General Question

inunsure's avatar

What are some of the reasons why some find it easy to stay skinny and others find it hard to lose weight?

Asked by inunsure (423 points ) August 4th, 2012

Some people dont even seem to try and are naturally skinny and others go on diets try and exercise still struggle. What are some biological and nutritional reasons for this ?

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39 Answers

marinelife's avatar

Genetics, childhood eating habits.

inunsure's avatar

@marinelife
¬_¬ I was looking more for specifics, those are obvious things that could effect it.

Lightlyseared's avatar

Some people don’t notice they are eating 15,000 calories a day.

plantmoretrees's avatar

I don’t think even the, ‘experts’ know.

They say everyone can lose weight provided they exercise and diet right. I think that’s no more then 2,500 calories a day and exercise for at least 30 minutes, three time a week.

They also say cut out fatty foods, eat less ‘junk’ food etc. Because they know exactly what you eat right?

But I know fat people who eat like a bird!

The only thing they have in common is erratic to no exercise.

So make of that what you will.

DigitalBlue's avatar

@Lightlyseared jeez Louise, do people really eat that much??

Metabolism, is the simplest answer. Also, studies have shown that once fats cells are there, not only do they never really go away, they only shrink, but they also release hormones that encourage your body to eat more and to store more fat. Gaining weight is a lot easier than losing it, because our bodies are built to withstand food shortages. We’re also built to be a hell of a lot more active than we are in today’s society.

inunsure's avatar

@Lightlyseared
If some people get full at 1500 or others at 15,000 why is that?

jerv's avatar

I have a high metabolism, though not as high as it used to be when I was 15–35.

Sunny2's avatar

Some people do not ever feel full. They lack whatever it is that tells us when enough is enough. That can cause a lot of overeating just because the food tastes good. The same is true with high calorie drinks. Portion control is harder for them. If this factor is combined with lack of self control, slow metabolism, and lack of exercise, the outlook for normal weight is not good.

Adirondackwannabe's avatar

I’ve had to adjust since I was a teen. I could eat anything then. But I count calories in my head and read labels all the time. I weigh the same as I did when I got out of high school. I just have to work at it a bit more.

Mariah's avatar

Thyroid can effect both ways; hypothyroid can make it hard to lose weight and hyperthyroid can make it hard to gain weight.

BhacSsylan's avatar

*a quick note, I am a biochemist, but not a doctor or dietician, so take my words with a little salt. I’m pretty sure most of this information is correct, though.

It’s all about metabolism and the body’s particular chemistry. It’s half and half true that even the experts don’t know. We know a hell of a lot, but the problem is that our bodies are amazingly complex, so there’s still a lot that we don’t know. But we do know a very large amount about the basics.

In a general sense, the things that control your weight are mostly how much energy your body extracts from food, how much it stores and in what ways, and the ways in which it goes about burning it. All of these variables interact and can effect the end result. And while it’s true that controlling for calorie intake and use can help you lose weight, it’s really not that simple in the end (which is why something like 5% of people on diets manage to keep lost weight for longer then a year or so) because all of these can shift around.

So, to start, the energy that you extract effects it, naturally. If your body is highly efficient, you will gain more calories from food, and thus need to eat less. This is the reason fiber is so often suggested for diets, as it it very hard to break down and results in our body extracting less from your food while still making you feel full. This is also why extreme calorie-restriction diets tend to work very badly, as your body goes into ‘starvation mode’ after a little while (usually a few days) and becomes far more efficient at getting nutrients from food, counteracting the effort (and making weight gain after going off the diet very, very fast).

Now, the ways in which your body stores and uses it is also highly important, as well. While the actual forms you injest are important in terms of calories vs proteins vs fat, you body is capable of inter-converting these, to an extent. It takes more energy then just using the stuff straight, naturally, but it can do it (otherwise anyone on a strict Atkins diet would die pretty fast, or at least have some really nasty side effects, as carbohydrates are the only form of energy used by your neurons). One thing that affects this heavily is insulin levels, which inform your cells as to whether to store and use energy as carbohydrates or fats. This is why diabetics tend to gain weight, as the lack of sensitivity to/lack of insulin makes it so the body is far less able to control this, and more energy is converted to fat stores. And this is also why they can go into shock from lack of sugar, as the body can’t switch over to creating carbohydrates when the blood sugar drops too low.

And of course, how you use the energy is also affects it, and this is what is usually referred to as ‘metabolism’, which is how quickly your cells use the energy. This is regulated by a whole host of factors, one common one being thyroid hormones, produced, naturally, in the thyroid. Thus, hyper- and hypo-thyroid patients (of which the latter runs in my family, actually) tend to also have great trouble regulating their weight, because while their bodies may be able to control how the energy is packaged, it’s not as capable of determining how to use it. Your ‘basal metabolic rate’ is the main thing here, which is affected by genetics and conditions such as thyroidism, as well as how active you are. More active means a higher basal metabolic rate, and so you use up more calories on average then someone else with a lower rate. Again, though, this is also affected by what you eat, so that ‘starvation mode’ affects this as well, lowering your metabolic rate to be more efficient, and thus harder to lose weight (and do much of anything).

