Why do some people get fat while others don't?

[George Kaplin]

I have a truly abominable diet. It's pretty much 100% junk and I definitely eat more calories than I burn off. I must do. Today, for instance, I've had a box of cookies, six bags of chips, a candy bar, 2 liters of coke, a massive plate of chicken fajitas, some french fries, and, in a token concession to healthy living, one small apple. There's other stuff, too but I don't remember it. This kind of thing isn't unusual for me. However, I'm not at all fat. I mean, I don't have a six pack but, while I could stand to lose, say, five pounds, my BMR is normal. Moreover, I recently had my cholesterol tested and it was very low, as is my blood pressure. Why is it that some people can eat tons of crap and not get fat while other people have to be really careful? Moreover, what on earth is my body doing with the excess calories and stuff? Are they just evaporating? Am I expoiting some heretofore unknown loophole in the laws of thermodynamics, or what?

Thanks in advance.

P.S. I'm a 27 year old guy by the way.

[heavyarms553]

Genetic and environmental differences in diet quantity and content, nutrient absorption, basal metabolism, calorie loss from exercise, and other miscellaneous metabolic differences which are far too numerous to describe here.

Weight change = calories in - calories out. 3500 calories is approximately 1 pound of fat.

[George Kaplin]

Forgot to add that I very rarely exercise (although I do plan to change that)

[Manda JO]

Most people can eat quite a bit and not gain weight--young men in particular. The amazing thing (to me, at least) is how little extra you have to eat to gain significant weight over time. A hundred calories a day over what a person burns is ten pounds a year--which means if you take two women, both with stable weights, and one starts having a skinny latte mid-morning, at the end of a year she will be ten pounds heavier than the other woman--but anyone who was friends with the two of them would think "They eat exactly the same. I don't know why so-and-so puts on weight. Must be metabolism". So if you have friends somewhere that seem to eat the same as you but get fat, it's entirely likely that they are eating just a tad more--a tad that wouldn't even be noticeable.

TV and movies show the "fat kid" eating his head off all the time. But that isn't what does it. It's the small daily habits that add up over time--it's that skinny latte, or sour cream on your tacos, or 4 hershey kisses mid-morning. Which isn't to say a person can't eat these things--but if your habits are just a little bit in excess of your burn, it really accumulates over time.

[Cell Guy]

Have you been tested for hyperthyroidism? An overactive thyroid can speed up your metabolism which is why you can seemingly eat the world but not gain any weight. What about physical activity? You may burn more calories then you realize. Do you drive a desk everyday or does your job require some sort of physical movement? Do you drive to work or walk? Take the dog for a walk every evening? You don't need a workout a program to burn calories.

[Shmendrik]

Originally Posted by George Kaplin

I have a truly abominable diet. It's pretty much 100% junk and I definitely eat more calories than I burn off. I must do. Today, for instance, I've had a box of cookies, six bags of chips, a candy bar, 2 liters of coke, a massive plate of chicken fajitas, some french fries, and, in a token concession to healthy living, one small apple. There's other stuff, too but I don't remember it. This kind of thing isn't unusual for me. However, I'm not at all fat. I mean, I don't have a six pack but, while I could stand to lose, say, five pounds, my BMR is normal. Moreover, I recently had my cholesterol tested and it was very low, as is my blood pressure. Why is it that some people can eat tons of crap and not get fat while other people have to be really careful? Moreover, what on earth is my body doing with the excess calories and stuff? Are they just evaporating? Am I expoiting some heretofore unknown loophole in the laws of thermodynamics, or what?

Thanks in advance.

P.S. I'm a 27 year old guy by the way.

You don't eat more calories than you burn off; as you stated, that wouldn't jibe with the laws of thermodynamics.

I believe you mean your BMI is normal, not your BMR. Your BMR may be relatively high, which would explain why your BMI is not.

[Napier]

You don't have to write new laws in thermodynamics to utilize less than 100% of the fuel you take in. I don't know if you could fail to absorb some of it, or metabolize it in a less efficient chain of reactions, or run a higher skin temperature, or what, but efficiencies lower than 100% are easy to pull off. It's efficiencies above 100% that are so difficult.

[panache45]

My partner is very tall and thin; I am average height and overweight. During the first few years of our relationship, the two of us were virtually inseparable . . . we ate together, we worked out together, we both had sedentary jobs. Yet he never gained weight and I never lost weight. But we did notice one difference: He had to shit 2-3 times a day, and I did about once every 2 days. Food just seemed to go right through him, and still does.

[VernWinterbottom]

I stopped eating cookies a few months ago and, between quarterly doctor visits, lost 13 pounds.

