Fat and Thin: What Do We Know?

[RTFirefly]

Over in GD, there's a thread (http://boards.straightdope.com/sdmb/showthread.php?threadid=23088&pagenumber=1) that started off asking whether Calista Flockhart and the other ultra-thin women populating TV and movie screens these days were helpful role models for people struggling with being overweight. Part of the discussion has turned into a debate of sorts about whether it's easier for some people than others to gain/lose/maintain weight.

Some of this is in the realm of science, although whether the science has been done yet may be another matter.

So that's what this thread is asking. What do we know about the following?

1) Do all people metabolize food at pretty much the same level of efficiency, or are some people more efficient than others at turning the same meal into protein, carbohydrates, and fat that the body can use? And if the latter, what sort of variance in efficiency is there?

2) Do all people burn pretty much the same number of calories when they do identical physical tasks (e.g. walk 1/4 mile at a prescribed pace) or do some people burn more calories than others to get the same work done? And if the latter, how much variance is there?

3) A great deal of anecdotal evidence suggests that when overweight people lose substantial amounts of weight, they tend to gain most of it back within a few years. Have any scientific studies been done of this phenomenon, and what have they shown?

4) In particular, have any studies been done comparing the weight gain of people who've recently lost substantial amounts of weight with that of people who haven't recently done so?

If anyone else can think of some relevant, well-focused questions, feel free to add them to the discussion. And if you know of a study that's been done that doesn't directly answer one of these questions, but seems to have relevance to the broader question of to what extent we differ in the ease with which we gain or lose weight, or maintain a healthy weight, please bring it up. We're arguing on the basis of anecdotal evidence over there, which tends to generate more heat than light.

[Earl Snake-Hips Tucker]

Well, Rufus, you have asked some good questions, and I hope someone finds some real answers, because I've wondered that myself.

I do have an "opinion" on #3. It's not scientific. I haven't done any studies, but it is plausible.

IMO, "dieting" is the reason that most people gain weight back.

A "diet" implies that it is something temporary to achieve a goal. For example, a person wants to lose "X" number of pounds.

So the person goes on a diet and loses "X" number of pounds, typically by using whatever diet-du-jour (which probably entails some kind of artificially low caloric intake).

OK, what then? The diet is over.

Typically, then, people go back to doing the same things that got them there to begin with.

An artificially low caloric intake is guaranteed to lose weight, but once you've accomplished that "goal," it's not something sustainable.

As someone who has been there, I know that "diets" will cause you to lose weight, but they won't *keep* it off.

That is accomplished only by permanent lifestyle changes.

People are quick to talk about "slow metabolism," and no doubt that's true for some folks.

But not the majority--not by a long shot. Weight is for most caused by what's at the end of your fork, not what's in your genes.

[Squee]

3) A great deal of anecdotal evidence suggests that when overweight people lose substantial amounts of weight, they tend to gain most of it back within a few years. Have any scientific studies been done of this phenomenon, and what have they shown?

The problem lies with fat cells. Once they are created, they are with you for life. What dieting does is reduce the size of these cells, but the number remains the same.

Lemme dig around for a link.

[Athena]

Here's what I believe is true on these topics:

#1) No idea. Good question, though.

#2) I believe that # of calories burned is based on weight. If a 150 pound person walks a mile in 20 minutes, he or she burns the same # of calories regardless of height and physical fitness. Meaning: a 5' person who is sedentary and weighs 150 pounds will burn the same # of calories on the 20 minute walk as the 5'8" athlete who weighs 150 pounds.

#3) Most of the studies I read agree with Mjollnir. If you go back to your old eating habits after you lost the weight, you're going to gain it back.

#4) The book "Thin for Life" details the habits of people who have lost more than 20 pounds and kept it off for more than 3 years. I believe there's another, larger study going on, but I can't recall the name right now. I'll see if I can find it.

