The claim: Yo-Yo Diets Slows Metabolism

The Claim: Repeated Dieting Slows Your Metabolism
By ANAHAD O'CONNOR

THE FACTS For years, experts have warned against yo-yo dieting, saying the practice of repeatedly losing and regaining weight slows metabolism and makes it harder to burn calories. Many dieters accept that as conventional wisdom.

The idea first gained ground in 1986, when a study found that rats that had been deprived of food would quickly regain the weight they had lost when they were allowed to eat again, even with fewer calories. Scientists concluded that the rats, after repeated bouts of starvation, were burning calories less efficiently, and hypothesized that the same effect would occur in chronic dieters.

Since then, half a dozen studies have examined the theory and failed to confirm it. One, published in The American Journal of Clinical Nutrition in 1992, looked at 50 overweight women who dieted frequently. It found no evidence that the women had either lower metabolic rates or smaller weight losses over time.

Still, Cathy Nonas, an obesity expert at North General Hospital in Harlem, said the myth was unlikely to die soon.

"We've debunked it many times," she said. "But it keeps cropping up."

THE BOTTOM LINE Yo-yo dieting will not alter your metabolism.

Thank you Scott...

It's so often repeated that "years of dieting killed their/my metabolism" that it's become a standard diet myth... sort of like the advice to "drink 8 glasses of water per day" as if deficit of water is the reason we can't drop weight (rather than the fact we are reaching for nuts and chips and cookies impulsively, instead of calorie-free glasses of water ).

It is quite self evident that when you restrict food intake metabolism does drop, but this is temporary. Our needs for energy are not 100% fixed, our bodies react and respond and adapt to environment. We are capable of conserving or using energy more liberally depending on the conditions of our diet and lifestyle. Just as the body will slow down metabolism "to survive famine" (aka weight-corrective diet), the body will kick it up again very rapidly during "to fully take advantage of feast" (aka weight maintenance or weight gain diet). The more you restrict or eat, the more extreme the body will go in its conservation of energy or usage of it. There's a lot of individual variation there; some bodies naturally conserve more, other bodies conserve less. Bodies that conserve more during restriction also tend to use less during feast, making weight gain easier. The converse is true with those who have a hard time putting on weight.

Still I think individual variation in metabolism is rather small (we are all human after all and so our energy needs are going to be much much more similar when age/sex/weight/height matched, than they are different, much like all individual human variation).
Most of this "post dieting wrecked metabolism" nonsense has to do with cyclical dieting causing psychological trauma that triggers or exacerbates dysfunctional and abnormal diet and lifestyle patterns. It is this behavior that causes fat gain, not a wrecked metabolism. An inability to "control yourself" around "bad" food, all food, strange eating schedules (eating nothing all day then binging), strange eating habits (compulsively all day) can all be triggered or made worse by the psychological trauma of dieting.
Furthermore, if there exists a genetic tendency toward insulin resistance, post-dieting dysfunctional eating could trigger the insulin resistance which brings new problems that for physiological reasons also lead to dysfunctional eating, food obsession, and weight gain. In that famous study of starvation involving men, all adopted extremely abnormal post-restriction eating behaviors, all gorged themselves and gained weight. Almost all men weight and eating normalized after a period of time. However, a minority of those continued to gorge and gain weight even after they reached their old weights and well after restriction ended. My theory is that this minority of men triggered a susceptibility metabolic syndrome by the binging / compulsive eating behavior.


Anyway, I don't think it's possible for our bodies to "learn" to be more thrifty anymore than they can "learn" to be more liberal with energy. All you have are genes and environment, and these two can mix to produce either disease or health... states that are wholly reversible depending on the present mixture of genes and environment. You'll notice no one ever says "oh all that healthy eating "taught my body to burn more energy"". It's assumed that when metabolism increases in response to positive lifestyle changes, that the change is temporary and dependant only upon continuation of the diet and lifestyle that produced it. Why do we, then, feel that poor eating and lifestyle can "permanently lower metabolism"? Perhaps it's because we don't want to admit it's not so much the metabolism that's permanently lower, but our diet and lifestyle that's permanently unhealthy?

Another factor which fuels this myth is people compare their bodies when they were 17 to when they are 45. "I"m a 45 year old seasoned crash dieter, so I can't lose weight well like when I was 17". Is it the dieting, though, or is it simply age combined with a far less active lifestyle (and less active lifestyles usually mean more food consumption - it's easier to eat when you're sitting on the couch watching CSI vs going out with friends as a kid). I believe metabolism drops with age, and that is normal. Years of dieting did not kill your metabolism, aging did, and it's also very likely that your metabolism being slow has a lot more to do with your eating more and exercising less as an older person .

But that's all conjecture on my part.
All I can say with certainty is in my own experience, slowing of metabolism and speeding up of metabolism are dependent primarily on the quality, quantity, and nature of your diet and lifestyle. After two straight years of under eating to correct obesity and showing numerous symptoms of "starvation mode" my body rebounds almost instantly when I feed it more food. Please note I never binged or engaged in any extreme post diet dysfunctional eating; my extra food intake was slow and gradual and it came primarily from fat and protein. People who "refeed" by binging and gorging on carbs may see different results (as these are not healthful behaviors and tend to promote fat anabolism). In my personal experience with segueing from under eating to an isocaloric diet, scale weight gain has been insignificant, fat gain almost non-existent, mostly I've noticed much more energy and more muscle definition. I just look and feel healthier, rather than unhealthier (piling on fat weight and feeling tired).

I never had a position on this, but I'd often heard it claimed. It's been outside my experience since the low carb diet I started in late 2003 is the first I'd been on that lasted more than a couple of months. I never yo-yo'd, because I never really lost any weight for most of my life.

