If this is answered elsewhere on the sub please just link the post.
Let’s say an app like MFP says I need to eat a max of 1980 calories per day in order to lose 2 pounds a week.
What’s the difference between fasting for 18 hours and eating the 1980 calories within the 6 hour window, versus spreading those 1980 calories out through the day by eating at breakfast, lunch, and dinner?
Thanks in advance.
Having done a 100 lb weight loss journey and keeping it off for 7+ years I have learned a lot about myself mentally and emotionally. From a calories in vs calories out perspective there is likely no difference, but from a mental edge perspective it is significantly easier to diet long term by shortening your eating window. During your fast, any hunger/craving issues eventually pass and you can continue your day not focused on being hungry. Additionally when you do eat, you will feel satisfied. Spreading a calorie deficit out over the entire day will likely (at least for me) mean fighting hunger the entire day because you are rarely satiated.
Your blood sugar stays high and your body is in energy storing mode if you are constantly eating throughout the day. Something like that but maybe not in those words. When you are fasting for 16 or more then the body is able to switch from food energy to glycogen stores on the body for energy in the liver and muscles doing a thing called glucogenesis.
Once those energy stores are used up, then the body switches to body fat and does a different thing called ketosis. To reach ketosis from what I remember reading and seeing here and there is that you would need a fast in the 20 hour range or higher, something like that.
I just have a rough idea on this stuff and am still learning. Been doing IF since 2/2/23 and am at 167.8 pounds from a starting weight of around 176 pounds. 18 hours fasting and 6 hours eating is what I do.
A couple times during the work week though the fasting becomes 20 hours or a little more than that if its busy and thats fine, I still stop eating at 6pm anyways. Also I do one scheduled 20 hour fasting day regardless if Id done anything close to it during the work week, and thats Friday 6pm to Saturday 2pm fasting and then I’ll eat till 6pm. Been able to stay in a caloric deficit the past three or four days too, I think that helps with weight loss long term as well.
I’m trying to avoid a T2D diagnosis, so I say that there is a huge difference, and it’s all about insulin.
Insulin is a hormone that enables fat storage (specifically it’s antilipolytic; anti fat burning). Insulin is released every time we eat (unless you have T1D and require exogenous insulin to survive). So eating all day = releasing insulin all day = fewer opportunities to use your body’s own fat stores for fuel.
But! For the record, we secrete and use insulin at different rates. I just know that it is an issue for me, and intermittent fasting isn’t about calories. It’s about giving my body time to reduce insulin each day. Plus, I quite enjoy the mental break about not fussing about my food (I manage my family’s meals, and that’s plenty).
It’s actually a topic of hot debate on whether there is a difference or not. Many studies have shown that there is not a difference for weight loss, that long-term weight is strictly a matter of calories in - calories burned. How you arrange them throughout the day has no impact.
However, other studies have shown that your metabolism revs up after you start to eat, and that your body potentially prioritizes different energy stores (ie fat vs muscle) depending on how long it’s been since you last ate. The evidence for this is inconclusive, really.
What is true, though, is that for many people, setting a small eating window is a simple and easy way to limit calorie intake during the day. So regardless of whether the metabolism effects are real, IF is effective for many people because it’s easier than counting calories.
No difference as far as weightless goes. It’s harder to eat more when you’re fitting everything in an eating window if you’re making healthy food choices. This is why fasting is great for weightless. This is mainly why I do intermittent fasting. It’s way harder for me to binge and over eat if I’m sticking to my eating window. I also just feel better doing IF. Not mention the other benefits it offers.
To keep my weight under control when it’s already gotten out of control, I desperately have to go extreme Fasting to bring down blood pressure issues! Been getting all the symptoms that go w/ it all at once; headaches that come & go, pounding in the ears, elevated heart rate doing the simplest of chores, periodic bouts of GOUT! - I think spreading out the meals is more for maintenance than actually getting the full benefit of FASTING! Multiple spikes of Insulin due to intake of anything outside an eating window defeats efforts to losing weight IMO! ;-)
Weight loss will always come from burning more calories than you consume, IF is just another way to do it. There are benefits to doing IF even if not wanting to lose weight, but for those whose goal it is, it’s just an easier way to limit calories.
You’ll see a lot of people post they’ve been doing it for a month, 2 months, etc and not lost anything. Some thing they can just shorten their eating time, but eat whatever they want, that’ll never work. A friend tried and quickly gained 10lbs