One of the things I’ve been very interested in lately is something that many people have termed metabolic damage.  Basically, this is the idea that by eating VERY low calorie diets (VLCD), a person can end up DESTROYING his/her metabolism.  This has become of interest to me particularly after competing in my figure show back in August.  After the competition (during which time I was on a relatively VLCD), I gained A LOT of weight back, VERY rapidly.  Not only this, but once I started to try and diet again, it seemed that NO MATTER WHAT I tried, nothing was working.  So, like any good Smart Fit Chick would do, I dug into the research to try and investigate whether this whole idea of “metabolic damage” was a real concept, or something I was using as an excuse for my weight gain.

One of the seminal experiments in the field of exercise physiology was conducted during WWII by an investigator by the name of Ansel Keys.  This study, now referred to as the “Minnesota Starvation Experiment” examined the physiological and psychological effects of prolonged, severe dietary restriction.  The purpose was to investigate various refeed methods, in order to come up with the best strategy for those returning from war, who would be extremely undernourished upon their return.  The effects that this dietary restriction had on individuals both physically and mentally, are extreme.  Now, while there may be important differences between this study and a typical extremely low calorie diet  (e.g., all the participants in the study were men), the effects are still quite translatable to other populations.

So why do I think that these studies are relevant for our followers?  As females, it’s incredibly common for us to chronically underfeed ourselves.  Kellie and I see it all the time… Normal weight women are trying to lose weight by restricting calories, often eating anywhere from 800-1200 calories per day.  Another prime example- anyone familiar with the HCG diet?  That one requires followers to eat 500 calories per day.  The effects of these diets can be catastrophic, and it’s important to know this so that you can avoid this metabolic damage.  One VERY important point I want to make here, is that the individuals in this study started in the normal weight range.  So, these results are not generalizable to overweight/obese individuals.  However, a great topic to cover next would be VLCD for overweight/obese individuals.

So, on to the interesting stuff… the RESULTS! (Science can be SO fascinating sometimes!)  The dietary restriction lasted a total of 24 weeks (approximately 6 months).  Participants in the study went from eating ~3,200 calories per day (to maintain their weight), down to about 1,800.  Percentage-wise, they were eating a little over half of their daily requirement (56%).  Importantly, the researchers’ goal was to get subjects to lose approximately 2.5 lbs./week (not unlike the weekly goals we set for ourselves of 1-2 lbs/week).  Women tend to have lower caloric requirements than men, but very similar percentages are seen in VLCD.  For example, let’s say a female’s maintenance calories are 2,000 per day: 56% of that is 1,120 calories (not unlike many examples we’ve seen).  Ok, so what did researchers find after 6 months of severe dietary restriction?

1.  Physiological effects-

A. Every participant hit a weight loss plateau toward the latter part of the study… in fact, the weight loss looked somewhat like this (with time along the x axis (bottom) and weight loss along the y axis (side)):

Basically, as the study progressed, the amount of weight these individuals lost gradually plateaued, even though the amount of food they were eating either stayed the same, or in some cases decreased to try and force weight loss.  Importantly, this was a very well-controlled trial.  Subjects were housed and given meals all in the same vicinity, so there was little ability for subjects to “cheat” on their diets.

B.  After the weight loss period, a 12-week controlled weight regain period was initiated whereby researchers gradually increased calories.  In the majority of subjects, a higher proportion of fat was regained compared to lean tissue (e.g., muscle), regardless of the composition of the diet.  This higher fat regain was attributed to decreases in thermogenesis, or the body’s heat regulatory system (think “burning calories”), which is controlled by the thyroid hormone and the sympathetic nervous system.  After the controlled refeed, which lasted 3 months, NONE of the subjects reported being fully recovered, and the story gets even worse.  When subjects were no longer required to be on the research diet, the fat regain for most of the individuals was astonishing.  Most ended up gaining much more fat than they initially had before weight loss began.   Subjects reported that it took up to an additional 2 years before their metabolisms seemed to be back to normal.  Long story short, this extreme dietary restriction screwed their bodies up big time!

C. Multiple other physiological side effects were noted during the dietary restriction, including lack of sex drive, dizziness, extreme fatigue, muscle soreness, hair loss, skin changes, anemia, ringing in their ears and reduced coordination and other neurological deficits.  Many of these individuals had to drop out of school because they were unable to concentrate and perform well.

Now, while these physiological symptoms may sound bad, the psychological effects of the dieting was even more shocking.

2.  Psychological- Subjects reported increased irritability and impatience with those around them.  They became completely obsessed with food, focusing solely on when the next time they would eat, and what they would be able to eat.  Two subjects suffered severe psychological distress during the dietary restriction period, resulting in brief stays in the psychiatric ward of the university hospital.  Subjects became quite introverted, avoiding much interaction with other individuals.  Finally, depression and anxiety ran rampant through these subjects during the course of the study.  (It’s important to note that all subjects underwent intense psychological evaluation prior to being enrolled in the study so as to avoid enrolling individuals who already struggled with depression, anxiety, etc.)

So, why is this important?  It’s important because we see SO MANY individuals who are not severely overweight start dieting.  We see advertisements all the time for fad diets, including the HCG diet.  Many of us are probably underfed as we speak.  Do you know how many calories you eat per day?  If not, I’d suggest you track them for a few days (myfitnesspal works great for this).  Be sure that you’re not chronically underfeeding your body, because the mental and physical health effects can be devastating.  And for those of you who think you may have already done some damage to your metabolism, stay tuned for a future post on how to recover it.

Stay Smart:)