Now, this is also only the general body chemistry in terms of food, and neurology also affects things, as @Sunny2 and @DigitalBlue has mentioned (although, do you have a source for fat cells not dying, @DigitalBlue? Not saying you’re not correct, but I haven’t heard of that, and would be interested to read up on it). The signals in your brain that tell you whether or not to be hungry or full play a huge role, and are naturally affected by your body as well (for instance, those insulin levels again affect this). However, as I am not a neurobiologist I’m not even going to attempt to explain that, as it gets even more complicated, and can get into things like upbringing, culture, and psychology. Suffice to say it’s complicated >.<.

Uh, hope this giant block of text helps!

(also, while i also find it hard to believe that really anyone is capable of taking in 15000 calories a day, very high-end athletes tend to take in massive amounts. Michael Phelps, for instance, works on around 12000 a day)

philosopher's avatar

I was a chubby child. I exercise, I eat whole foods and little saturated fat. I fight my Genetic tendency by eating mostly fruits and vegetables.
I am married to someone who never gains weight but I can. I eat healthy and don’t eat big portions.

DigitalBlue's avatar

@BhacSsylan no, I don’t know for sure that it is true, I heard it on…. 20/20… maybe not. Some television show. This article mentions it.

BhacSsylan's avatar

Ah, okay. it doesn’t quite say that, we do turn over our fat cells. Not particularly fast, but we do (“We recycle about 10% of our fat cells each year, and every 8 years, half our adipocytes have been replaced”). That aligns more with what I thought was the case.

But that does still support the rest of what you said, it’s just that it’s more that the patterns of fat cell growth stay very constant over time, even if the cells themselves die. And it is also true that eating less won’t make them die, they die on their own over time.

DigitalBlue's avatar

@BhacSsylan right, what I heard on the show was what I said above, but no, I can’t cite it otherwise. A lot of sites are saying that it is true, but nothing that is necessarily a reputable source. Googling is bringing up conflicting information, so if you happen to find something that proves or disproves, I’d appreciate if you shared. Now I’m curious to know if it is accurate in any way.

woodcutter's avatar

I think the speed in which an individual actually eats factors in. Eating too fast because of hectic life or habit will allow us to overfill before the quit switch tells us to. There is a lag there.
Losing weight is like quitting any bad habit, so a person will need to make a lifetime commitment to keep an eye on things and never let up in order to stay successful. It’s hard.

BhacSsylan's avatar

@DigitalBlue The study cited by the article you linked (full article here, though it’s behind a paywall) makes a very compelling case by measuring carbon-14 levels, which is well understood. And a brief search finds quite a few in agreement (such as these) and nothing taking issue with the findings (with exception of some saying it’s even faster, interestingly, though those are probably different types of adipose), so I think it’s safe to say that the consensus is on the side of the slow but present turnover that they found.

jrpowell's avatar

I am 6’ and 135 pounds. My mom is 5’3” and well over 200. She totally doesn’t understand that I don’t really get hungry. I get get hungry when my body tells me it is time to eat. She gets hungry when she is bored. I’m good with a big meal and some snacks during the day.

jca's avatar

There was a recent discussion on Fluther about weight and I mentioned a NY Times article on weight issues. Someone linked it – I have to find it, or at least find the title so you all could google it.

jca's avatar

The article that discussed why some fat people just can’t lose weight, it’s called The Fat Trap by Tara Parker Pope, and it was in the NY Times, 1/1/12.

Coloma's avatar

Well menopause has caused me to plump up AND it’s like my waist has just merged into everything else. WTF! Where has my girlish figure gone this last few years. Bah humbug! lol

inunsure's avatar

@BhacSsylan
Thanks for the replies very much.

So biology plays a bit part and some people get fat not eating that much, but why are there so little fat africans and hunter gatherer tribes?
http://www.bbc.co.uk/news/science-environment-18985141

I read this article on BBC that says maybe diet has more to do with loosing weight than exercise as the hunter gather tribes only burn a small amount of calories more than us.
Are these people hungry often but cant have food as I know people who watch their calories and still struggle to loose weight. Might it be due to the types of foods they are eating not just the calories in their food?

inunsure's avatar

It would be good if they measured two societies one relatively skinny and one relatively fat, and measure calorie intake and energy used per day and see is being fat more prevalent between one and the other to see if the types of diets we eat are also a big effect just just the calories we intake.

rooeytoo's avatar

You rarely see a heavy asian person who eats a typical eastern diet. But it is a fact when these people move to a western culture, they get just as fat as everyone else. And a staple of their traditional diet is rice, lots of rice at every meal. And yet someone is always saying don’t eat rice???? I think the main culprit is sugar, it is hidden in so many things we eat without a second thought. For me personally, it is poison. If I eat sugar I want more sugar, always more. So I try to avoid it completely. And if I put on a kilo or two I immediately cut back until I lose them and get back to my optimum weight. That is a lot easier than waiting until I am 5 or 10 kilos over.

