Perhaps, but for some people it's also a physiological risk. I eat about 1200 calories for breakfast as my body otherwise cannot function for the day.
Whether fasting is appropriate depends on one's body composition, daily exertion routine and physiological factors. For most people I'd recommend exercise instead of fasting.
"You can't outrun the fork."
Metabolic studies show that you have to be damn near Olympic calibre in your exercise routine to cause a significant change in caloric consumption by increasing metabolism through exercise. Your body pretty much holds a constant level of metabolism and shunts it around to whichever systems it deems most important right now.
Exercise might give you an extra couple calories of margin (maybe), but you won't lose weight with it alone.
If you want to lose weight, you have to get the caloric intake down. And that's hard because you are fighting biological systems that evolved to store energy really efficiently and to give up that energy only very reluctantly.
Anecdotally, my appetite became more reasonable after I took up running. Fat seemed to keep me full longer.
For example running or swimming for an hour seems to be around 8-900 kcal based on various websites.
Now that's not nothing, but also people won't do it daily for sure. I think nutrition advice is really hard because people already (have to) factor in the likelihood of following the advice by a general average person, their propensity to lie to themselves to be in denial, etc. If you actually (not just in your daydreams) do a lot of daily exercise (not just drive to the gym and read Facebook), it will matter in terms of calories.
I'm not saying this to counter your advice. Advice is hard, it is tangled up in motivational systems etc. but sometimes people may get the wrong idea in the other direction. It is true that exercise cannot make up for bad eating habits especially if you eat back more afterwards because you believe you earned this. I think that whole type of relationship to food is unhealthy (junk binge is reward, fast and exercise is punishment). A few sit-ups won't undo a chocolate chip. Etc etc. But regular exercise all else equal does have a significant effect. Yes, nothing is all else equal, but then we end up making so many assumptions on how people will react that the whole debate is infused with assumptions like, but then you will lie to yourself and actually follow the opposite advice and so I need to tell you this other thing.
Right, and that's the problem. Even if you do avoid "cheating" and "I ran X miles so I deserve this" type things, your body will still mess with your metabolism to compensate for the added exercise, and that works against the weight loss plan.
I went from near-zero exercise to ~10 miles of running per week, and maintained that more or less for 2 years without experiencing any significant weight loss (it was/is definitely valuable for general cardiovascular health, though). Only changing my diet helped, and even then it was difficult to lose weight and keep it off (took a year to lose ~7 lbs, and less than half that to put them back one). But now with COVID-19 and sheltering in place, I've been cooking nearly every day, and in less than three months have lost 15 lbs, and I've been running less than usual.
But really, everyone's individual experience differs. It seems like nutrition and exercise advice really needs to be tailored to each person, and sometimes there's a bit of trial and error involved.
Still exercise may help so many other aspects like mood, energy,sleep quality etc. (even if not in the moment but with an hour or day or two delay) which are all helpful to keep oneself on track in the kitchen. It can be a concrete motivational goal to be able to lift this or that much, run so and so far, and it's straightforward to see how you will need to pay attention to your food it you want to achieve that.
> Still exercise may help so many other aspects like mood, energy,sleep quality etc. (even if not in the moment but with an hour or day or two delay) which are all helpful to keep oneself on track in the kitchen.
So, in other words, my initial statement is correct: you're not going to make meaningful progress weight-loss-wise without changing your diet. If exercising makes that easier for you as a second-order effect, that's great. But that's by no means universal.
I used to think this too, until I switched to a low carb diet. The raging fire in my belly, inability to concentrate and overall sluggishness just simply...disappeared.
That’s when I realized that “my body needs X to Y” is unhelpful unless you’ve experimented with lots of different values of X for long enough for your body to adapt.
I’m not saying you haven’t, but I’m just reiterating the importance of tinkering with your approach to diet and exercise. By the time we reach adulthood, our bodies have adapted to years of bad eating habits. Reshaping the hormonal and microbiotic responses may take a few weeks of discomfort/unusual response before seeing results.
A lot of what I've read over the past few years suggests that exercise won't help you lose weight[0]. It's great for general health, but exercise without some kind of diet modification generally won't do all that much for your weight.
This tracks with my experience, at least. In early 2016 my doc told me I needed to get some exercise. At the time I was doing nothing more than walking to and from work (60 mins total). I started running, and worked up to around 10 miles per week. I'd already been more or less been doing IF for a while (without realizing it; I was just never hungry when I woke up), eating lunch at noon and dinner at 7pm, or just a single mid-afternoon meal around 3pm.
I didn't start actually losing weight until 2 years later, when I started calorie counting and attempting to limit my intake to around 1500 per day (I wasn't always successful). It was still difficult; I only lost 6 or 7 lbs, and it took nearly a year to do that.
That turned out to be hard to maintain; I stopped counting calories, and by late 2019 I'd put those lbs back on and probably a couple more, even with IF in place.
With COVID-19, I've been cooking 6 days a week, so that's meant less oil/butter, nothing fried, but still a good amount of carbs. My running has dropped to 4-6 miles a week. But in less than three months, I've lost 15 lbs. The only thing that actually worked was changing my diet. Once things go back to normal and I'm going out to restaurants again, I fully expect I'll put that weight back on.
[0] E.g. https://www.vox.com/2016/4/28/11518804/weight-loss-exercise-...
Another part of the story is showing the feedback cycles between glucose, insulin, and insulin resistance. I made a line art drawing as a gist, here:
https://gist.github.com/xpe/8d5c6243fba454e5987e87e9bc461a58
I already pasted it into another comment, so I don't want to exceed my line art threshold here.
Many people who do intermittent fasting go without eating from, say, 8 pm to noon the next day (16 hours). If you sleep between ~10 pm and ~6 am, in my experience, you might have a little bit of hunger at some points in the morning, but you can get used to it. I typically felt great on days I did it.
Do you have a medical condition? that's a lot of calories to take on for Breakfast, that's almost half my daily quota.
Two bowls of cereals can fly very quickly into one’s belly, pour in some milk and the tally easily crosses the 1000kcal mark.