Metabolic Rate and Weight Regain in Dieters

[tamarian]

Adaptive Metabolic Rate Changes Not Responsible For Weight Regain in Dieters
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WESTPORT, CT (Reuters Health) Nov 8 - Resting metabolic rate, which declines during periods of energy restriction, returns to pre-weight loss values once energy balance is restored, according to results of a recent clinical trial. These findings do not support the set-point theory of metabolic regulation as the reason for the tendency of obesity-prone persons to regain weight following weight reduction.

Dr. Roland L. Weinsier, of the University of Alabama at Birmingham, and associates studied 24 overweight women with body mass index (BMI) between 25 kg/meter squared and 30 kg/meter squared and with a family history of overweight, as well as 24 never-overweight control subjects. The investigators describe their findings in the November issue of the American Journal of Clinical Nutrition.

The investigators measured the subjects' resting metabolic rate and the ratio of serum triiodothyronine (T3) to reverse triiodothyronine (rT3) during the period of the study. The overweight women maintained an energy-restricted diet — 3350 kJ per day — until they lost at least 10 kg and reached a BMI of less than 25.

Resting metabolic rate and T3:rT3 fell within 10 days of beginning the restricted diet and remained depressed until the women resumed an energy balance diet. Ten days later, the resting metabolic rate and T3:rT3 values had returned to levels observed before going on the diet, neither value of which was significantly different from that of control subjects.

After approximately 4 years of follow-up, the overweight women regained an average of 87% of the weight they had lost while dieting. The researchers observed no trend for greater weight regain among women with a lower resting metabolic rate.

Dr. Weinsier's group writes, "If metabolic measures are obtained in weight-reduced individuals before energy balance is fully restored, results would give the misleading impression that weight-reduced persons are hypometabolic and prone to weight regain."

They further note that thyroid concentrations may be of use in documenting that patients have returned to an energy-balanced state following weight loss.

The investigators conclude that energy restriction, rather than weight reduction, is associated with a relative hypothyroid state and a reduced resting metabolic rate.

Am J Clin Nutr 2000;72:1088-1094.

[r.mines]

Wow! It sounds interesting, but can someone translate into English, please?

What I got out of it was, very roughly, that regain of weight in women on a calorie-restricted diet is NOT due to their metabolic rate being "reset" to a lower level during dieting, since metabolic rate returns to pre-diet levels about 10 days after "the diet" is over and a "normal diet" is resumed. So this is evidence against the "set point" theory. Which is a Good Thing for us!

But most of the women regained the weight lost (no surprise there). It'd be interesting to know why. Any ideas?

Rachel

[tamarian]

I got two points of this:

1. The set-point theory is still challanged (nothing new)

2. Low-calories slows the metabolism (nothing new, but further emphasized as the cause for regain when energy is restored to "normal"). In other words, if it's not a way of life (WOL), it won't work.

Wa'il

[doreen T]

This reconfirms your earlier Research post thread, about "Being Obese is not Destiny". Also, we had an earlier discussion on the NAASO study, and other research that showed other things were more likely to influence weight regain after dieting. Here's my quote:

.....went back through the archives of NAASO; from July '99, a study they published re "Predictions of Weight Loss Maintenance" ........The greatest factors for predicting lack of success at maintaining weight loss, were #1) frequency of previous dieting attempts, ie, chronic yo-yo dieters were least successful, also earlier age of beginning the diet-then-gain-cycle. #2) family history of obesity. #3) change in BMR, ie lowered metabolic rate due to chronic dieting or other health factors. #4) personal hunger score, ie, did the diet not provide satiety for the client?

We see the possibility of lowered BMR due to chronic yo-yo dieting, but many other factors as well. And as I recall, the study showed no difference between lowcarb vs. lowfat diets, ie, lowcarb dieters were no more likely to regain than any other group.

My take is that no matter what method works for an individual to lose the weight, returning to previous high-processed carb, high-processed fat eating will pack the pounds back on and them some. I agree with Wa'il, that any change to one's diet and WOL needs to be permanent. Lowcarb just happens to be more in sync. with how are bodies were designed to be healthy in the first place.

Doreen