My cholesterol was up somewhat, though. . .

[DSeid]

I certainly cannot answer for you in particular, but in general the answer is as follows:

Some variation can be as speculated above - some people absorb less nutrition. Perhaps they have subclinical and undiagnosed celiac disease or something similar ... but they don't absorb as much of what they eat as others. Be suspicious of this if you poop "floaters" in particular, or have frequent loose and especially smelly stools.

Some have high BMRs (basal metabolic rates), perhaps they are even mildly hyperthyroid, as also suggested above.

BUT the bigger group is that explained by "non-exercise thermogenesis", (NEAT).

There are three principal components of human energy expenditure (EE), basal metabolic rate (BMR), thermic effect of food (TEF) and activity thermogenesis. There are also other small components of EE that may contribute to the whole, such as the energetic costs of medications and emotion.

BMR is the energy expended when an individual is laying at complete rest, in the morning, after sleep, in the postabsorptive state. In individuals with sedentary occupations BMR accounts for approximately 60 percent of total daily EE. Three-quarter's of the variability in BMR is predicted by lean body mass within and across species. TEF is the increase in EE associated with the digestion, absorption, and storage of food and accounts for approximately 10-15 percent of total daily EE.

Activity Thermogenesis has two constituents, exercise-related activity thermogenesis and Non-exercise Activity Thermogenesis (NEAT). For the vast majority of dwellers in the U.S., exercise activity thermogenesis is negligible. NEAT, even in avid exercisers, is the predominant constituent of activity thermogenesis and is the EE associated with all the activities we undertake as vibrant, independent beings. NEAT has an enormous variety of constituents including occupation, leisure and fidgeting. ...

... NEAT is likely to contribute substantially to the inter- and intra-personal variability in EE. Argue thus; if three-quarters of the variance of BMR is accounted for by variance in lean body mass and, TEF represents 10-15 percent of total EE, then the majority of the variance in total EE that occurs independent of body weight must be accounted for by NEAT. Evidence supports this. NEAT is highly variable and ranges from ~ 15 percent of total daily EE in very sedentary individuals to >50 percent in highly active persons . Even minor changes in physical activity throughout the day can increase daily EE by 20 percent. NEAT is impacted by environment, but is also under biological control . ...

Or to put it another way:

Changes in NEAT accounted for the 10-fold differences in fat storage that occurred and directly predicted resistance to fat gain with overfeeding

In short you may just be a fidgety person, especially when you overeat, and surprisingly that's the biggest contributing factor to why some get fat and some don't when they both eat the same amount.

[komolono]

I have a friend so thin that once he was not sure whether it was his back or stomach hurting him. Now he sees his doctor monthly trying to find out if he is sick not getting fat. I remind him every now and then that if he was to find it out, I'd want it, too.
Athletes seem to gain weight after their career is over. Is it because their digestion is more efficient - I don't know. Bodybuilders use certain amino acids to build muscles - it requires some workout, too. I would be interested to know, who would survive/work longer without food - the fat or the skinny people.

[Captain Midnight]

I am overweight in the Jackie Gleason/Chris Farley mode.................

Many people who eat with me think that I will eat hordes of food at one sitting which is just not true. I tend to snack quite a lot, especially in the evenings. I do not buy things in the market that I like to eat, just because of the fact that I will eat it in one night at one sitting. Golden Grahams cereal for instance. I love that shit. Can't have it in the house though, because it will be gone in two sittings. Peanut butter is another thing. Bags of Doritoes. Forget about it, big bag, gone!

I think a lot of people in America are fat is partially because many people work in offices, at desks, in front of computer terminals. Most people eat food on the run, which is high in calories. Because of different times and schedules and what have you, it is difficult for people to cook, and people end up doing fast food or eating microwave crap.

Many poor people you see who are obese are like that because they cannot afford healthier food and instead eat fast food or what is available at the corner market which is usually garbage. One time about 10 years ago, I was very poor and went to Burger King for dinner almost everyday for two Whoppers for $2.13. Filled me up and did not cost that much. But it wasn't healthy and it did not do me any good.

Julia Child once stated is that fat gives food flavor, and this is why it is good. So to me, it is a tradeoff between eating flavorful food and eating "what is good for you". Vegetables are better for you than meat, but most of us like meat more. Boiling or baking meat is better than frying it, but most people like fried foods (admit it, if you could stay slim, you would eat fried food all the time, I sure would!). Chicken skin should be removed from the chicken (if the chicken is dead of course) but the skin is the best part of the chicken. Popcorn is actually "good for you". But who likes plain ass popcorn (I know, your crazy aunt with the limp did)? Butter, salt or sugar and caramel makes popcorn great. Mashed potatoes. Need gravy. Rice? Needs gravy or soy sauce.

