Very low calorie diets and metabolic damage

There was a thread that was deleted yesterday where the original poster was asking if it was okay to consume something like 800 calories per day. I'm not sure exactly why it was removed, but it likely had something to do with person after person telling the OP that she was being stupid.

I don't like personal attacks at all... but what drove me even more crazy was the fact that almost every single person felt the need to chime in about a topic they obviously haven't studied very much. We heard things like your muscles are going to fall off, you're going to kill your metabolism, you're going to wind up in the hospital with nutrition deficit, you're being anorexic, etc.

I'm not posting this thread to restart all the flaming and trolling. I want this to shine a bit of objectivity on the subject of very low calorie diets and metabolism. I spent a decent amount of time explaining things in the thread that was deleted, so it was disheartening to see the information deleted. I think we can all agree that among other important goals, this community is about education.

As this thread in question is being discussed on my profile page, someone asked me to re-explain what I discussed in the removed thread. I'm simply going to copy and paste my response here:

Yes, very low calorie diets (VLCD) can reduce RMR and disrupt various components of the endocrine system. But correlation is not causation. Meaning... is it the VLCD or is it the effect of the VLCD that leads to the slowdown? Put differently, VLCD cause high rates of fat loss due to the massive energy deficits. Fat happens to be the home of the master hormone responsible for metabolic regulation - Leptin. Leptin lets out bodies know that it's fed. So if we have less fat, we have less Leptin. If we have less Leptin, we have less of a "fed" signal to the brain. If we have less of a fed signal, the body responds accordingly with the slowdown in RMR (and some other adaptations).

But the logical question you should be asking is, "Won't smaller or normal deficits also cause a loss in fat? And won't that loss in fat lead to the same sort of negative adaptations?" And the answer is yes. It's just that the VLCD will cause these adaptations to happen faster... but you'll also lose fat faster. Follow me?

This isn't an argument for people to start following VLCD as most will fail miserably. Once you factor in the psychology aspects of them, they're just not right for most long term fat loss plans. In addition, the lower your energy intake is, the more careful you have to be about nutritional adequacy. Meaning it becomes very easy to shortchange yourself of particular facets of nutrition, which can ultimately tap into "health."

For example, back in the day when the medical community was busy trying to fix obesity, they used VLCDs and weren't mindful of protein quality or quantity. Protein happens to support muscle mass. Sure, around here we're interested in preserving skeletal muscle, as that's what helps us get "toned," "lean," "athletic looking," "ripped," or whatever the cool buzzword is nowadays. But these experiments on the obese patients led to losses in other types of muscle... namely cardiac muscle, which plays an important role in being alive, obviously.

Point is, the more food you eat, the easier it is to cover all of your nutritional bases. You can still screw things up, but it's just harder.

In the thread that was deleted last night, I spoke of the Minnesota Starvation Experiment ran by Ancel Keys, which took already relatively lean men and locked them down in the lab where they were given 50% of their calorie needs for half of a year. They also had supervised exercise ever day if memory serves me correct. We know that lean people will react faster (in terms of metabolic slowdown) to big energy deficits than fat people will. Which makes sense.... fat bodies don't "think" they're starving as quickly since they have all of this excess energy in storage, right?

But even with the test subjects in this experiment being lean to start, after the 6 month period, they only experienced a slowdown in RMR of 15% or so. I mean total energy expenditure dropped by 40% or so, but the remaining 25% (above the 15%) was due to the loss in weight (tissue costs something to maintain and a bigger body is more expensive to move around). Everyone knows that as weight is lost, calorie needs go down.

The "starvation mode" totaled 15% after half a year of low calorie dieting. And that's the primary point... life requires energy expenditure. And metabolism can be thought of as our total energy expenditure in this case. Even if there is negative adaptation to low calorie dieting, metabolism can only drop so far... there's a minimum threshold that's required to keep your heart beating, to fuel respiration, power the brain, transport nutrients, digest food, etc, etc.

I also posted a few links to more current research.... one paper compared a 25% deficit to a 890 calorie intake. The low calorie intake lost more weight than the 25% group. Yes, they had a metabolic slowdown... but so did the 25% group, which corresponds to what I said above about big and small deficits.

There's a lot more that I could say on the topic. For example, NEAT (non-exercise activity thermogenesis) is turning out to play a substantial role in the reduction in total daily energy expenditure experienced on prolonged diets... big or small deficits. Which only stands to solidify the importance of exercise while dieting. NEAT drops unconsciously... so we counteract that by doing more activity consciously via structured exercise. But we won't dive into that end of things as this is already far too long.

The bottom line is this... VLCDs are not as destructive as people around here are making them out to be. People see VLCD and immediately think of anorexia. Anorexics lose weight past the point of healthy thresholds. They also aren't mindful of nutrition quality, more often than not. Not on low calorie diets are "unhealthy."

There's a time and a place where they may even make sense for some. I've used them. I've used them with some of my clients.

It's just that those times and places don't match beginners who obviously need to learn nutrition fundamentals before they go experimenting with advanced dieting techniques. If they jump right into very strict and limiting diets, there's a good chance they're going to wind up gaining weight, not because of some crazy adaptation that winds up creating stored energy (fat) out of thin air... but because they're not going to stick with it, and when they fall off the wagon, they fall hard and typically eat their faces off.

I'm not out there advocating VLCDs. Not at all... heck, I wrote the Nutrition 101 article, which everyone should have read by now, and nowhere in it did I advocate VLCD. I'm simply trying to maintain the integrity of information while steering people in an optimal direction. It seems like too many people around here are stuck on absolutes. They believe there is 100% right ways of doing things and 100% wrong ways of doing things. There's no in between. In reality, there are very few absolutes in the game of fat loss.