Fasting, metabolism, and weight loss?

October 4, 2008 1:59 PM

Fasting, metabolism, and weight loss?

I am a relatively healthy 25 year old male, but for various reasons, I haven’t been eating properly lately (read: too much junk food), I have been drinking too much, and have recently started smoking. I have the next two weeks for myself, so I won’t be engaging in much activity besides reading, sending out applications, and hanging out with friends. I’d like to use at least part of this time to engage in an extended water fast in the hopes that the denial will help me bring my life more under control, and make me a healthier person in general. I fasted once before (though only for four days), and it was an incredibly positive experience, and not only did I not really notice the lack of energy, but I was a much happier person. As well as helping me find my lost discipline, and perhaps helping me to become a more spiritual person, I would also be doing this to this, hopefully, to lose a bit of a weight. I’ve done a fair bit of reading on the subject already, and have searched through previous askmefi questions, but there are a few issues that I remain fuzzy on:

What would be the ideal duration for such a fast without running into health problems? Ideally, I would like it to be somewhere between 5-10 days. I am open to suggestions that it be longer, but anything less than 5 days likely wouldn’t feel like enough to me.

What should I eat/do right before starting the fast, and when I break it?

I understand that when a person starts to fast the body turns to fat stores first, and then eventually starts to eat muscle. I’m unclear at what point the body switches from using fat, to using muscle, and at what point if any the burning of muscle would accelerate in relation to the burning of fat. I’d appreciate it if someone could clarify that.

I realize that fasting lowers metabolism and is in some ways counter-productive for weight-loss. I’m not worried too much about a temporary drop in my metabolism, as normally I get a fair amount of exercise, eat well, and haven’t really had any problems with it in the past. However, I am concerned about the potential for a permanent or very long term decrease in metabolism due to fasting. Should I be concerned about this, or will my metabolism return to a good rate soon after I end the fast, assuming exercise and a good diet?

Finally, how long after ending the fast should I wait before starting light cardio? Interval cardio? Weight lifting?

Thanks.

posted by paradoxflow to health (11 comments total)

Define "fast". Will you be eating ANYTHING? Will you be drinking? Water, other fluids, what?

There is no quick and fast answer to when the body switches from burning fat to burning muscle for everyone. The easy answer is when your body goes into starvation mode: when your body says "hey...i'm not getting food, i better hold onto those fat reserves". When you get physically hungry, your body does that.

If this is a 4-5 day get healthy quick scheme, it won't work. What you might want to do is use the two weeks to EASE into the EXACT lifestyle you want to commit to. Not only would you come out of it not having to make any drastic changes, but you will already be reaping the benefits after the 2 weeks, thereby reinforcing your will to stick to it.

Good luck!
posted by hal_c_on at 2:23 PM on October 4

Fasting is not the best approach for you. Instead, consider benign ketosis (such as the Atkins diet or similar diets): very little fast carbs, but enough protein, vitamins and essential fats to keep you healty and avoid loss of muscle mass. Benign ketosis is exactly the process you're describing: the body starts burning it's own stored fat. It takes about 3-4 days without carbs for the ketosis to kick in.

Btw, six months ago I started on a low carb diet and went into ketosis for about two months. I also started excercising (cycling/spinning, running and weight lifting). During this period, I've lost 17 kilos (37,5 pounds), but gained muscle mass. Best of all, once I started eating healthier and excercising, it was easier to continue than I had thought.

Good luck!
posted by iviken at 2:43 PM on October 4 [1 favorite]

I agree with hal_c_on. Lasting weight loss will not likely result from a fast. And it really depends on what kind of fast you are doing. I don't recommend an all-out no food fast, actually, especially for a 25 year old male. Perhaps a soup fast (low- to no sodium soups, organic preferable) or a juice fast (no high-fructose corn syrup or a lot of sugar - I like just lemon juice, maple syrup, a bit of salt, and water mixed together). Or just try eating very well, decreasing your portions, and exercising more. You said you had been eating junk food lately but that generally you eat well. One fast will not decrease your metabolism permanently but get ready: it's coming soon, that late-20s metabolism slow-down and to prepare for that you should eat well and exercise. (Broken record. Sorry.)

Ultimately, the effects of a fast depend on lifestyle and body type, and I doubt that anyone here can give you solid answers for your questions. I am a 29 year old female who can't fast for more than a day, and I haven't fasted in about eight years (no longer that good Catholic that I sorta was once).

Ultimately, I recommend decreasing your caloric intake a bit (if you are consuming 2700 a day, get it down to 2000 or 1800) and do more cardio. Quit smoking, drink in moderation, and avoid the junk food. (Try almonds and cranberries; you can train yourself to enjoy healthier munchies.) Hal_c_on seems to be right on: if you use two weeks to ease into a healthy lifestyle, it will become habit and all of the sudden you'll look back on your junk food, smoking ways and think, dude! Glad I'm not doing THAT anymore. Just fasting and expecting an easy change will be tough.

