If ultra low calorie diets don't work, why does WLS work?
Dieters hear over and over again not to go under 1200 calories a day. We are told that doing so will backfire, slow down our metabolisms and be counterproductive.
If the above is true, it would seem that small pouches or tight bands would be counterproductive. Why is WLS so successful, but dieting fails?
Can WLS slow your metabolism just like a low calorie diet? If so, does that create challenges in maintenance? Or does WLSers avoid metabolism slow down due to eat small frequent meals?
(btw...i'm not trying to make any kind of argument here-just trying to learn and understand things as I research WLS as an option!)
Thanks for sharing you experience and opinions with me!!!
You can slow your metabolism, but you cannot stop it. There's a good deal of evidence that wls does slow metabolism. Most of the studies of success rates put wls surgery at around 50% or less (and success is defined as any weight loss maintained), which means that half of wls patients gain all of the weight back or more.
For bypass operations, this should be theoretically impossible unless people are not only returning to old habits, but exceeding their "old" caloric intake (if part of your digestive tract is removed, you should be able to lose some weight with no behavior change at all - but that doesn't seem to be what happens).
Very low calorie diets work too - but usually in the short run. You can starve yourself to death (again, because you can slow metabolism, but you can't stop it), so it's theoretically possible to crash diet to your ideal weight. I say theoretically, because the success stats are pretty poor. I suspect because it's very difficult to sustain vlc diets for physiological and psychological reasons (WLS addresses some of those issues - such as hunger and appetite. Also, the wls, at least in the beginning, makes overeating extremely uncomfortable or even painful).
You can acheive exactly the same results of lap band surgery with calorie restriction (as long as the calorie intake is the same). Of course, without the surgery, you'll have to do it with a lot more hunger.
However, it's unlikely that you can acheive the same results with diet alone as with surgeries that bypass or remove part of the digestive tract. You're now changing how much food is absorbed. If metabolism weren't effected, it should be virtually impossible for patients to gain weight after these surgeries - at least not without eating far more than they did before the surgery. Yet that's apparently not the case. Many who've gained some or all of the weight back say that they must eat far fewer calories to maintain weights that before the surgery required many more calories.
Wls is a tool, and it has some advantages over "diet alone." It also has some very significant disadvantages (lifelong risk of vitamin deficiency, with bypass surgeries, for example).
There is so much going on when you have WLS that it's not a clear-cut or straightforward answer. I can tell you right now that I've had WLS, and while my RMR has decreased along with my weight, it has not done so drastically. I participated in a clinical study at Johns Hopkins that followed WLS patients of the four main types of procedures (band, RNY, DS, and VSG), and one of the tests conducted was testing RMR. The last time I had that test done was 9 months after my surgery, and my RMR was still just over 2000. At a bit more than a year post-op, I can easily consume 2200 calories in a day, and that's when I'm restricting my carb intake.
Regarding success statistics, I have done quite a bit of research, and the success rates for WLS range from about 50% to 85%, depending on the procedure, and "success" is defined in the WLS community as losing at least 50% of your excess weight.
Jill - how cool that you are in a study! Not many of us can know our exact RMR. The success stats you state are what I have heard too.
I've never heard stats on what percent regain all weight. Kaplods, do you remember where you read or heard that 50% statistic? Based on stats I have heard, there could be a 50% "failure" rate, but that is with failure defined as not maintaining a weight loss of at least 50% of total lbs overweight at the time of WLS. If 50% are regaining ALL their weight, plus some, then that is a super scary stat to me!!
Great responses - thanks! This is a question that has bugged me for a while!
there's also some evidence that surgery - just about ANY of them - may affect the neuroendocrine signaling for appetite and digestive processes. the effects of these changes, let alone a complete catalog of them, are completely unclear. for right now, there's only some evidence that they change.
Jill - how cool that you are in a study! Not many of us can know our exact RMR. The success stats you state are what I have heard too.
I've never heard stats on what percent regain all weight. Kaplods, do you remember where you read or heard that 50% statistic? Based on stats I have heard, there could be a 50% "failure" rate, but that is with failure defined as not maintaining a weight loss of at least 50% of total lbs overweight at the time of WLS. If 50% are regaining ALL their weight, plus some, then that is a super scary stat to me!!
Great responses - thanks! This is a question that has bugged me for a while!
Unfortunately, I've found wls statistics to be less well defined and more difficult to analyze than other surgeries and medical procedures. Only recently have what I consider "good" studies been coming out (and the results are more promising, but not much long-term follow up yet, because many of the procedures are still too new).
I've not reviewed wls statistics for about 18 months to 2 years, so my information may be out of date. I had a heck of a time finding ANY solid research on numbers (or a consistent definition of success). Many surgeons count any weight loss maintained after 2 years as "success" (and it's in their best interest to do so, because they can literally say "I've never had a patient fail").
I'm actually very happy to hear that an objective standard seems to be emerging (50% of weight lost). That's marvelous.
One of the reasons (aside from increased risk factors) I determined wls wasn't for me, was the difficulty in finding hard data on success, failure, and post-surgery death rates. When I discovered that virtually no one was recording death rates post-surgery (more than 6 months out), it made me very nervous.
Since one of my risk factors is already a tendency towards vitamin and mineral deficiency (even with a balanced diet and vitamin/mineral supplementation), I was especially looking for information on long-term vitamin/mineral deficiencies of post-surgical patients - and the data just wasn't there. There were plenty of horror stories, but no hard data.
Since doctors couldn't tell me why I have the difficulty now, they couldn't tell me what it was likely to be afterward. To me, an unknown risk is not an acceptable risk.
I'm happy to hear that more specific data is coming out.
My surgeon told me that RNY gastric bypass surgery gives you malabsorption of calories. I think he was right... but then again, I rarely ate over 1000cal/day for the first year. I tried to keep each meal at around 300 or less and gave myself allowance for a snack in mid afternoon.
According to the metabolism test I took recently, I can eat 2000cal/day without gaining weight. I am trying to stick around 1500/day because I need to lose a bit more weight but don't want to do it too quickly. I'm wrinkled enough. I walk for 90 min/day also.
My surgeon told me that RNY gastric bypass surgery gives you malabsorption of calories. I think he was right... but then again, I rarely ate over 1000cal/day for the first year. I tried to keep each meal at around 300 or less and gave myself allowance for a snack in mid afternoon.
According to the metabolism test I took recently, I can eat 2000cal/day without gaining weight. I am trying to stick around 1500/day because I need to lose a bit more weight but don't want to do it too quickly. I'm wrinkled enough. I walk for 90 min/day also.
Congrats on your success - very impressive! It's reassuring to hear your metabolism is still burning 2000 a day!
If ultra low calorie diets don't work, why does WLS work?
Why is WLS so successful, but dieting fails? 