People obviously believe that losting/gaining/losing/gaining in loops has damaged their metabolisms, but there apparently isn't much in the way of proof of it. I suspect it may have been that we yo-yo becuase we choose unsustainable liquid, low fat, or calorie restriction diets.

I know there are no stats out there on the relative amount of loss/gain cycles on low carb vs. other diets, but my experience is that the cycle is broken by a much easier to sustain way of eating rather than broken by metabolic issues that may be mroe the result of aging and a changing body than up & down weights.

That said, I doubt loss/gain is good for you. But I'm not sure it's any worse than the gain/gain process I went through most of my life.

Well..... I have yo-yo'ed more times than I care to admit to I pray that this will be my last time!! I'd have a hefty resume if I wrote down all the different diets I've been on over the years since I was a teenager. Yikes!!

I think that my age has been the biggest factor in my metabolism this time. I just turned 55 this past week and menopause is playing havoc with my body.

No excuses!! Just stating facts!!

So ....Thanks Scott!! Its good to know that my yo-yo'ing isn't the reason I'm losing slowly!!

I think some of the factors that contribute to the slowdown of metabolism are homeostasis and loss of muscle/lean body mass. It is true that chronic or long-term dieting can downregulate the thyroid, and low-carb doubly so due to its effects on the liver. The thyroid is the main controller of the body's metabolism, so when the body senses that it is not getting enough nourishment (I think in the hypothalamus), it will produce less T4 and/or T3.

From personal experience, chronic dieting will definitely lower metabolism. I had been pretty much dieting for three years straight and for the past two or so I did not lose any weight, felt cold and miserable all the time, and had secondary amenorrhea. After eating maintenance for about two weeks, I can say that my metabolism is back to normal, or as "normal" as it's gonna get. Ah, it's hard being an endomorph

Loss of LBM will also lower metabolism, though I don't think I need to explain this to anyone

Well, this is good news for me. I'm planning on trying a few days a week of a PSMF (protein sparing modified fast) to see if I can get some of this weight to budge. I'm just doing a few days at a time so my metabolism doesn't adjust too much. Then I'll go back to my regular low carb diet.

My take on this:

Sorry, Judy, but if we both apply for the chronic dieter job, I bet I'd get the position. I, too, have lost track of the number of diets I've attempted, esp. in my twenties and thirties.

In the last 4 months, during which I turned 50, I've lost 50 pounds. I know others have outpaced that loss, but frankly, I'll take it and run--I don't think I've ever lost faster. I think the significant factor for me is exercise. Also, though I have overeaten more than once, and ate when I didn't plan on eating, but I have stayed LC all the way.

When I first found this forum, there was a thread about the relative ease of losing weight in the first 5 to 8 months, after which results tanked. I decided then that I would take advantage of that window of opportunity, and go hell-bent for leather during this time. If and when I hit the wall, I may or may not interpret that as an indicator that I need to stabilize there for awhile, rather than fight for every tenth of a pound. Will keep y'all informed (like you can't wait, right? :lol

my .02 . . .

Aside from age, medication, thyroid conditions or disease. I always believed your basic metabolism generally stayed the same...Maybe it is true...maybe it is not but I know through years of ED that should have wrecked my metabolism...the basic calories or lack there of have caused the same gains and loses on the scale....except when I was on meds that hampered my weight loss....

L

I've always been suspicious of the damaged metabolism thing. I have no doubt that it happens in the short run, but that you can permanently wreck your metabolism through diet alone (I know of a meth addict who destroyed his metabolism through his drug habit) seems like it goes a bit far.

Still, the firm conclusion at the end of this article makes me uneasy. So far, research has failed to confirm the effect, but it doesn't seem as if they've done a whole lot of it -- six studies? Failing to confirm something does not necessarily establish its lack of existence.

I am sceptical of explanations which use age as a factor. Aging, by itself, does not necessarily cause anything. Insulin resistance increases over time. So the vast majority of people who do not eat low carb are slowly but surely increasing their insulin resistance. The higher the insulin resistance, the harder it is to lose weight.

Hmm... well, with aging a number of things seem to happen. Lots of hormones drop off, including thyroid. In my case, I wasn't creating as much T3 (the active thyroid hormone) as I should have been. It seems to happen quite frequently in middle-age and beyond. Obviously lots of changes happen as we age, thus women stop menstruating and so on. And hormones are probably the most important indicator of your metabolism and whether or not you tend to build muscle or store fat.

As I understand it is the leptin (brother of insulin) resistance
that makes it so hard to lose.. again yo-yo dieting increases
leptin resistance and hence makes weight loss harder.. IMHO

Kwikdriver, I have to agree. Had this been a study with 50 members that 'showed' low carb to be harmful, I doubt that so many would enthusiastically embrace it without question. A study with 50 participants is not a large enough study to accurately show anything, IMO.
What did that study use as a control? How many of the participants had repeatedly lost and then regained weight (as opposed to having a long history of dieting). How much weight was regained after each loss?
Be careful of accepting a 'study' at face value just because you happen to like the conclusion that the study reached.

I'm sure happy that we aren't in a competiton then!!

It seems reasonable to me, that if you repeatedly starve your body, it would respond by putting on more and more weight in the "times of plenty". Whether or not this is caused by a general slowdown in metabolism, or through reregulation of some other biochemical pathway, is an open question. But I think it is safe to say, that there is plenty of evidence that people who diet and then go off, often gain back more weight than they lost.

And I disagree with those who say that aging and body shape changes are dependent on carbs in diet. I think the loss of muscle and bone mass as you get older, certainly does have an effect on your metabolism. Being on a low carb diet isn't going to keep you from aging, and the effects of aging result in changes in metabolism and body shape.