Good luck whatever you decide.
posted by cachondeo45 at 2:48 PM on October 4

Oddly enough, I just read a blurb in The Week about a 52 year old woman named Dawn Page who was put on a diet called "the Amazing Hydration diet" by her "nutritional therapist and life coach". According to the article, after several days of "eating little and drinking large amounts of water", she had a grand mal seizure due to a salt/water imbalance in her body, and suffered permanent brain damage.

Since you don't offer details, I don't know if this is the sort of thing you are planning. I am unaware of any proven health benefits of fasting, although I can understand how it might confer the psychological benefit of feeling in control. Probably consulting a doctor would be a good way to start.
posted by MsElaineous at 2:57 PM on October 4

There have been a few studies with mice, rats and humans that show alternate day fasting to increase health and longevity, and reduce weight, even though they're eating the same number of total calories on the second day. This is also reflected in some of the Weight Watchers forums I dipped into a couple of years ago. Lots of people on WW find that they plateau, but that an alternate day approach works for them very well in terms of healthy weight loss and vitality. I'm not a huge expert on fasting--I've done it 2-3 times over the past 10 years--but this alternating approach seemed sensible and effective.
posted by cocoagirl at 3:18 PM on October 4

although I can understand how it might confer the psychological benefit of feeling in control

That theory works out so well for anorexics ;)

If you feel you need to starve yourself to get control of your life you really need to see a therapist.
posted by missmagenta at 3:24 PM on October 4

Don't fast! Your body is already starving, not getting all of the nutrients and vitamins and good stuff it needs. You have been eating empty calories!

Instead, consider doing a JUICE FEAST! These guys are experts and have coached plenty of people through it. But best of all, they give you the run down for free on their web-site. Everything you need.

Juice feasting will help to rebuild your body and you will be getting all of the good stuff you need to clean out and rebuild. You can do it for a weekend, you can do it for three months.
posted by dhammala at 3:41 PM on October 4

I should have made this clearer, but I want to do this mainly for the spiritual/purification element of self-denial and it will likely be accompanied by a good amount of meditation. And if you can't separate that from "need[ing] to starve yourself to get control of your life" then please, don't offer your opinion.

It would be a water only fast. The issues concerning metabolism and weightloss were more a matter of curiosity than anything else, and the main question I wanted an answer for was how to start/end it in a healthy way, and what a reasonable length of time would be. I appreciate the suggestions, but if weight loss was my main concern I would skip the fasting and simply start eating better and hit the gym.

Though, from the answers so far, I think my expectations for how long it should last were way off, and now I'm thinking more like 3-5 days.
posted by paradoxflow at 3:58 PM on October 4

I fasted for 10 days quite successfully - although I drank water, lemon juice spiked with cayenne pepper and peppermint tea during it.

It was an interesting experiment and I felt pretty good after I did it. I was surprised I managed it actually. I didn't notice any ill affects from doing it afterwards.

What it did do was make me think a lot about nutrition and how my body works - and it did help to get me onto a better pattern of eating after the few days post-fast which I ate lightly and lots of soups.

I didn't notice any particular weightloss during it - and it wasn't about that as much as showing myself I have the willpower to resist eating too much food that is not good for me.
posted by gomichild at 5:39 PM on October 4

I should have made this clearer, but I want to do this mainly for the spiritual/purification element of self-denial and it will likely be accompanied by a good amount of meditation. And if you can't separate that from "need[ing] to starve yourself to get control of your life" then please, don't offer your opinion.

This seems to come up over and over again in metafilter threads, but I think it bears being said that many, many anorexics start out as very normal people attempting to diet or fast. To those who have seen friends go down this road, a statement that you're planning on "engag[ing] in an extended water fast in the hopes that the denial will help me bring my life more under control" is troubling. While a fast might give you a temporary feeling of control, a much more responsible way to do this would be through making small lifestyle changes--quitting smoking, cutting back on drinking, eating less junk food. Not only will this take greater discipline, but it's much more likely to make lasting changes to both your life and your body. You should certainly not need to deny yourself food--integral fuel for your body--in order to feel "much happier," and control issues like those definitely remind me of close friends who struggled for years with eating disorders. This may not be the case for you, but I think you should know why this sends red flags up to me, to people like missmagenta, and perhaps to others--especially since this is being done under the nebulous flag of spirituality. A ten day water fast is much, much longer than what's prescribed in many religions.
posted by PhoBWanKenobi at 5:45 PM on October 4 [5 favorites]

I once dropped 10kg in a week by kick-starting a weight loss program with a water-only fast (starting weight was around 120kg, if I remember right). 5kg came straight back the following week, and I my weight then plateaued for three solid months.

Fasting for a week or two is a really interesting experience, and at 25 you'll easily get away with it metabolism-wise. But don't do it in order to lose weight, because it will retard your progress.
posted by flabdablet at 12:59 AM on October 5