[Squee]

The link I promised:

The Truth About Fat Cells (http://www.allhealth.com/healthexperts/fitness/qa/0,4801,6351_380-2,00.html)

[Athena]

Here's the "other, larger" study that I mentioned in my first post:

http://www.uchsc.edu/nutrition/nwcr.htm

[handy]

How it all works, howthingswork.com search for 'fat'

[VarlosZ]

Yes, I'm sure that there is some genetic variance in general metabolism rates. However, I doubt that it is a large one. Likewise, I'm sure there is a small genetic variance is caloric burn.

Does this make it tougher for some people to lose weight? Sure. Is this why some people are dangerously obese and others are skin and bones? No. You have to eat -- a lot -- in order to be really fat. It helps if you avoid all excersize as well. My weight is exactly what one would expect given my diet and excersise (5' 11", 198 lb. I eat plenty, but I don't REALLY overdo it). In general, this is true of everybody.

[phouka]

Please don't forget that aside from just metabolism, there are valid medical reasons that some people gain weight in spite of good eating habits and exercise.

The chief of these are hyperinsulemia and insuline resistance. Insulin is the hormone which governs blood sugar absorption into muscles and organs. When a person become insulin resistant, glucose remains in the bloodstream because the muscle and organ cells aren't responding to the insulin present. Eventually, the pancreas produces more insulin (hyperinsulemia) to force the absorption of glucose. The more resistant a person becomes, the more insulin they manufacture, and the more resistent they become. Eventually, the body begins to store glucose as fat because muscle and organs don't respond. At the same time, muscle and organs are starved for glucose. When fat cells become insulin resistant, there's no place left for the glucose to go, and the person becomes a Type II diabetic.

It's a chicken/egg problem. Being overweight predisposes a person to insulin resistance and hyperinsulemia. Having insulin resistance and hyperinsulemia tends to cause a person to become overweight or more overweight. Exercise helps - dramatically in some instances. Changing eating habits helps - again, dramatically in some instances. However, neither are 100% sure to cure insulin resistance and hyperinsulemia. What's worse is that someone with hyperinsulemia and insulin resistance tends to crave the very foods that make their condition worse.

There's no doubt that the average American diet is unhealthy. Too much fat, too many simple carbs, not enough lean protein and green vegetables. I think what we're seeing now is the consequence of this diet 20 and 30 years down the line - after a huge amount of damage has already been done and when eating and exercise habits are extremely difficult to change. More and more children are obese. More and more cases of adult onset diabetes are occurring at earlier ages. It used to be that adult onset diabetes didn't occur until the mid to late 50s. Now they're seeing people being diagnosed in their late 20s and early 30s.

People who eat healthy from the beginning are much more likely to remain at a healthy weight. People who don't eat healthy from the start are more likely to become obese. People who don't eat healthy and have a genetic predisposition to conditions like hyperinsulemia, insulin resistance, PCOS, Syndrome X, high cholesterol, and others, are in serious danger.

[labdude]

1) Do all people metabolize food at pretty much the same level of efficiency, or are some people more efficient than others at turning the same meal into protein, carbohydrates, and fat that the body can use? And if the latter, what sort of variance in efficiency is there?



I really don't intend the following to be an insult to anyone.


Applying my knowledge of hog farming to humans would lead me to believe that people have very different rates of metabolism. There are some hog types (both breeds and individuals) who won't gain weight no matter how much you feed them. You can feed them corn all day and get almost no weight gain. This is the basic principal behind stock improvment methods. You kill the animals that dont have an efficient food in vs weight gain ratio, and don't let them have babies.


michael

[astro]

Have gained and lost for years and years the answers below are based on empirical observations I have made regarding calorie counting / charting and weight loss for myself. If someone knows better I would be glad to stand corrected.

The bottom line for the vast majority of overweight people is simply that we eat too much and don't get enough exercise (no foolin'). Re "eating too much" I'm not talking Mr. Creosote type gluttonly here but the cumulative effect of lots of a "little bit too much" over time. Everyone has tales of the thin person that eats likes a horse but truth be told overweight people are overweight mainly because they eat more calories than they can burn, are more sedentary and don't burn the calories (a vicious cycle).

"Why?" askes the non-fat person. Well the real answer is simply that eating is pleasurable and more is (at the time you are eating) better than less. I really think I "enjoy" food more than my thin friends overall.

