How much should I worry about losing muscle (especially organ damage) from crash dieting?
May 11, 2012 6:03 PM   Subscribe

How much should I worry about losing muscle (especially organ damage) from crash dieting? Is this a real thing or a diet myth? And if real, what's the best way to avoid it while losing fat as fast as possible? How crashy does a crash diet have to be to be actually dangerous?

I know there are real, reasonable reasons for not crash-dieting, mostly related to unsustainability and setting the metabolism lower - but I want to try it anyway. I'm not too extremely worried about losing a little muscle if necessary, but of course I mostly want to lose fat, and I don't want any organ damage.

I read some old threads on here, and they all seem to suggest that low-carb is the best way to go. At the moment I'm doing fairly/kind of low carb... mostly raw, actually, so that's very low grain, but there's some fruit and not much protein involved. I'm happy eating the way I am now and have lost weight quickly in the first ten days, but I'm just curious about this whole organ damage idea, which I recently remembered was a thing. Do I need to switch from raw produce to meat?

I don't have much of a background in this topic, but I'm fine with relatively technical explanations where applicable.
posted by lgyre to Health & Fitness (19 answers total) 9 users marked this as a favorite
There are three parts to this. One is the number of calories. Two is diet components. Three is duration. Going too far with either can result in bad outcomes.

If you don't have enough protein in your diet and keep the calories ultra low for too long, you can sustain heart damage and even death.

You can go ahead and take in zero food, and only water with electrolytes. That's fasting. Limitation: duration. Further factor - energy expenditure. You can last without food much longer, if you are not expending energy through exercising, a lot of movement, having to keep warm etc.

Protein: going below about 0.8g of protein per kg of your body weight on a daily basis is suboptimal, and if you do it for too long, the outcome will not be good. However, you can do so for months if not years at slightly below before damage shows up. But if you cut it back too far, like say, 0.2 g per kg daily, damage will show much faster, especially if you engage in exercise.

Calories. Depends on your size whether you're a man or woman. But as a general rule of thumb, you are pushing it healthwise if you keep your daily intake below 800 cal/day. Again, factor in energy expenditure, such as exercise etc. You start entering a danger zone around 600 cal/day. Of course, this again depends on duration. If you go for weeks, exercising and taking in 600 cal daily or less, you'll eventually get the health problems anorectics get. For an average sized male, say, 5' 9", who exercises lightly/moderately, it is not safe to go for sustained periods of time on less than about 1200 cal a day. For a woman, 5' 6", don't go below 1000 cal a day for a prolonged time.

Exercising will preserve muscle function, within limits. What will happen, over a period of months on a very low calorie diet, is that your internal organs will shrink, though exercise will preserve your heart size unless you really go too low for too long, like I outlined above. Your bones will also thin. Organ shrinkage and bone loss in this scenario (low calorie, but not below safety levels as I outlined above) will not be a health negative, especially if you exercise - in fact it may be extremely health-promoting, as caloric restriction diets have shown for decades. The problem is when you go to anorectic levels at or below 600-800 cal a day. The lowest long-term sustainable calorie levels for average sized U.S. males/females is about 1200/1000 - but that's extremely tough, not just because of hunger, but because it's hard to pack those calories with enough micronutrients.

Executive summary: don't go below 600-800 cals a day for longer than a couple of weeks or so, and keep your protein intake not below about 0.8 g per kg of body weight, especially if exercising.
posted by VikingSword at 6:39 PM on May 11, 2012 [4 favorites]

Also, standard disclaimers: IANAD or nutritionist. The above is my best understanding of the science at the moment.
posted by VikingSword at 6:42 PM on May 11, 2012

I want to try it anyway

As a fat 50-year-old man with a history of yoyo weight and currently experiencing extreme difficulty in persuading inexorably ratcheting weight gain to turn into small but steady loss, my best advice is that you don't.

If making sustainable readjustments to your life to keep your body working healthily already seems unrealistic or unachievable, have a good long think about how it might seem after entrenching your present habits for another thirty years.

I think you will find that there are many more old fat people with a history of crash dieting than old thin ones.
posted by flabdablet at 7:38 PM on May 11, 2012 [7 favorites]

Lyle McDonald's Rapid Fat Loss seems to be the trendy thing right now, in the fitness/bodybuilding community. It's the supposedly "safe and sound way" to crash diet. I am not endorsing it. From what I hear it's physically and emotionally grueling.
posted by jclovebrew at 7:49 PM on May 11, 2012

I would argue in favor of going paleo or slow-carb (Tim Ferris's 4-Hour Body) if you want to lose weight/inches without losing muscle mass.