So I think the problem mostly stems from the kind of processed food modern society eats and lack of exercise compared to our grandparents who probably did manual labor 10 hours a day 6 or 7 days a week.

inunsure's avatar

@rooeytoo
I dont know how true this is. I’d like to see a lot of data on this, while in Hong kong I seen a lot of over weight asians.

The family I was staying with I think eat a mainly Chinese diet and it seemed like many were over weight, but like I said before I would like more data on this.

Also I eat a mainly rice diet and it doesnt seem to help too much but I could be a outlier

inunsure's avatar

@rooeytoo
Also I did link a study showing hunter gather societies dont burn that many more calories than us in the western world.

rooeytoo's avatar

@inunsure – I recently spent about 6 years in the bush of Australia. You could always tell at a glance which aboriginal people were from the bush because they were lean and muscular and the teeth they had did not have visible cavaties. The people who lived in towns and had access to processed foods and a grocery store were completely different body types. They were soft and often overweight with terrible teeth. So my personal experience is that those who still hunt for their food appear to be in much better physical condition than those who eat takeaway and drink so much soda and sports drink.

I have not noticed that asian people who stick with their traditional diet are getting overweight. It is been a few years since I have been in Hong Kong so things must be changing. That is a fairly westerized city also.

inunsure's avatar

@rooeytoo
The study does go on to say it might be a result of our over eating rather than exercise that is resulting in our obesity levels.

Yeah I would agree that Hong Kong itself is much more westerized, so even though I seen some people who seemed to eat a mainly Asian diet and were overweight, it was one family and I dont know how they eat all the time thats why I said it would be good to see more data from that.

What I’m trying to workout is are the types of diets we eat more important than we give credit to than mainly just watching how many calories go in and out. Maybe some diets make our bodies act differently like making us feel hungry or not allowing as much energy to be released as fast so we dont burn as much calories, etc.

jca's avatar

When you think about cave men, this is probably what we were meant to eat combined with their activity level. They probably ate some meat every day and some berries and plants, and were running and walking way more then we do. Most people in “civilized” society sit at desks and computers all day. Even those who don’t work at a desk, say, people who work in stores or factories may stand on their feet but are not walking or running much at one time (not enough to make their heart rates double, which is what I believe is necessary to be considered aerobic exercise).

inunsure's avatar

@jca
I dont want to keep reiterating the link I posted but hunter gatherers only burn a small amount of calories more than us a day.

jca's avatar

@inunsure: Yes, I understand, but hunter gatherers aren’t eating macaroni and cheese and pizza and Hostess twinkies, either. Combine that with their lack of a sedentary lifestyle and you get what we are supposed to be doing.

inunsure's avatar

@jca
The link does go on to say about that if you read it

jca's avatar

@inunsure: I didn’t read it but my statements are my amateur opinion.

mattbrowne's avatar

Because filling the stomach is all about volume and not just calories. About 700 ccm (three quarters of a quart) will do the trick.

Mariah's avatar

@mattbrowne The sensation of hunger results from a lack of calories, not an empty stomach, but it’s true that many people won’t stop eating until their stomachs feel full.

mattbrowne's avatar

@Mariah – Not true. It’s the combination of the calories actually needed and fiber to reach the 700 ccm. When people eat a big mac without large fries they don’t reach the 700 ccm, therefore they also eat large fries which extends the calories that are actually needed.

Mariah's avatar

@mattbrowne Hmm, just relaying what I’ve learned from my experiences. I was not hungry while on IV nutrition for two months, in which my stomach was completely empty but I was getting all the calories I needed. I realize this is anecdotal evidence though.

mattbrowne's avatar

Yes, it is @Mariah, and it is a special situation too. Again, just eating 700 ccm of fiber will still make you feel hungry after a short period of time. So the key is setting the right limit of calories and adding enough fibers to fill up the space that is left.

“Hunger is regulated by a complex system of chemicals that send signals between your brain and your body. When the body needs nourishment, neurotransmitters are released. One neurotransmitter called Neuropeptide Y (NPY) is important in sending messages to various parts of the brain. Scientists have recently identified two chemicals — ghrelin and leptin — circulating in the blood that communicate with NPY. After eating, leptin levels increase and inhibit the firing of NPY, so you feel full.”

http://www.dummies.com/how-to/content/how-your-brain-signals-your-bodys-need-for-food.html

Now, getting IV nutrition over a longer period of time is a completely different story. The body chemistry changes dramatically. Medical fasting can also make the feeling of hunger go away after a few days. I was talking about the normal daily life when people eat. The main problem of becoming overweight is energy density of food, i.e. too many calories in 700 ccm of solid food.

Mariah's avatar

Aha, thanks for the info.

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