I also think overweight tending people's internal "satiation" gauges operate less efficiently and less quickly than those of less overweight tending people. Overweight people tend to eat slightly more quickly and by the time our brain chemicals say "Whoa big fella (or gal)!" we've already eaten too much relative to our body needs.
It always impresses me how a thin friend can push the plate away with half the entree uneaten and no sign of internal struggle. Their brain has simply said "You're done - the tank is full... Stop eating - you no longer DESIRE that prime rib."


People have large variations in metabolic efficiency re *speed* of absorption and how blood sugars react but I would suspect overall differences (given sufficient time for processing)over time are relatively small even between fat-thin as to how body ultimately processes food.
I believe overweight people also tend to store excess calories as fat *slightly* more efficiently than thinner people. Not a huge difference for each meal but cumulatively it adds up to a large weight gain over time.

Regarding relative energy / calorie expenditures there might be some some variance depending on body type but calories consumed over time for given activity are generally pretty constant across humans and are primarly related to how much energy it takes to move/carry blood/heat up etc. re the body mass of the specific individual depending on activity being performed. This is primarily a heat/fuel equation.

Re keeping weight off,most weight is ultimately gained back. Some individuals can keep it off but these are in a relatively small minority and these folks need to faithfully follow fairly regimented programs to keep it off. It almost never never "stays off" naturally... sigh.



QUOTE]
Over in GD, there's a thread (http://boards.straightdope.com/sdmb/showthread.php?threadid=23088&pagenumber=1) that started off asking whether Calista Flockhart and the other ultra-thin women populating TV and movie screens these days were helpful role models for people struggling with being overweight. Part of the discussion has turned into a debate of sorts about whether it's easier for some people than others to gain/lose/maintain weight.

Some of this is in the realm of science, although whether the science has been done yet may be another matter.

So that's what this thread is asking. What do we know about the following?

1) Do all people metabolize food at pretty much the same level of efficiency, or are some people more efficient than others at turning the same meal into protein, carbohydrates, and fat that the body can use? And if the latter, what sort of variance in efficiency is there?




2) Do all people burn pretty much the same number of calories when they do identical physical tasks (e.g. walk 1/4 mile at a prescribed pace) or do some people burn more calories than others to get the same work done? And if the latter, how much variance is there?




3) A great deal of anecdotal evidence suggests that when overweight people lose substantial amounts of weight, they tend to gain most of it back within a few years. Have any scientific studies been done of this phenomenon, and what have they shown?





4) In particular, have any studies been done comparing the weight gain of people who've recently lost substantial amounts of weight with that of people who haven't recently done so?



If anyone else can think of some relevant, well-focused questions, feel free to add them to the discussion. And if you know of a study that's been done that doesn't directly answer one of these questions, but seems to have relevance to the broader question of to what extent we differ in the ease with which we gain or lose weight, or maintain a healthy weight, please bring it up. We're arguing on the basis of anecdotal evidence over there, which tends to generate more heat than light.
[/QUOTE]

[Needs2know]

#1...No all people do not metabolize or burn calories the same. It is a proven scientific fact that muscle burns more calories than fat. Hence if you are trying to burn more calories the popular idea these days is to build more muscle mass. When you drastically cut back on caloric intake the body will naturally slow down to accomodate. Also many people when they diet will reach a plateau, the common cure for this is to boost their metabolism to burn more calories. This is usually done by increasing their exercise level. There is also some type of connection between eating habits and metabolism. People who eat several small meals a day, seem to burn calories more efficently than those who eat 3 large meals. And just the other day I read that it is a fact that their stomachs are smaller. This article said that you can decrease the size of your stomach by 36% if you begin eating 5 to 7 small meals a day and maintain the practice. There have also been some theroies as to body type...endomorphs, ectomorphs, whatever. If you are long and lean with a straight up and down type of body you tend to stay that way, etc.

#2...Every chart I have seen showing calorie burn during exercise does not take height, weight or body structure into account. I have always taken this to mean that a calorie burned is a calorie burned. After all a calorie is only really a measure of heat. Although I am not sure about this I don't think you can compare calories burned during say a round of kickboxing to calories burned while you are sleeping. This is an interesting question.