Doing a Whole 30, high fat, moderate to high protein, and low carb, seems to be a pretty safe way to lose weight and inches without losing muscle.

I have been doing something like an 80/20 primal diet for the past eight months or so and I don't think I've ever looked better, and according to my doctor, I'm in fantastic shape medically speaking, and I've "leaned out" like crazy.
posted by padraigin at 9:03 PM on May 11, 2012 [1 favorite]

I definitely suggest you add protein to your diet. If you're not eating carbs (even if you're eating a few carbs with the fruit) you'll still be burning plenty of fat. Your body needs protein, and you're likely to achieve serious weight loss even if you eat it - so eat it and stay strong!

Here are some links on why your body needs protein.

Your current diet (if it does not include meat or dairy) also puts you at risk for vitamin B12 deficiency.
posted by treehorn+bunny at 11:28 PM on May 11, 2012 [1 favorite]

My experience is that relatively slow weight loss works, but crash diets make you bounce back to a higher level than you started with. The usual recommendation for sensible weight loss is 1-2 pounds per week.

Losing muscle is part of setting your metabolism lower. Muscle mass burns calories even when idle, and more when you use it. Losing muscle means you burn fewer calories per day, which is part of why your weight tends to bounce back when you finish the crash diet.

I think that at anything under the 1-2 pounds per day limit you will be losing some muscle. I suspect that "organ damage" only takes place if you eat much less than that, or eat a very unbalanced diet.

In general, I wouldn't worry too much about carbs. Look at reducing overall calories first, then make sure you're getting enough protein, fibre and vitamins second.

Basically I'd advise you against a crash diet, but if you're doing it for just a few weeks I think the problem is that you'll bounce back to a higher weight later, rather than that you'll die or suffer permanent damage.

If you're planning on doing it for months, seriously don't do it, or at least consult your doctor first.
posted by TheophileEscargot at 11:59 PM on May 11, 2012 [1 favorite]

You need 70 grams of protein a day and about 500 calories. I was on a surgically induced crash diet and this is what I "ate." I think it would be impossible to maintain a true crash diet without the surgery part.
posted by wandering_not_lost at 12:18 AM on May 12, 2012

I did 8 weeks at 750kcal a day. It was no problem AT ALL physically, although it was very hard mentally.

I drank 3 250ml meal replacement shakes a day. These were the balanced ones which each have a third of your daily mineral/vitamins, not the cheap ones which are mostly carbs. These were 201kcal each. I took a generic multivitamin too. I also ate a handful of steamed broccoli and/or a handful of steamed shredded cabbage with lots of salt on it. Finally I drank more or less constantly, with fibre dissolved in the water. Add the kcals for the green veg and the fibre to the shakes and you're in the 750kcal ball park.

You stop being hungry after day 5. The hunger is easy. Boredom and lack of texture and eating "ritual" was harder for me. The green very helped a lot with that, and it also gives your bowls something to do. Which is important after week 2, or everything goes to hell.

The shakes contribute 3x17g (48g) of protein a day. I think this is enough. I used callipers and other body fat measurements and am confident I didn't loose too much lean mass.

I did very high resistance weight training on alternate days. 3 sets of 8 reps of 6 exercises. Each exercise was very near my limit for that exercise. I was able to keep this up for the full 8 weeks, didn't feel too tired at any point.

I started on 1st Dec and did the VLCD aspect (as described above) from 1st Jan, then I went onto a <7>
On 1st Dec I was diabetic and on course for a medicated future. I am still techinically diabetic (you can't be undiagnosed) but I "pass" all the tests today and don't take any medication.

So its all anecdotal, but my experience is that 750kcal/day is a LOT harder mentally and a LOT easier physically that people say. I didn't lose any strength that I've noticed. I stopped exercise (other than the weights) during the VLCD but had no problems picking back up my normal activities once I resumed eating.

Don't underestimate the mental aspect of not snacking or eating a meal for weeks on end. Especially if you live with other people. But physically the only real problem I had was low salt intake led to low blood volume which made me faint and dizzy. Adding lots of salt to my veg fixed that easily enough. The only symptom that I never found a workaround for was feeling extremely cold. Your blood capillaries near the skin shut-down when you reduce you're calorie intake and this makes you feel cold within yourself, in a way that adding jumpers or clothes is hard to combat. So I was cold for 2 months, with hindsight I should have done the diet in the summer.

