Join Date: Jul 2005
Location: Bucks County, PA
Linda posted a link to the message below in another thread. I read & thought it was important enough to re-post here -
I attended a lecture this week given by Rudolph L. Leibel, head of Molecular Genetics at Columbia Medical School, titled Mechanisms For Body Weight Regulation. We’ve had several discussions here in Maintainers about hormones, weight regulation, and metabolic rates after losing weight and he answered some of our questions. I can’t say these were answers that I wanted to hear, but this is really important stuff, so bear with me and I’ll try to summarize.
The first part of the lecture was all about research into how our bodies regulate their weight. I don’t want to go into the science of it in detail – much of it was over my head! – but the overall picture is that we have a complex system of hormones that act on our brains which control appetite, metabolism, and fat storage. We’re born with certain genes that generate and control these hormones which are then affected by the environment in which we live. His research shows that obesity is about 60% a genetic predisposition with about 40% attributable to our toxic food environment (the way we eat and live today).
Here’s the deal – genetically, we obese (or formerly obese) are the survivors. We’re evolutionarily selected to live in times of famine, when food was scarce and we had to work hard to find it. Think prehistoric times, when dinner meant stalking a woolly mastodon for a week before you could kill and eat it. Then contrast that with how we live now, when dinner means picking up your cell phone and ordering pizza. Food today (often calorie dense) is readily available and requires virtually no work to get it. Our genes are evolutionarily adapted to hoard calories as fat and use them very efficiently. So this system works beautifully if you’re a caveman, but not so well if you work in an office cube.
What this means is that it’s easy for many of us to get fat – not news to most of us. It doesn’t mean that obesity is preordained or that it HAS to happen – that’s still determined by our environment, which boils down to what we eat and how we live.
The second part of the lecture was the reason why I was there – how do we apply this scientific knowledge to weight loss and maintenance? I’m going to break it down into key points -
It’s Calories In Versus Calories Out: He began the second portion of the lecture by citing the First Law Of Thermodynamics – in terms of obesity, it translates into Stored Body Fat = Food Intake – Energy Expenditure. We here at 3FC mean the same thing when we say that you have to eat less (food intake) and move more (energy expenditure) to lose fat. The science of weight loss all comes down to numbers of calories in and out. Forget all the pseudo-science diet books out there about what to eat and not eat – at the end of the day, it’s nothing but numbers and calories.
Dr. Leibel has a lab at Columbia Medical School where he locks in volunteers for up to 27 months and monitors food intake and energy expenditure. He has NEVER had a subject who hasn’t lost weight on a low-calorie diet. They may plateau for a while, which he says is the body replacing lost fat with water temporarily, but ALWAYS lose fat in the end. So he said that people who say that can’t lose weight despite only eating a tiny amount of calories are kidding themselves about their actual food intake. He says that this formula holds true for everyone - Stored Body Fat = Food Intake – Energy Expenditure.
Metabolisms: It takes 50 calories per kg of LBM to maintain the weight of both obese and normal people (people who have never been obese). It’s important to note that the metabolisms of the obese are identical to normal people. The ‘I’m fat because of my metabolism’ argument was shot down in his lab because he discovered that obese and normal people burn calories at exactly the same rate. Obese people are simply taking in – or burning fewer - calories than normal people and storing the excess as body fat.
Back to the equation Stored Body Fat = Food Intake – Energy Expenditure - the energy expenditure (I’m going to abbreviate it as EE) part is made up of three parts: resting energy expenditure, non-resting EE, and thermic (the digestion of food). Resting EE accounts for about 50 – 60% of the calories we burn in a day, thermic accounts for about 5%, and non-resting EE makes up the remainder. If we take in more energy (calories) than we expend, it’s stored in our bodies as protein, glycogen, and fat.
Our Bodies ARE Different!: This is the part that’s relevant to all of us maintainers. Like we’ve long suspected, our metabolisms ARE slower after we lose weight. Scientific research shows that we have to eat less and/or move more to sustain our weight losses.
Here’s the deal - it takes 50 calories per kg of LBM to maintain the body weight of either a normal or an obese person. BUT … it takes only 42 calories per kg of LBM to maintain the weight of a reduced obese person (doctors and researchers call those of us who were obese and are now a normal weight the reduced obese).
We ARE different! Dr. Leibel said that we reduced obese may LOOK normal on the outside but our bodies are very different on the inside. He said that, in order to maintain our weight, we reduced obese need to eat 15 - 20% fewer calories per day than a comparable person – same height, weight and gender etc – who never was obese.
Why? The difference in calorie needs comes ALL from changes in NON-resting energy expenditure. The resting rate is unchanged. But our muscle efficiency increases by 15% after weight loss, so we become more efficient in using energy in exercise and everyday activities. And so we burn fewer calories per pound than either a normal weight or an obese person. It’s completely measurable in a lab – all you have to do is put the reduced obese person on a stationary bike and measure energy expenditure. We aren’t going to burn as many calories as normal people do. In practical terms, it means that when you’re at the gym on a treadmill, the person next to you is going to be burning 15-20% more calories than you do even is she is exactly the same height, weight and age (so long as she never was fat). Wonderful, eh?
