NY Times - Study Shows Why It’s Hard to Keep Weight Off

fgummett · 11-08-2011, 12:42

NY Times - Study Shows Why It’s Hard to Keep Weight Off...

Quote:

For years, studies of obesity have found that soon after fat people lost weight, their metabolism slowed and they experienced hormonal changes that increased their appetites. Scientists hypothesized that these biological changes could explain why most obese dieters quickly gained back much of what they had so painfully lost.

But now a group of Australian researchers have taken those investigations a step further to see if the changes persist over a longer time frame. They recruited healthy people who were either overweight or obese and put them on a highly restricted diet that led them to lose at least 10 percent of their body weight. They then kept them on a diet to maintain that weight loss. A year later, the researchers found that the participants’ metabolism and hormone levels had not returned to the levels before the study started.

The study, being published Thursday in The New England Journal of Medicine, is small and far from perfect, but confirms their convictions about why it is so hard to lose weight and keep it off, say obesity researchers who were not involved the study.

They cautioned that the study had only 50 subjects, and 16 of them quit or did not lose the required 10 percent of body weight. And while the hormones studied have a logical connection with weight gain, the researchers did not show that the hormones were causing the subjects to gain back their weight.

Nonetheless, said Dr. Rudolph Leibel, an obesity researcher at Columbia, while it is no surprise that hormone levels changed shortly after the participants lost weight, “what is impressive is that these changes don’t go away.”

Dr. Stephen Bloom, an obesity researcher at Hammersmith Hospital in London, said the study needed to be repeated under more rigorous conditions, but added, “It is showing something I believe in deeply — it is very hard to lose weight.” And the reason, he said, is that “your hormones work against you.”

In the study, Joseph Proietto and his colleagues at the University of Melbourne recruited people who weighed an average of 209 pounds. At the start of the study, his team measured the participants’ hormone levels and assessed their hunger and appetites after they ate a boiled egg, toast, margarine, orange juice and crackers for breakfast. The dieters then spent 10 weeks on a very low calorie regimen of 500 to 550 calories a day intended to makes them lose 10 percent of their body weight. In fact, their weight loss averaged 14 percent, or 29 pounds. As expected, their hormone levels changed in a way that increased their appetites, and indeed they were hungrier than when they started the study.

They were then given diets intended to maintain their weight loss. A year after the subjects had lost the weight, the researchers repeated their measurements. The subjects were gaining the weight back despite the maintenance diet — on average, gaining back half of what they had lost — and the hormone levels offered a possible explanation.

One hormone, leptin, which tells the brain how much body fat is present, fell by two-thirds immediately after the subjects lost weight. When leptin falls, appetite increases and metabolism slows. A year after the weight loss diet, leptin levels were still one-third lower than they were at the start of the study, and leptin levels increased as subjects regained their weight.

Other hormones that stimulate hunger, in particular ghrelin, whose levels increased, and peptide YY, whose levels decreased, were also changed a year later in a way that made the subjects’ appetites stronger than at the start of the study.

The results show, once again, Dr. Leibel said, that losing weight “is not a neutral event,” and that it is no accident that more than 90 percent of people who lose a lot of weight gain it back. “You are putting your body into a circumstance it will resist,” he said. “You are, in a sense, more metabolically normal when you are at a higher body weight.”

A solution might be to restore hormones to normal levels by giving drugs after dieters lose weight. But it is also possible, said Dr. Jules Hirsch of Rockefeller University, that researchers just do not know enough about obesity to prescribe solutions.

One thing is clear, he said: “A vast effort to persuade the public to change its habits just hasn’t prevented or cured obesity.”

“We need more knowledge,” Dr. Hirsch said. “Condemning the public for their uncontrollable hedonism and the food industry for its inequities just doesn’t seem to be turning the tide.”

Daytona · 11-08-2011, 13:17

The question of how to reduce leptin resistance and reset your hormonal balance is the big one in my opinion. Studies have shown multiple times that losing weight alone doesn't fix the leptin resistance and that testosterone, estrogen, insulin, leptin and greylin don't usually go back to the pre-overweight values.

Leptin especially (which they mention in the article) skyrockets in the obese and then plummets after significant weight loss often causing permanent stalls. Studies have tried injecting leptin, which does start weight loss again (and correct hunger, etc) but it's questionable that keeping leptin levels abnormally high is acceptable. The real treatment would be to correct the leptin resistance.

Chris Kresser, Stephen Guyenet, Jack Kruse and Ron Rosedal are the ones who immediately come to mind that have discussed in great length how to address the underlying imbalance through diet and lifestyle changes.

* Kresser and Guyenet through the food reward/palatability theory.
* Kruse through eating more protein (e.g. 50g/meal), strict meal timing/composition and changing habits based on if the sun is out, etc.
* Rosedal through restricting protein (e.g. 50g/day).

All of them also mostly recommend eliminating the same foods (wheat, grains, legumes, dairy, sugar) with minor differences on how low to go carbohydrate wise.

I'm not sure what the answer is, though my fingers are crossed that it's not the food reward theory!

fgummett · 11-08-2011, 13:23

Surely the answer is to lose excess fat mass in such a way that the body is not starved and therefore does not need to resort to these hormonal changes in an effort to retain equilibrium? LCHF works for me.

Here is Tom Naughton's take on this article - along with some disturbing developments in health insurance... Higher Insurance For Fat People?

Daytona · 11-08-2011, 13:38

My understanding is that even when the weight is lost in a more appropriate manner (e.g. LCHF), leptin drops no matter what because fat makes leptin and when you lose a significant amount of fat, you leptin decreases. However unless the leptin resistance (in the hypothalamus) is corrected too, you will continue to have abnormal leptin levels (compared to your body fat %).

Considering how many times I have heard from people doing atkins, paleo, primal, LCHF that eventually they stopped losing weight at a higher # than is preferred (I'm not talking 10 lbs), I think this is often a problem for people across many diets. I have heard that often it's when people lose about 20% of their body weight. I don't think it's a question of "you aren't doing the diet right", but instead that they reached a new equilibrium based on their hormones.

I am not disagreeing that anytime someone loses weight through sheer will power alone (i.e. very low calorie diets, especially when it's high carb low fat) they are setting themselves up for heartache as soon as they transition to a "maintenance" diet. I've been through that before (as most of us have) and it's clear that method of weight loss is the worst when it comes to keeping it off.

I'm just trying to bring up the idea that even for people following (in my opinion) better diets, the issue of leptin can still be a sticking point.

fgummett · 11-08-2011, 13:56

Dr Robert Lustig associates Leptin Resistance with chronically high insulin levels -- again suggesting that a diet which reduces the need for Insulin and reduces excess fat mass (thereby reducing Insulin Resistance) would be beneficial in this regard as well.

Yes I have experienced plateaus over the last 3+ years but each time I just stayed the course (I see no reason not to stay with LCHF for life) and every few months I see a few more pounds drop and then a new equilibrium established... almost as if my body is adjusting slowly and in steps, back closer to normal.

The Cause of Obesity - YouTube

Daytona · 11-09-2011, 01:36

I wish there was an insulin-meter so that I could test my non-fasting insulin levels. It's so hard to tell if it's just low for the fasting (~5) and high the rest of the time. I would love to be able to say with confidence, no I don't have high insulin levels but unfortunately I can't.

It's good to hear from someone who has stalled out for a significant period of time (not just a week or two) and was able to get it started again. I've been stalled and struggling to not gain since June. *sigh*

I need to watch this video! I found Sugar: The Bitter Truth to be very interesting so this should be good.