It goes on and on. It's a skill and a game of moderation. However, some people (like me sometimes) treats food like a drug, something that makes me happy. You eat something like peanuts or popcorn or whatever, not because you are hungry but because it makes you feel better. It is hard to describe it unless you know it, it is akin to an addiction.

How much water do you drink? Everyone, my parents, my wife and other people have gotten on me over the years for not drinking water. Frankly, I don't like water. I don't like the taste of it, it is not satisfying to me The only time I like water is when I come in from the heat and the water is ice cold. That's glorious. I think a lot of people don't think of liquid as something that will make you gain weight. I like Gatorade. Really, I am addicted to the shit. I think of it as a happy medium between water that I hate, and sweet shit like soda which I honestly don't like. However, I found out recently that Gatorade has a lot of carbohydrates that will make you overweight, and it is only a benefit if you are someone who works out and sweats a lot (like athletes.) I'm no athlete. I sit and play computer all day.

Boozing and beer makes you fat too, which is a shame. Can't they make a diet liquor? Probably not since the alcohol is the thing with the calories. But I don't know.

I leave you with a website. Seeing this food may induce heart attacks in the skinny and the vegetarian. http://www.thisiswhyyourefat.com/

[sandra_nz]

Originally Posted by Manda JO

Most people can eat quite a bit and not gain weight--young men in particular. The amazing thing (to me, at least) is how little extra you have to eat to gain significant weight over time. A hundred calories a day over what a person burns is ten pounds a year--which means if you take two women, both with stable weights, and one starts having a skinny latte mid-morning, at the end of a year she will be ten pounds heavier than the other woman--but anyone who was friends with the two of them would think "They eat exactly the same. I don't know why so-and-so puts on weight. Must be metabolism". So if you have friends somewhere that seem to eat the same as you but get fat, it's entirely likely that they are eating just a tad more--a tad that wouldn't even be noticeable.

TV and movies show the "fat kid" eating his head off all the time. But that isn't what does it. It's the small daily habits that add up over time--it's that skinny latte, or sour cream on your tacos, or 4 hershey kisses mid-morning. Which isn't to say a person can't eat these things--but if your habits are just a little bit in excess of your burn, it really accumulates over time.

I think this is so true, and definitely my experience with my own weight and other overweight people I know.

In fact, it's quite frustrating to watch those weight-loss programmes on television where they do something like put out a table of food that the person has eaten over the course of a week, and of course it's laden with junk food, all a lovely uniform yellow colour.

That's simply not my experience. I eat a balanced diet, it's just that I eat a bit more than my peers and always have throughout my life, and that is why I'm now significantly heavier than them.

[komolono]

Originally Posted by Captain Midnight

I am overweight in the Jackie Gleason/Chris Farley mode.................
... instead eat fast food or what is available at the corner market which is usually garbage.....However, some people (like me sometimes) treats food like a drug, something that makes me happy...

I'm not suggesting anything illegal, but marijuana smokers seem to be quite fit. Google images of "pot smokers" (and of course there is a big titted girl not that slim on the first page) to get the general idea. Now, you can visit your doctor and ask if medical cannabis were an option.

[don't ask]

I know a few guys who were like the OP from high school to their late 20s. Last time I saw any of them they were all fat middle aged guys.

[Lynn Bodoni]

I recently lost a large percentage of my fat because I quit taking various medications. Some medicines apparently slow down my metabolism. Frequently, side effects of various medications include weight gain, so the doctor and patient have to balance the benefits of the medicine vs. the weight gain.

[komolono]

Originally Posted by Lynn Bodoni

Some medicines apparently slow down my metabolism.

Just came to my mind, my collegue suffered from inflammation of the pancreas and survived. He stopped eating fat and drinking alcohol (but not carbohydrates and coffee) started to look like another person - a slimmer person. I don't know about his medication, though.

[BrightNShiny]

Hey, Captain Midnight, I decided to pit you:

http://boards.straightdope.com/sdmb/...d.php?t=577228

[Dunkelheit]

Originally Posted by komolono

I'm not suggesting anything illegal, but marijuana smokers seem to be quite fit. Google images of "pot smokers" (and of course there is a big titted girl not that slim on the first page) to get the general idea. Now, you can visit your doctor and ask if medical cannabis were an option.