Leptin Levels: The scientific reason for this change in metabolic rates between normal and obese and reduced obese persons has to do with leptin levels (a hormone). If you google Leibel and leptin, you’ll find a lot of scientific articles about his research that explains it all much better than I can. Currently Dr, Leibel is experimenting with giving reduced obese small doses of leptin to restore its level to that of normal and obese people and it seems to reverse this metabolic slowdown. Unfortunately, it’s not anywhere close to being released as a treatment for weight maintenance (he emphasized that it wouldn’t help for weight loss; it only works for maintainers).
My Thoughts On What This Mean For Us Maintainers: Wow! This is the scientific validation of what I think many of us have long suspected and it’s a reason why it’s so hard to maintain a weight loss. Our own personal experiences and National Weight Control Registry statistics show that we have to eat fewer calories and/or exercise more than normal people in order to maintain our weight losses. Now we know that it’s a FACT and we know why – our non-resting EE slows down by 15 – 20%. Our metabolisms weren’t slower when we were obese but they are genuinely and measurably slower now that we’ve lost the weight. We’re fighting against our own bodies wanting to get fat again.
I went up to Dr. Leibel after the lecture (and waited while he talked to all the MDs and PhDs) and introduced myself by saying that I had a little bit of a different perspective on the issue. I told him that I was a member of the NWCR myself (he had discussed it), told him about our Maintainers group at 3FC, and said that we’re LIVING his research. One of the questions that I asked was - would this slowed down metabolism ever change? Would our bodies adapt to our new weights and our metabolisms ever return to normal? (I was thinking about our Karen here, who’s maintained her weight loss for 15 years) He said no, that the lowered leptin levels were permanent. It’s our bodies' way of trying to make us eat more and get fat again.
But he emphasized that it IS possible to maintain a large weight loss – it’s just a little harder for us to maintain our new normal weights than for people who never have been fat (again, not news to any of us). All these hormones and body weight regulations can be defeated by monitoring our calories in versus calories out because – remember - it’s all numbers. OK, our energy expenditure side of the equation is a little slower than normal people’s. But we still can maintain our weight losses by eating a little less or moving a little more – eating about 15 – 20% less or exercising about 15 - 20% more than normal people.
I sat there with my mouth hanging open for an hour and a half while I listened to all of this. I always suspected that it was all true, but here was the proof. On the one hand, it’s kind of depressing but on the other, I realize that nothing’s changed. Honestly, we’ve all puzzled this out for ourselves already, right?
In mulling all this information over, I’ve got several thoughts:
Maintenance IS harder than losing! Not just psychologically, but for real, measurable physical reasons. Our metabolisms are slowed down by weight loss.
This explains why so many losers regain weight. Our bodies are genetically and biologically programmed to return to our previous obese weights and will lower our metabolisms and release hormones to get us to eat more and burn fewer calories in order to regain fat. It’s a scientific fact – this is what we’re up against.
Once we reach goal weight, not only can’t we go back to our old ways of eating, we can’t even start to eat like normal (never fat) people without gaining weight. Those of us who are the reduced obese are and always will be different and we need to recognize and adapt to that fact.
Therefore, the diet’s not ever going to be over – we’re going to have to eat thoughtfully for the rest of our lives in order to defeat our bodies’ biochemical mechanisms to regain fat.
Exercise is key – in terms of the body fat equation Stored Body Fat = Food Intake – Energy Expenditure we only can safely reduce our food intake by so much (like 1200 calories/day) and then we're forced to burn off the rest through exercise, even though we aren’t going to be using as many calories as normal people do when we exercise.
The worst possible way to maintain a weight loss would be to try to eat intuitively because our bodies will be cueing us to eat more with lowered leptin levels – we need to eat non-intuitively to outwit our bodies' desire to return to obesity.
This explains why metabolic calculators don’t seem to work for many of us who are reduced obese. I always need to eat less/exercise more than any BMR calculator would indicate and now I know why – my BMR is different than that of normal and obese people. I did the BodyGem test, which measures resting EE (which you may recall is unchanged by weight loss) and extrapolates a BMR from that number. Now I know why it was so totally off-base for me – my non-resting EE (which it doesn’t measure) is 15-20% below normal. So of course all its conclusions were wrong for me.
Bottom line – track your calories and exercise and find out exactly what works for YOU to maintain your weight loss. Don’t compare yourself to what normal people eat and how they exercise – we’re not normal people. But we’re not crazy and we don’t have eating disorders – it's a FACT that we have to eat less and exercise more than normal people in order to maintain. The most important thing to take away from this is that it IS possible to maintain large weight losses with some thought and work and planning.