • Kst76
    Kst76 Posts: 923 Member
    Thanks guys. I used to be active here and Now im back. I know about the CICO and that is why when I was told calorie intake don't matter it made no sense.
  • neanderthin
    neanderthin Posts: 7,961 Member
    Kst76 wrote: »
    Thanks guys. I used to be active here and Now im back. I know about the CICO and that is why when I was told calorie intake don't matter it made no sense.

    Yeah, exactly. Calories matter simply because if you're not in a deficit you're not going to lose weight. Generally, the reason someone picks an eating window is for convenience, so switching makes perfect sense.
    BBIPAD Posts: 13 Member
    Thank you
  • lgfrie
    lgfrie Posts: 1,450 Member
    edited October 2
    I've been doing IF for over 3 years. I started in May 2019 and have been more or less on the IF train ever since, with months here and there where I either intentionally took some time off, or unintentionally went off the tracks for a while.

    For me and my wife, IF has been the only approach that has ever worked to lose weight and keep it off. We've had many failed diets, or "successful" ones that were undone from inability or lack of motivation to stick with it. IF suits us. After much experimentation, we do 17:7, that is, noon to 7 pm, and not a single calorie outside the eating window. Using that approach, we've been able to lose around 70 lbs each and keep it off.

    I do believe that IF offers benefits beyond just providing a structure to achieve a caloric deficit, and my doc certainly agrees. These non-weight-loss potential benefits are worth discussing with your doctor or other medical professional, as the rabid opinions for and against that exist in forums are not super-helpful. That said, as concerns weight loss specifically, you will lose weight precisely in accordance with your calorie deficit. If 1300 cals will get you a 1 lb per week weight loss, it'll do so whether you eat them throughout the day or in a window. If your only goal is weight loss, IF may give you the structure you need to keep a deficit going. It works for some people and not others. My sis has not been able to make IF work and is very obese, whereas my wife and I are true devotees. It just depends on the person.

    When I started IF, I followed the strict protocol of doing the same eating window every day. It worked until it didn't work, and then it kind of nosedived when the plan bashed head-on into my social life and need to be able to hit the pause key. I think being a little flexible with it is a good idea. For instance, taking a night off so you can eat with family or friends or just get a break. The trick is to get back on the IF horse the next morning, because it is EASY to fall out of the IF framework and can be hard to restart it if it gets too far in the rear view mirror. My method now is to try to stick to the noon to 7pm window around 27 days per month, and have a day a week that's more flexible, but not assigned in advance - not like "every Saturday" but just when I have a need for a break, such as date night out.

    Weight loss is CICO. IF won't directly impact it. But IF can indirectly impact it and be life-changing, if you stick with it and sort of get in the rhythm of IF-based eating.