Unfortunately, it could also result in a bad chronic case of the munchies. ;-)

[rhubarbarin]

I used to eat a ton of crap (1 dozen Krispy Kremes at a time, etc) and weighed 95 lbs. I went through a phase where I smoked a lot of pot, ate even more crap, and weighed 100 lbs. Now I eat a only nourishing 'whole' foods (which has helped my digestion greatly) and I weigh 102 lbs on a good day. I spent a couple years counting calories - I can eat to the point that I'm physically miserable (3500 cals+ for me), and my highest ever weight was 106 lbs. I can't last long overeating, though, and once I stop I go right back down to my usual baseline of 100 lbs.

I'm 25 now and I assume someday my metabolism will slow (but then, I've been assuming that since I was 14). In my case, extra calories seem be burned off as body heat rather than building flesh. I feel very overheated and often sweat in hours following big meals. I also get extremely fidgety when I've eaten a lot which I'm sure helps burn it off. I'm already decently active (walking etc).

There's a ton of factors, we don't really know the whole story yet when it comes to individual weight.

[WhyNot]

Originally Posted by rhubarbarin

I used to eat a ton of crap (1 dozen Krispy Kremes at a time, etc) and weighed 95 lbs. I went through a phase where I smoked a lot of pot, ate even more crap, and weighed 100 lbs. Now I eat a only nourishing 'whole' foods (which has helped my digestion greatly) and I weigh 102 lbs on a good day. I spent a couple years counting calories - I can eat to the point that I'm physically miserable (3500 cals+ for me), and my highest ever weight was 106 lbs. I can't last long overeating, though, and once I stop I go right back down to my usual baseline of 100 lbs.

I'm 25 now and I assume someday my metabolism will slow (but then, I've been assuming that since I was 14). In my case, extra calories seem be burned off as body heat rather than building flesh. I feel very overheated and often sweat in hours following big meals. I also get extremely fidgety when I've eaten a lot which I'm sure helps burn it off. I'm already decently active (walking etc).

There's a ton of factors, we don't really know the whole story yet when it comes to individual weight.

Have your thyroid levels been tested? Those are some classic symptoms of hyperthyroid (inability to gain weight on massive calories, feeling hot, sweating, fidgeting). While it's "nice" in being able to eat whatever you want, it's hell on your body and can lead to ugly complications down the road if it's not treated.

[billfish678]

Originally Posted by WhyNot

[]
Have your thyroid levels been tested? Those are some classic symptoms of hyperthyroid (inability to gain weight on massive calories, feeling hot, sweating, fidgeting). While it's "nice" in being able to eat whatever you want, it's hell on your body and can lead to ugly complications down the road if it's not treated.

Like what? Just curious.

[WhyNot]

Originally Posted by billfish678

Like what? Just curious.

Heart problems, including atrial fibrillation and congestive heart failure, osteoporosis, eye problems, including bulging eyes (in a form of hyperthyroidism called Graves' Disease), dry eyes, loss of vision and most seriously, thyrotoxic crisis, also known as thyroid storm, when your everyday symptoms get turned up to 11 and your body just burns itself out very, very quickly, with fever, rapid heart rate, dehydration, vomiting, delirium and coma on the way. Thyrotoxic crisis can be deadly within hours without intensive medical intervention.

[rhubarbarin]

Originally Posted by WhyNot

Have your thyroid levels been tested? Those are some classic symptoms of hyperthyroid (inability to gain weight on massive calories, feeling hot, sweating, fidgeting). While it's "nice" in being able to eat whatever you want, it's hell on your body and can lead to ugly complications down the road if it's not treated.

I've had a full thyroid panel a few times and always tested normal. Due to poor nutrition I used to have a lot of hypo-, not hyper-, symptoms - hair loss, freezing extremities, low overall body temp (which I still have - 97 degrees), low energy, slow pulse. Thankfully I don't anymore since I've changed my diet.

[md2000]

Originally Posted by don't ask

I know a few guys who were like the OP from high school to their late 20s. Last time I saw any of them they were all fat middle aged guys.

Homer Simpson flashback to high school days...

"Gee Homer - how can you eat so much and not get fat?"

"It must be my metabolism..." [Combs his Elvis haircut and looks at a huge chunk left in the comb] "Oh well, there's lots more where that came from."

[ralph124c]

What explains morbid obesity? These people keep eating and their health goes to hell. It cannot be pleasant to weigh 500 pounds..yet their brains keep telling their bodies to keep eating-clearly some limiting mechanism is being overidden, in the metabolism of these people.Another question: people who have been starved for years (like the Nazi death camp inmates)-once they get out into normal society, do the begin eating to excess, or do the go back to their normal weights and stay that way?

[sundog66]

Originally Posted by Manda JO

The amazing thing (to me, at least) is how little extra you have to eat to gain significant weight over time. A hundred calories a day over what a person burns is ten pounds a year [...]

