With an increase in the level of obesity in the developed world, do people think obesity is in our genes or does our more fast food, convenient lifestyle have a lot to do with it?

I honestly don't think that obesity is in our genes. Genetically, there are people who are larger than others but not obese. Obesity has more to do with out lifestyle choices than anything else. However I do believe genetically, it is easier for some to lose weight more than others.

Hey, I'm relevant!

Weight - or rather, tendency to a certain weight - is at least partly genetic. My mother is skinny as a rake, and my father is quite big - and I've always had a tendency to be pudgy ever since I was a kid. So for some people, becoming obese happens a lot more easily and a lot faster.

Having said that, I'm not obese, and I never will be. Genetic predisposition is never an excuse for anything; if I chose to eat only fruit, vegetables, and protein pills I could be skinny as any almost-animate catwalk corpse. As it is, I choose to eat reasonably healthily and walk everywhere (alright, so that is partly because I don't have a car :P), and a moderate lifestyle has left me at a moderate weight, of which I'm really rather fond.

It also very telling that you cite an increase in the developed world - it's becoming harder and harder to point at developing countries and say "They're not starving, but they don't have a single McDonald's and they're mostly pretty slender", simply because almost every country in the world has been infested by McDonald's and the like. But if you think back - that statement used to be entirely valid, and shows rather a link between fast food and lazy lifestyles, and obesity.

As with almost everything, nature and nurture are both big factors. But there is (almost) no good reason why anyone, even someone with "fat genes", should be obese.

There is some genetic link, certainly... your natural metabolism will regulate how you handle food energy, and whether you store it or get rid of it... If you have a high metabolism, it can be easier to stay slim (and in some cases, make it difficult to not get dangerously skinny unless you make an effort to eat a lot). If you have a low metabolism, it can be difficult to stay slim (and in some cases, very difficult unless you're very careful of what and how much you eat).

But at the same time, there's a basic equation involved. Food goes in and gives you energy, nutrients, and fat. Your body needs a certain amount of it to survive day to day, and depending on your metabolism, may choose to store a certain amount of it in reserve. If the amount you eat exceeds the amount your body needs, it may end up storing more of it, depending on your metabolism. If the amount you eat is not as much as your body needs, it may use up some of your reserves to make up the difference. For everyone, there is a healthy amount to eat to maintain a normal weight - that amount may vary from person to person, but if you don't exceed it, you're not going to get obese. Eat less, exercise more. If you have a low metabolism, you need to work harder at it, but it still works.

I know there are some individuals with extremely low metabolisms, and for those it's quite difficult to lose weight and keep it off. There's also individuals with actual medical problems which may contribute to weight gain. However, there's also a heck of a lot of people who eat a whole lot of fatty, unhealthy foods, don't exercise, and then wonder why they're packing on the pounds - and choose to blame genetics when it's really just a matter of needing to get mobile more often and eat more carrots than cake.

I agree, its a genetic issue with heavy environmental influence. There are so many genes controlling rate of metabolism, therefore there has to be a genetic link to it, but notice that better developed countries (USA, for examply) have the highest % of obsese citizens. That's not to say they're all carrying the same genes because even other gene populations that migrate into such countries experience similar effects upon transition of diet.
There is genetic predisposition, but environmental effect on it is at least half as much.

It's mostly in the lifestyle. There are genes that make us predisposed for obesity, but they've been found more in Europeans than Americans.

I live in two places: A small house in the suburbs where I live/go to school during the week, and a condo in the heart of a small town where I go on weekends/during vacations.

In the suburban house, I can't walk ANYWHERE. It's houses, houses, houses, more houses, school, and houses. The closest thing to my house is a small gas station/corner store, but I never go there because the crappy cliques hang out there. So, 90% of the time, I have to drive somewhere.

In the condo, I walk almost everywhere. It's very hilly, but I don't care because I like walking. Everyone in town is friendly, so I stroll through main street every day. It hasn't been taken over by big-chain stores, so I get to grab a REAL fruit smoothie for lunch at eclectic shops. Most importantly, the town is SAFE, so I can actually convince my parents that I won't get raped if I walk alone.

See the difference? I'm average in terms of weight, and excellent in terms of health.