#3...What I have read and found very interesting about people who remain overweight for long periods of time is that they increase bone mass. The body must somehow compensate for having to carry the extra weight. Yes, many people are what they call "yo-yo" dieters. (I fall into this category.) They will lose a substantial amount of weight but within 2 to 3 years slide back into poor life habits and gain most of it back. (I have been pretty successful this time. The trick is when you find yourself slipping back into old habits to get right back on track again.)

#4...I'm not really sure what this question is about.

Needs2know...why I can't just grub and lay around and still look good in my bathing suit! Life would be wonderful then.

[dasmoocher]

Didn't read everything, but has anybody mentioned leptin?
This hormone might be the most important with regard to maintenance of body fat.

Unfortunately, obesity is almost certainly genetic in the terms of leptin levels produced or the amount of leptin receptors produced. Caloric intake and expenditure certainly have a role. (Within in a year I lost 15 lbs by riding my bike to work every day instead of driving). But levels of leptin control the amount of fat deposited and maintained by your body and they can't be changed by diet or exercise. This is why most people on diets gain back lost weight after going off the diet.

This is a simplistic answer, but I could provide a journal article or two if anyone is interested. I had the chance to talk to and hear a talk by the guy who discovered the hormone just recently.

[dasmoocher]

Sorry, but my previous post was off the top of my head after happy hour. Leptin levels can be manipulated, but this isn't with regard to 'natural genetic' levels produced but because of feedback mechanisms, which regulate all hormones. But there is a 'natural setpoint' for leptin--so to speak, and therefore a bodyfat setpoint.

Now I'm going to have to dig up those articles and re-read them-ugh.

[meara]

I believe the phenomenon of weight gain after dieting is not just bouncing back to the original weight (which is perfectly reasonable if you're no longer on the diet) but rather gaining another 10-30 pounds on top of that. A lot of obese people will tell you that they've dieted their way to the top. They starve themselves to go from 160 to 130 and then bounce back to 190. Then they starve back down to 140 and bounce up to 220. So on and so forth.

I'm not sure why this happens, but I would guess it is because you tend to lose muscle when you lose weight unless you make a conscious effort to avoid it (by lifting weights, swimming, etc.). On the way back up, you are not likely to regain that muscle right away, so when you reach your old weight and are eating as much as you used to, you won't have as much muscle to burn those calories and will gain even more.

Months down the road, your body should have regained muscle to carry around the weight, but meanwhile you've gained a bunch of fat cells that will never go away -- soo.... you don't go down again and perhaps even start eating more to feed those muscles.

[meara]

Oops! It looks like I was wrong about the "more fat cells" part. Apparently (according to allhealth.com) you never get more cells, you just majorly expand the ones you have.

The result is the same, though. Once expanded a certain amount, the cells tend to stay that way and it's harder to lose weight or keep it off without exercise.

[Margarita]

There are obvious variances in one's weight gain/loss/maintenance depending on developmental stages (i.e., puberty, menopause, aging, etc.) I personally was a very thin child until about age 9, during which I ate whatever my mom said to. From 9-14, I was hideously obese, and ate mostly raw vegetables and lean protein. When puberty hit, I lost 120 lbs. (through no effort of mine) and until 25, consumed a steady diet of high-fat, high-carb, high-protein, very high-calorie foods with no weight gain. I'm talking four Big Macs at a time, plus fries and a shake! I am and always have been completely sedentary, and to this day, I can scarf two pizzas a night and my weight stays within a five-pound range. The only oddities in my diet are that I don't consume a lot of refined sugars, and I do consume a fair quantity of caffeine. I suspect my metabolism, or my processing of all the junk I put into my body, will change again whenever I enter menopause (or maybe pregnancy could do it, too.)

Just a thought...

[egkelly]

A question for those contemplating LIPOSUCTION: once they suck those nasty fat cells out of your body, can you still gain weight? If not, I'm getting my pennies saved to have an appointment with the vaccuum cleaner!

[Earl Snake-Hips Tucker]

Sure you can gain weight. You just gain it somewhere else.