Although I trust that the math works out, something that strikes me as a tad facile about this view is that it would lead us to expect just as many people unknowingly *undereating* 100 calories per day and losing ten pounds a year. But in my experience of the world, the overwhelming trend is toward gaining weight rather than losing weight over time. What accounts for this asymmetry? Is it simply that eating more is more pleasurable than eating less?

Or to recast the OP's question: Why do some people (effortlessly) get fat and others (effortlessly) don't, but nobody seems to get thin without putting forth significant effort?

[Ximenean]

AIUI, it's a myth that basal metabolic rate tends to decrease with age, or at least that age in itself tends to cause it to decrease, and then you get fat. It's more like the other way round - you get fat and lose muscle due to lifestyle changes, infirmity, and very gradual weight gain in adulthood finally catching up on you. And less muscle means a lower metabolic rate, but people tend not to decrease their calorie consumption from what they're used to.

[panache45]

Originally Posted by Lynn Bodoni

I recently lost a large percentage of my fat because I quit taking various medications. Some medicines apparently slow down my metabolism. Frequently, side effects of various medications include weight gain, so the doctor and patient have to balance the benefits of the medicine vs. the weight gain.

Yes, I was able to maintain just 10-15 extra pounds until I started taking insulin. Now I've been gaining about 2 pounds/month. Many people on insulin report weight gain.

[taffygirl]

Much as we all find it easier to be simplistic and say that it's calories in minus calories expended that determines whether or not someone is fat, it just doesn't work that way. Humans are complex machines. Sure, if you fidget a lot, you may burn a total of a few hundred calories a day more than you would otherwise, and for some people, that explains why they don't gain weight. A physically demanding job may make the difference for some people. But the rate at which we burn up calories can vary a great deal from individual to individual. Period.

I am a 5'3" woman. When I was in college, I weighed 100 pounds. I ate well over 2500 calories a day. My only exercise was walking to classes--which on some days amounted to a total of perhaps 2 miles. I wanted to get up to 105 pounds so that I could donate blood. (They wouldn't let you donate unless you hit the minimum weight.) My roommate volunteered to help me gain the weight. For a week, we ate exactly the same things in the same portions--all our food was from the dining hall, and we ate all our meals together--except that she had me drinking two milkshakes a day. At the end of the week, she had gained a couple of pounds, and I weighed...100 pounds.

Now that I'm in my 50's, it no longer works that way. I engage in vigorous aerobic exercise daily: every other day, I burn off about 500 calories exercising at the gym; on alternate days, I burn off about 300 calories plus lift weights. I count calories very carefully, because if I exceed about 1700 calories per day, I gain weight. No, I don't cheat, increase portions, or overestimate the number of calories I take in. Believe me, I'd love it if that were the case. I just have to be very careful to eat less than what most people can consume to maintain their weight, or I gain. My thyroid functions normally. It's just the way my body works.

I think it's probably easiest to subscribe to the "It's just a matter of a simple equation" theory if you're naturally thin or at least have a normal metabolism. Or maybe if you're a black-and-white thinker.

Kudos to the OP for deciding to get some healthy exercise. I hope you're able to eat those vast quantities of food when you're in your fifties and sixties. I live vicariously!

[doreen]

Originally Posted by sundog66

Although I trust that the math works out, something that strikes me as a tad facile about this view is that it would lead us to expect just as many people unknowingly *undereating* 100 calories per day and losing ten pounds a year. But in my experience of the world, the overwhelming trend is toward gaining weight rather than losing weight over time. What accounts for this asymmetry? Is it simply that eating more is more pleasurable than eating less?

Or to recast the OP's question: Why do some people (effortlessly) get fat and others (effortlessly) don't, but nobody seems to get thin without putting forth significant effort?

In my experience, there are two reasons. One is that some people who would lose weight effortlessly actually put effort into not losing weight ( and I know a few) . Another is that some people do lose weight pretty effortlessly, at least sometimes. For example, when I am very busy or stressed, I tend to eat less. I' m not trying to eat less, I just don't have the time to eat and have less of an appetite. If people notice I've lost weight, I don't go into a whole story about how I didn't actually mean to lose weight, but I unknowingly started eating "x" fewer calories per day and the weight dropped off. I just say "thank you".

[Wesley Clark]

I don't know if anyone really knows for sure. The reality is if we understood the anatomy/physiology of obesity with a high degree of certainty we would probaby have effective treatments for it. As it is, the only treatments that work long term are surgery and even those can be unreliable.

So bodyweight comes down to various physiological factors, and I guess yours predispose you to being thin.

