Intermittent Fasting

I’m new to, and confused about, intermittent fasting. I’m hoping someone may be able to help. I’m not sure I understand the idea behind it.

if someone eats breakfast at 7 AM, then lunch at noon, then dinner at 4 PM, then goes to sleep and wakes up the next day to do it all over again, is that an “eating window” of 9 or 10 hours? Isn’t that just called a normal day? What am I missing? Why do we need timers and gadgets for this? I mean this app has an entire section devoted to this. I know there has to be more to it, it’s all over everywhere, so what am I missing?

Pain is inevitable. Suffering is optional.


  • I'd overeat if I allowed myself to eat just about anything for 9 hours per day.

    OMAD (One meal per day) seems like it would be realistic calorie-wise, but then you need to be OK with being hungry much of the day.

  • Yeah, I get that. I meant that a normal breakfast, lunch, dinner, 3 meals a day seems to be intermittent fasting. I’m not sure I understand what the idea is with it.

    Pain is inevitable. Suffering is optional.

  • The idea behind IF is that you'd limit your food consumption time window enough that you'd actually end up consuming fewer calories per day.

  • edited October 2020

    The point of IF is to clear your glycogen stores, which is about 1000 calories. So it takes about 14 hours. So you need to fast for 16 hours to get any benefit. Once your stores are depleted, your body has to burn fat.

    You don't NECESSARILY have to consume fewer calories. You can easily eat 3 full meals in 8 hours. I'm currently losing weight, so I eat 2 meals; but during maintenance you don't eat fewer calories.

    Eating is inflammation. The longer you allow your body to do stuff other than digesting food the more time it can spend repairing cells and doing other things that need to be done.

    I eat 1 meal a day once a week and do a 16-18 hour fast at least every other day. I rarely eat before 5pm. My resting heart rate is down 10 bpm and stress is greatly reduced since I started 6 months ago.

    Realize that after you eat, you're digesting for 3 hours. So you're not really fasting the second you take the last bite.

  • @CalorieGuru

    I think the overall concept of what you're saying has some truth but there's no way that fasting is depleting glycogen stores.... Especially, if there wasn't any intense cardio activity before the fast (remember, we store glycogen in both our liver and muscles). While glucose is a preferred fuel source, we traditionally burn a mix of macros at rest.

    Also, eating isn't an inflammatory process per se... Certain food components (especially saturated and trans fat) are considered inflammatory but we can only obtain anti-oxidants by ingesting food - fruits, vegetables, nuts, seeds, etc.

    Intermittent fasting can assist weight loss by placing rules around the window of eating. And if you're not providing your body with regular nutrition, it does have to catabolize itself to continue to produce energy so the reliance on fat as fuel will increase.

    Kind regards,

    Susan Macfarlane, MScA, RD
    Registered Dietitian Nutritionist
    As always, any and all postings here are covered by our T&Cs:

  • This is just wrong. You need to bone up on IF; I think your education is outdated. The metabolic switch from lipid/cholesterol synthesis and fat storage to mobilization of fat through fatty acid oxidation and fatty-acid derived ketones from fasting or carbohydrate deprivation is well documented. "Intense exercise" accelerates the process; without it the switch will occur from 12-14 hours after intake.

  • Thank you all for your responses. It seems that I’ve been doing intermittent fasting for most of my life without knowing it. Breakfast in the morning, lunch at mid-day, and dinner in the evening, all within a normal day of 8-9 hours. Seems just normal to me.

    Pain is inevitable. Suffering is optional.

  • @p0wer_lifter

    The research on eating breakfast is pretty mixed. I typically leave it up to the individual to decide whether or not breakfast is beneficial to them or not. As long as someone is healthy, achieving fitness goals, and meeting their nutrient needs, I'm a content dietitian. :)

    Susan Macfarlane, MScA, RD
    Registered Dietitian Nutritionist
    As always, any and all postings here are covered by our T&Cs:

  • I’m trying intermittent fasting, for about a month and a half now, and loving the results. I’ve never been a big breakfast eater, but I was a late night snacker, especially when stressed.

    So far, I haven’t set myself a schedule, just gone with what felt good. My shortest fasts have been about 14 hours, and my longest between 24-36 (once per week). My average is 18 hours 40 minutes, usually eating two meals during my eating window. I generally include activity such as walking, dancing, or swimming during my fasting periods.

    I’m finding for me, it avoids those calories from “sure lets get ice cream” or the handful of pretzels or glass of wine before bed. Because I’m not snacking at night, my nighttime heartburn seems to have improved as well.

    I’m not finding that I am overly hungry while fasting, even on the days when I do a longer fast.

    I am finding it is hard, over the course of an average week, to actually average my calorie target without eating junk (I did too much of that before and while I’m not denying myself small amounts of things I enjoy, I’m not going to eat them just to hit a target if I’m stuffed on foods like veggies and lean proteins and not craving anything else.)

    At this point, I’m feeling good, not feeling deprived, tired, etc, and am using a multivitamin in an attempt to avoid any vitamin or mineral deficiency. I am losing more than two pounds per week, but, I have a lot to lose, and I am not seeing any signs my body isn’t adjusting to the new routine. (Skin, hair, nails, fatigue level all good. Average resting heart rate slightly lower with less weight and more exercise. Blood pressure has never been bad. Haven’t had any cholesterol tests, etc since starting.)

    I guess two questions…

    Should I be concerned I’m, on average, having trouble meeting the targets for -2 pounds per week without feeling overfull or eating high calorie junk foods?

    Any other suggestions to help someone new to intermittent fasting?

  • Ignore the targets. If you are eating until you are comfortably full twice a day, that's enough for your body. The calorie count/burn numbers are hugely inaccurate, people shouldn't rely on them.

    Be a little conscious of protein though. A typical 100g (3 1/2 oz) serving of meat would have about 25g of protein, and I think 50g would be the bare minimum a day (I strive for more), so it would be easy to eat too little protein.

    Stick with it. I have been doing it for 22 months, and don't think I will go back.

    The thing is, we have been told for years that eating raises our metabolism, that breakfast is the most important meal of the day, that we should eat 3 meals and three snacks a day etc etc. I even saw advice on here to snack just before bed 🤯 So it needs a name, so people do it.

    But you are right, it's just normal eating. I gentle coach people on starting IF on other forums, and suggest starting at 12:12 aka "like your grandparents ate". I think your pattern of eating dinner at 4pm would be unusual amongst modern humans.

    Of course, IF can be much more than that, but you naturally follow it now. Very sensible you didn't listen to nutritionists!

  • I completely agree about the protein, especially since I don’t want to lose too much muscle with losing weight more quickly. Ive been trying for 100g, with limited success, but usually manage 70-90g a day. I’m also trying to vary my sources, and not get in a “chicken breast rut” like I have in some past attempts at dieting. Lots of omelets, seafood, chicken, venison, and bison. Some nuts, seeds, and dairy mixed in for variety and travel convenience.

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