I consulted my doctor throughout. She was happy for me to do this for 8 weeks. Between 8 and 12 weeks she would have wanted to put me on a prescribed fibre-type product for bowl health and have me monitor my blood pressure. She would not endorse me going beyond 12 weeks.

I as alluded to before - I did this because I was diabetic and there is a small amount of evidence that putting your body into a starvation mode will make it take fats out of organs (specifically the pancreas) in a way that is very hard to do with normal dieting. I seem to have radically improved my pancreas's function but it is early days. But what is undeniable is that I have lost a LOT of weight (and little lean mass) in a short period of time.
posted by samworm at 5:53 AM on May 12, 2012 [2 favorites]

Sorry, some parts of my response got mangled.

One paragraph should have roughly read -

I started on 1st Dec 2011 and then did the VLCD aspect (as described above) from 1st Jan 2012 for 8 weeks, then I went onto a "less than 75g/day carb" diet and have roughly maintained my weight (with a small loss) for approx a month now. I lost 28kg (62lbs) in total by doing this."

Also, 3x17g is 51g not 48g.

The rest of it more or less makes sense.
posted by samworm at 5:59 AM on May 12, 2012

I'm doing the Lyle McDonald Rapid Fat Loss right now. Day 4 of 12 (I'm an athlete, so I only do it for very short periods of time). You can buy the e-book and work out your requirements, but he notes that protein needs to be pretty high (at least 1g/pound lean body mass) and you need supplements. This will prevent any damage, as well as helping maintain muscle, etc.

When you say low-carb, but then say you eat fruit and hardly any protein, that makes me think you are still consuming LOTS of carbs. A medium piece of fruit is about 25 carbs by itself. Unless you are eating just fat, then I don't see how you aren't eating carbs. Low carb is about 5-10g a DAY -- the amount that will get you rapid weight loss (a lot of which will be water initially). Lots of people confuse going low/no grain or gluten-free with low-carb. Carbs are in everything (including meat), but if you eat beans, rice, starchy vegetables like carrots or beets or sweet potatoes, fruit, etc. you are ingesting a good amount of carbs. The only way not to do that is to eat mostly meat and green vegetables or to simply not eat. I'd choose the meat, personally.
posted by mrfuga0 at 9:42 AM on May 12, 2012

Also: it would be useful to know your stats. Gender, weight, amount you want to lose, how active you are, etc.
posted by mrfuga0 at 9:43 AM on May 12, 2012 [1 favorite]

number one, start eating more carbs.

When you cut back on carbs, your body turns to proteins to make energy - this is suboptimal, nevermind the fact that gluconeogenesis produces ketones which can have harmful effects on the body.

There is no easy magic bullet to weight loss - (i.e. "cut fat!" "cut carbs!" "paleo diet!", so poorly named, that diet).

Essentially these are all workarounds - "how can I eat as much as I want of something and still lose weight!"

The answer is that you cannot. If you aren't at least a little hungry most of the time, then you aren't losing weight. A TRUE paleolithic diet would be an animal product maybe once or twice a week (hey, those animals are hard to catch!) and the rest of your diet would consist of plants - tubers (e.g. potatoes), leaves and flowers, (e.g. lettuce, broccoli), fruits (e.g. ....fruits), nuts, etc. Things you could find around the ground in nature.

And speaking of catching animals and digging for tubers, you'd be spending a lot of your energy looking for more food. Now, it's been shown recently that activity doesn't actually play a role in losing weight - it's all in how many calories you take in - but activity plays a role in keeping it off.

....and oh, I think I'm finally seeing your real don't need to switch from raw produce to meat to keep your protein levels up. Nuts are nice sources of protein as are legumes (yum, edamame!). I believe soybeans are also what they call "whole" proteins - they have all the amino acids, which is not common in plants (but is common in meat). So adding soybeans to your diet (or continuing to eat them) will be fine.