The whole 'calories in/calories out' equation is really not all that simple. There are dozens of factors that go into it outside of that. Plus a calorie of casein protein is not the same as a calorie of sugar.

[DSeid]

Originally Posted by Ximenean

AIUI, it's a myth that basal metabolic rate tends to decrease with age, or at least that age in itself tends to cause it to decrease, and then you get fat. It's more like the other way round - you get fat and lose muscle due to lifestyle changes, infirmity, and very gradual weight gain in adulthood finally catching up on you. And less muscle means a lower metabolic rate, but people tend not to decrease their calorie consumption from what they're used to.

But less muscle mass with aging is not exclusively a consequence of less exercise (albeit more resistance exercise can offset it). It is called sarcopenia.

Sarcopenia appears to begin in the fourth decade of life and accelerates after the age of approximately 75 years (Waters, Baumgartner & Garry 2000). With aging and inactivity, the most atrophy is seen in the fast twitch (FT) fibers which are recruited during high-intensity, anaerobic movements. Although sarcopenia is mostly seen in physically inactive individuals, it is also evident in individuals who remain physically active throughout their lives. This finding suggests that physical inactivity is not the only contributing factor to sarcopenia.

Muscle mass, or more accurately, fat free mass, is the prime determinate of BMR. It takes more work, more explicit resistance work, and more quality protein, to maintain or to increase muscle mass gets older.

[Lynn Bodoni]

Originally Posted by panache45

Yes, I was able to maintain just 10-15 extra pounds until I started taking insulin. Now I've been gaining about 2 pounds/month. Many people on insulin report weight gain.

In fact, some diabetics (most notably teen girls) deliberately underdose with insulin to lose weight. It's a well-known problem.

[Ximenean]

Originally Posted by DSeid

But less muscle mass with aging is not exclusively a consequence of less exercise (albeit more resistance exercise can offset it). It is called sarcopenia.

Not exclusively a consequence of less exercise, but mostly, it seems to be saying. But I take your point that your link does suggest *some* loss of muscle mass, and consequent decrease in BMR, that can be attributed fairly directly to age. How much BMR decrease is not clear.

[Gestalt]

Originally Posted by Lynn Bodoni

In fact, some diabetics (most notably teen girls) deliberately underdose with insulin to lose weight. It's a well-known problem.

That's so disturbing . . . hyperglycemia is sooo bad for your body. As a former teenage girl myself, I have to say, they are teh dubm.

[DSeid]

Originally Posted by Ximenean

Not exclusively a consequence of less exercise, but mostly, it seems to be saying. But I take your point that your link does suggest *some* loss of muscle mass, and consequent decrease in BMR, that can be attributed fairly directly to age. How much BMR decrease is not clear.

Yes, some portion, perhaps even most, of the muscle mass loss associated with aging can be the result of less resistance type activity (such as heavy physical labor). And some is the result of other changes that occur with aging, like age related death of motor neurons (which then no longer send their local growth factors into the muscles), slower protein synthesis in muscles possibly related to a decreasing population of the satellite cells that support muscle growth, and changing hormone levels (less Growth hormone, testosterone, and IGF).

BMR is, as per my cite in my first post, 3/4ths correlated with lean body mass; a loss of lean body mass (often also called "fat free mass") will certainly decrease BMR, and without a decrease in intake and/or without an increase in energy expended, cause an increase in fat mass.

That's why middle aged folk like me are really well advised to focus a bit more on resistance exercise as opposed to exclusively aerobic work-outs as we age even if we merely want to maintain our current muscle mass and fitness level. Just doing the same thing as before will not give the same results as before.

[Colophon]

Originally Posted by Gestalt

That's so disturbing . . . hyperglycemia is sooo bad for your body.

While we're talking diabetes, I have to say that, George, that diet sounds like a recipe for Type 2. Even if you're not gaining weight, it's not doing you any good.

I write this as someone who also eats loads of crap and doesn't gain weight, BTW, but do as I say not as I do....

(I do at least do quite a lot of exercise, and need about 3500 calories a day just to maintain my weight. I'm 33 and male, and no doubt I'll start to see the spread soon...)

[rhubarbarin]

Heart disease, diabetes and other chronic diseases are quite common in slender people, and IMO it's because so many of us think that as long as we aren't fat, we're 'healthy' even living vastly unhealthy lifestyles. Often someone who is congenitally thin won't get a wake-up call in the form of weight gain before they discover they have made themselves sick.