[RoboDude]

I think the "yo-yo" phrnomenon can be partly explained by the fact that the human body is designed to cope with food shortage much better than with surplus. When people starve themselves in order to lose weight, their metabolism decreases to compensate. When they stop dieting and gain more weight than they lost, their bodies are essentially trying to store energy in case of future shortage, and os the cycle continues.

[HorseloverFat]

Now thats something I never understood. Why would you pick a complete stranger and make them a role-model, why even have a role-model? Are we completely unable to think for ourselves?

Exactly how does one's natural weight even come into consideration for a 'role.' She's thin, her genetics make it so. She is an actress, by defination she isn't being herself but a character someone dreamt up.


Everytime I hear 'role-model' I get reay for some holier than thou right-winger pointing out normal flaws in normal people or some unbelievably overblown media-created issue about celebriities.

[rackensack]

When this topic started, I wanted to be able to refer to an article I'd read some time ago. Problem was, I couldn't remember whether it was in Harper's, The Atlantic Monthly, or The New Yorker, or who the author was.

This weekend, I happened across the new book by New Yorker staff writer Malcolm Gladwell, [i]The Tipping Point[i]. I finished it before going to bed last night, and noticed that there was a reference to Gladwell's web site, http://www.gladwell.com. Today, I checked it out, and lo and behold, there was the article (http://www.gladwell.com/1998_02_02_a_pima.htm) listed among his New Yorker pieces.

The article discusses what science has learned about obesity and weight gain and loss from a fairly comprehensive study over the last thirty-some years of the Pima tribe in New Mexico and from various other experiments regarding the effects of genetics and other physical factors on metabolic rates, etc. The upshot is that there's a lot more at work than lack of willpower in many cases of obesity, and that once the body stabilizes at a "setpoint" (a body weight that's been maintained for some time), the metabolic system will go to great lengths to maintain that weight, even in the face of dramatically reduced caloric intake and increased exercise, even for years at a time, until a new setpoint is established. Not the most encouraging news in some ways, but it at least holds out the hope that we may soon understand the physical processes involved sufficiently to make the hard work of dieting and exercise much more likely to have the desired result, instead of boomeranging catastrophically.

[gigi]

{QUOTE}
Why would you pick a complete stranger and make them a role-model, why even have a role-model?
{/QUOTE}

It's not so much that individual people are role-models in terms of ideal weight, but that everyone shown in the media is below-average weight. Watch it long enough and you get the sense you are unattractive and a freak in comparison to this societal standard, and you take potentially drastic and life-threatening measures to conform and be lovable. (Like that song by The Story, "everyone will love me when my ribs show clearly and my thighs are thin even when I sit down.")

{QUOTE}
Exactly how does one's natural weight even come into consideration for a 'role.' She's thin, her genetics make it so. She is an actress, by defination she isn't being herself but a character someone dreamt up.
{/QUOTE}

Unfortunately, when the character is defined as a young "successful" woman (e.g., Ally McBeal), this is synonymous with thinner-than-average. How does blonde hair or beauty come into consideration? An actress who interests the viewer by being this image of "perfection" is considered optimal. This leads to the idea as above that this should be attainable for the rest of us who clearly aren't trying hard enough. (no I'm not bitter...:-)


Also, it seems to me intuitively that the same activity level for the same period of time would require more work for a heavier person (more energy to carry more weight), and that the charts reporting calories burned must be an average...?

[Jois]

Nature just started an Insight Section and its introductory feature was "Obesity in the new millennium" starts on page 631-677 and on page 538 even discusses leptin - 6 April 2000 / volume 404 / go to http://www.nature.com and see how much of it has been put on the web for freeeeeee. Too close to supper or I'd go look myself.

[dasmoocher]

You need to subscribe to one of the Nature journals to be able to get the full text of the articles.

The article 'Whatever happened to leptin?' by Marina Chicurel was mentioned during the discussion with the guy who discovered the hormone. She's a free-lance writer and I got the impression that she might not have the strongest science background. It seems her grasp of the research was flawed, but then again, the guy might have just been defending his turf. I'll have to read it the old fashion way-in the library.