However, my original point still stands - cutting out carbs will cause an unnecessary drain on your protein stores.
posted by Lt. Bunny Wigglesworth at 1:16 PM on May 12, 2012

(er, misspoke - proteins aren't stored which actually adds to the problem ....but if you take in 200% of the recommended protein level for the day, but 40% of that has to be converted to sugars - and harmful ketones - the remaining 60% will be flushed out of your system....which means that if tomorrow you take in 100% of your recommended protein level and 40% has to go to sugar production - and ketones - well, now you've really only taken in 60% of the proteins you need....)
posted by Lt. Bunny Wigglesworth at 1:20 PM on May 12, 2012

For science-based info on low-carb, high-fat eating, you might find this MD's blog interesting. He specifically addresses common misunderstandings re: the dangers of ketosis:

There is a lot of misinformation that gets bandied about by well-meaning laypeople, so it's helpful to cross-check opinions with facts if you really want to understand how your body works, and what might work for you, diet-wise.
posted by quivering_fantods at 12:17 AM on May 13, 2012 [1 favorite]

Sorry--missing link.
posted by quivering_fantods at 12:18 AM on May 13, 2012

I believe Lt. Bunny Wigglesworth is completely wrong about carbs. If you're eating a high-fat, low-carb diet, your body will burn your body's fat more than your body's protein.

I'd recommend cutting the fruit (replace with non-starchy vegetables) and upping the protein and fat. Try the ketogenic diet, which is a 65%/35%/10% (by calorie) ratio of fat to protein to carbs. Check out /r/keto. You can quickly drop 5-10 pounds of water weight and continue losing at a pretty good clip eating as much as you want. (Without the insulin your body produces in response to carbs, you naturally want to eat less, really.) Do resistance training rather than cardio.

If you eat less or do a lot of exercise without upping your intake, you'll lose even more quickly, but I can't guarantee you won't lose muscle.

Most people feel kind of shitty the first few days but better afterwards.
posted by callmejay at 10:41 AM on May 13, 2012

Personally, for exercise, I would not avoid cardio. Rather, I'd recommend circuit training.

The reason is that you want to preserve heart function - and that means cardio; people think that just weight workouts by themselves are enough - not true, it is entirely possible to have big muscles, and be in relatively poor cardio-vascular shape.

For the purposes of this diet, your goals are:

1) Preserve heart muscle

2) Preserve musculature

3) Not expend too many calories while exercising for (1) and (2).

The answer is circuit training, because it combines cardio and muscle workouts and is very calorie efficient. You get the same cardio fitness that you'd get from long cardio workouts, at a fraction of the calorie count that you'd expend on conventional cardio workouts such as f.ex. jogging. You want to expend as few calories exercising, because you are trying to keep your calorie intake as low as possible, so you have less to spare, including exercise and thermogenesis (i.e. you should make an effort to keep warm with clothing and turning up the thermostat instead of asking your body to generate heat).

How effective is circuit training? From the link above:

"Studies at Baylor University and The Cooper Institute show that circuit training is the most time efficient way to enhance cardiovascular fitness and muscle endurance. Studies show that circuit training helps women to achieve their goals and maintain them longer than other forms of exercise or diet.[3]
And research from Morgan and Anderson showed:
"Perhaps a most profound finding of this study, from a health perspective, is that this investigation clearly shows that performance of this circuit of exercises, at this level of intensity elicited oxygen consumption values (39% to 51.5% of VO2max) that meet established guidelines of the American College of Sports Medicine (ACSM) for the recommended intensity (40% to 85% of VO2maxR) of exercise for developing and maintaining cardio-respiratory fitness (Pollock et al., 1998). Thus, this circuit not only provides a suitable muscular fitness stimulus but also helps to meet ACSM cardiovascular guidelines and the newly published Dietary Guidelines for Americans 2005 for physical activity.[2]"
posted by VikingSword at 2:31 PM on May 13, 2012

I believe Lt. Bunny Wigglesworth is completely wrong about carbs. If you're eating a high-fat, low-carb diet, your body will burn your body's fat more than your body's protein.

Carbs are the main energy source of every cell. EVERY medical and biology text will tell you this. EVERY. SINGLE. ONE.

Crackpots (like atkins), however, will tell you fats and proteins are totes ok instead.

Igyre - never listen to someone who doesn't know the basic biology of a cell on how your body works. It is a path to poor health.

Try the ketogenic diet,

You mean the one that produces ketone bodies that wreck your body? (because your body is not supposed to run on proteins and fats)

Most people feel kind of shitty the first few days but better afterwards.

Most people feel shitty because your brain actually uses the majority of your body's glucose - a carbohydrate. So now when you cut down sharply on carbs your body is starving itself. It has a backup system - getting carbs/acetyl-CoA from proteins and fats, but it takes a while to kick in. After it kicks in things are still not good - your body will now produce energy as before (i.e. no further weight loss) but now it is also producing ketone bodies.

If you simply starved yourself for a day or two you're get the same effects weight-wise, but they'd actually be healthier because you wouldn't have those ketone bodies.
posted by Lt. Bunny Wigglesworth at 9:57 PM on July 8, 2012

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