George, it's good your BP is on the low side, but low total cholesterol isn't so good if you look at the latest research. I'm trying to get mine up, as it's consistently under 160. Cancers of all kinds and depression/anxiety have been found to be much more common in people with low cholesterol. It's also important to look at your ratios, which your doctor should have on file. With your diet, I suspect you have relatively high triglycerides and low HDL. No matter the total numbers, the ratios between all these factors are much better at predicting your chances of suffering from heart disease, etc.

[Brown Eyed Girl]

Originally Posted by Gestalt

That's so disturbing . . . hyperglycemia is sooo bad for your body. As a former teenage girl myself, I have to say, they are teh dubm.

Someone one should mention to them that the average human foot weighs about 2 lbs. If you have both of them amputated you can permanently lose up to 4 lbs. What with urinary incontinence, she need never worry about excess water weight, either. Seriously, diabetic neuropathy is no joke.

Originally Posted by taffygirl

Much as we all find it easier to be simplistic and say that it's calories in minus calories expended that determines whether or not someone is fat, it just doesn't work that way. Humans are complex machines. Sure, if you fidget a lot, you may burn a total of a few hundred calories a day more than you would otherwise, and for some people, that explains why they don't gain weight. A physically demanding job may make the difference for some people. But the rate at which we burn up calories can vary a great deal from individual to individual. Period.

I am a 5'3" woman. When I was in college, I weighed 100 pounds. I ate well over 2500 calories a day. My only exercise was walking to classes--which on some days amounted to a total of perhaps 2 miles. I wanted to get up to 105 pounds so that I could donate blood. (They wouldn't let you donate unless you hit the minimum weight.) My roommate volunteered to help me gain the weight. For a week, we ate exactly the same things in the same portions--all our food was from the dining hall, and we ate all our meals together--except that she had me drinking two milkshakes a day. At the end of the week, she had gained a couple of pounds, and I weighed...100 pounds.

Now that I'm in my 50's, it no longer works that way. I engage in vigorous aerobic exercise daily: every other day, I burn off about 500 calories exercising at the gym; on alternate days, I burn off about 300 calories plus lift weights. I count calories very carefully, because if I exceed about 1700 calories per day, I gain weight. No, I don't cheat, increase portions, or overestimate the number of calories I take in. Believe me, I'd love it if that were the case. I just have to be very careful to eat less than what most people can consume to maintain their weight, or I gain. My thyroid functions normally. It's just the way my body works.

I think it's probably easiest to subscribe to the "It's just a matter of a simple equation" theory if you're naturally thin or at least have a normal metabolism. Or maybe if you're a black-and-white thinker.

Kudos to the OP for deciding to get some healthy exercise. I hope you're able to eat those vast quantities of food when you're in your fifties and sixties. I live vicariously!

I don't see how anything you wrote here contradicts the rather basic, but easily understood "calories in - calories out = weight control" model. Your body is a reactor; the calories we take in are the fuel that powers the reactor. The energy your body expends, even at rest, represents the calories out. If you take in more fuel than your body can use, you'll store it for later in the form of fat (cold storage fuel). If your reactor works efficiently and you're taking on clean fuel (normal or high metabolism with no barriers to absorption and processing), you'll expend energy more efficiently and will produce less waste and will store less fuel in the form of fat. When your reactor works less efficiently and/or takes on fuel it can't use (i.e., excessive carbohydrates, fats or proteins), those extraneous nutrients are either expelled unused or stored for later need in the form of fat.

Your 20 year old reactor is not going to be as efficient as your 57 year old reactor. The aging process is the body breaking down. Like you said, it's a machine and it's not going to last forever or even work as good as when it was newer. Ergo, it's no surprise that even with maybe 7000 more calories introduced into your diet for a week, your 20 yr old body was able to temporarily adjust metabolic rate to process those calories. Just because now 7000 more calories might net you a couple of pounds at your current level of activity and metabolic rate, doesn't mean that the formula is any more or less complicated than it was at 20. It's just your reactor is less efficient.

[Ximenean]

You can't really conclude anything from one person gaining two pounds in a week and another person not. For one thing, that's well within normal weight fluctuation. Weigh another day and the results might be very different. For another thing, it's actually pretty difficult to gain weight that fast. A 1000 calorie surplus is OK for one or two days, but try doing it for seven days in a row. You just won't feel hungry enough, unless you have some kind of eating disorder.

[Brown Eyed Girl]

Originally Posted by Ximenean

You can't really conclude anything from one person gaining two pounds in a week and another person not. For one thing, that's well within normal weight fluctuation. Weigh another day and the results might be very different. For another thing, it's actually pretty difficult to gain weight that fast. A 1000 calorie surplus is OK for one or two days, but try doing it for seven days in a row. You just won't feel hungry enough, unless you have some kind of eating disorder.

This, too.

[rhubarbarin]

Some information about the most famous overfeeding studies, most of which were unfortunately very short term with small sample sizes.

Results of the famous SIMS Vermont prison study seemed to show that some lean men can be overfed by up to 3000 calories daily over many months with minimal weight gain, need more calories daily to maintain this weight gain (BMR increase), and return quickly to their previous 'set point' once they return to a normal caloric intake.

My personal experience seems consistent with that data, but it's really the only study of its kind and probably always will be.

[DSeid]

Originally Posted by Brown Eyed Girl

I don't see how anything you wrote here contradicts the rather basic, but easily understood "calories in - calories out = weight control" model. ...

It doesn't but it seems that many forget that the basic and easily understood is actually as complex as the rest of your post makes clear. "Calories out" is a more difficult number to get ahold of, a much more dynamic entity, than many think. The concept is basic and simple, the reality is as elastic as the waistband in the pants my Mom used to buy for me back when I was a kid and shopped in the Huskies section.

I'd also like to echo the comments that being thin does not mean that you are healthy. A moderately overweight individual who eats healthy choices and exercises regularly is much more likely to have better long term health than a thin person with the habits our op described.

And about that overfeeding study referenced by rhub, my second cite in my first post in this thread was one that replicated the essence of that work in 1999 and documented that the major difference between the group that stayed thin and the group that gained weight was the tendency (or lack of a tendency) to increase NEAT in response to overfeeding.

Humans show considerable interindividual variation in susceptibility to weight gain in response to overeating. The physiological basis of this variation was investigated by measuring changes in energy storage and expenditure in 16 nonobese volunteers who were fed 1000 kilocalories per day in excess of weight-maintenance requirements for 8 weeks. Two-thirds of the increases in total daily energy expenditure was due to increased nonexercise activity thermogenesis (NEAT), which is associated with fidgeting, maintenance of posture, and other physical activities of daily life. Changes in NEAT accounted for the 10-fold differences in fat storage that occurred and directly predicted resistance to fat gain with overfeeding (correlation coefficient = 0.77, probability < 0.001). These results suggest that as humans overeat, activation of NEAT dissipates excess energy to preserve leanness and that failure to activate NEAT may result in ready fat gain.

[Wesley Clark]

Originally Posted by rhubarbarin

Some information about the most famous overfeeding studies, most of which were unfortunately very short term with small sample sizes.

Results of the famous SIMS Vermont prison study seemed to show that some lean men can be overfed by up to 3000 calories daily over many months with minimal weight gain, need more calories daily to maintain this weight gain (BMR increase), and return quickly to their previous 'set point' once they return to a normal caloric intake.

My personal experience seems consistent with that data, but it's really the only study of its kind and probably always will be.

I have read other studies, but probably couldn't find them online. However the jists of some are on overfeeding studies: Everyone is given X extra calories a day over their maintenance calories (sometimes 1000 a day for 90 days or something). Weight gain varies from 2-30 pounds, and the % of fat vs. LBM also varies wildly.

On underfeeding studies: Same thing, X fewer calories than maintenance and the results are weight loss varies wildly, and the % lost via LBM vs fat varies wildly

Basically, people are really different and even in small studies of a few dozen people you see rates of weight gain and loss that are polar opposites (one person may gain 30 pounds and have all of it be fat if they are force fed 100k extra calories over 100 days, another may gain 5 pounds and have 3 pounds be muscle). The 'calories in/calories out' equation really doesn't take into account the dozens of minor and major biological changes between individuals that can drastically affect how many calories end up going in and how many go out.

I am fat, but I'll never be 500 pounds. Even if I wanted to be, I dont' think I could do it. I'll never be 120 pounds either. But some people naturally stabalize at those weights.

[RaftPeople]

Here's a relevant article about high fat diets altering brain cell insulation and thus altering feedback signaling:

http://machineslikeus.com/news/brain...lack-willpower

[Beware of Doug]

People get fat because of God. It's His punishment for their lack of moral discipline, obedience to authority, and industrial work ethic.

[panache45]

Originally Posted by Beware of Doug

People get fat because of God. It's His punishment for their lack of moral discipline, obedience to authority, and industrial work ethic.

This explains why Jesus always looks anorexic.

[Voyager]

A few years ago there were news reports about a study that showed that people had very different activity profiles, even at desks. Some people tended to stay in one place all the time, others moved around all the time. I'm of the latter, inefficient, variety, and I suspect this is one reason I'm quite think even at almost 60, and even eating lots of stuff - not junk, but lots. I also fidget a lot, and when I walk, I walk a lot faster than most normal people.