I think, combined with lifestyle choices, expansion of suburban areas and convenient chain stores have driven obesity rates up. People have become too lazy to cook, which is ludicrous. I cook most of my meals; if I don't, I try to make the best choice. It's not hard, but convenience of fast food might make people think it is.

I think it's largely based on your lifestyle and your own habits and choices, but... well, I really think there is some sort of genetic factor involved with this. As HP pointed out, some people are genetically more prone to gaining or losing weight, and I think some variation of that rule applies to most people. But with a very few certain people, I really do think that they can't maintain a healthy weight without getting outside (and possibly even medical) help. Now I don't know how much of that is actually something genetic--I suppose it really could just be an incredibly slow metabolism--but I really do think there is something more involved with those people than just eating right and getting enough exercise.

For the majority of the people in the world however, it's definitely lifestyle. The people I was talking about before were the exceptions... for the most part, it's their own fault when people end up overweight. If they would just make the right eating choices, cut back on the things they don't really need and maybe up the amount of exercise they're getting, then I think they'd be fine. It's difficult in today's society, especially with all of the convenient fast foods and non-exercise related means of transportation available, but it really can be done with just a little bit of effort.

That's my two cents. I don't know how much it's worth, though... I was eating a bag of potato chips as I wrote this.

If it were in our genes I would be seeing obese people in starving countries/communities, but I don't.

The genetic part just affects how well/fast you digest the food you eat but it really is the quantity and quality of food you eat combined with your lifestyle that will have 99% of the effect.

I believe some of it is genetic and some of it can be caused by bad eating habits that are learned in a household or developed on their own. I am obese. My mother is obese, my father was always healthy and slim. My sister is also obese. Now that I'm older, I do beleive that it was both genetics and bad eating habits that took part in my large body that I now sport around. I have the exact same body shape as my mother. When we both gain weight, is goes to the same spots on our bodies. I know that I was taught how to cook food a certain way(a lot of oil and a lot of frying). So both played a part in my life.

No offence to anyone here, but I think it's ridiculous that it's in our genes. Weight is an environmental factor; how do you account for the countless slim people out there who have obese children yet have no history of obesity in either parent's family tree? The answer is their lifestyle. Read any Science GCSE textbook and it'll tell you so
However, in some cases, such as Prada-Willy syndrome, I will concede that it is genetic...

I don't know if it's genetic or not, but it definitely is linked to some aspects of our body. Especially metabolism, like some people have said, not to mention thyroid problems and other such issues. As, of course, it depends on lifestyles.

I am one of those people with an insanely slow metabolism. I exercise daily, half an hour of uninterrupted, fast paced exercise (which I plan to increase, but I do it gradually) and I still have to be very careful what I eat. My diet is balanced. Sweets and junkfood are a very occasional treat for me or else they pile up. In fact only last week I've helped out with a friend's gardening (aka hard labour in the hot sun for hours) but his wife kept serving snacks and unhealthy stuff and despite everthing I gained like half a kilo. Am I bitter? Definitely I wish I had the kind of metabolism that allowed me to indulge in food that I unfortunately love.

But what I mean to say is, for some it's far more difficult to maintain a healthy or even desireable weight. I know the ideal should be "healthy" but some of us want to also fit in that nice tight top and low waist pants, so we need to work harder. Interestingly enough, I do have my mother's body shape and she also has a tendency to gain weight easily, she has been obese for most of her life.

It's a little of both. Your genetics kind of determine how you store weight (and where). For some people, it really is harder because of genetics. My family, for instance, is really goofy. My sister has always been very active (she had been on the varsity swim team and had swam for all her life) but the genetics she got were more of my moms where she just gained weight more and more as she got older. I work out just as much (I was a dancer my whole life), but I'm about 150 lbs or more lighter than my mom and sister. I have more a the body from my dad's side of the family where obesity doesn't run. The majority of the people on my mom's side of the family are over 250 lbs. Everyone single person on my Dad's side of the family are considered a healthy weight if not sometimes too skinny. But, I think you can also beat genetics if you work hard enough. Look at "The Biggest Loser."

flashbangg - Of course part of it is environmental, but the way our bodies handle food varies from person to person, and that part can be genetic. Some people have a harder time than others keeping their weight at a normal level. I personally have a very high metabolism, so it takes very little effort for me to stay at a normal weight... in fact, there's been times where I have to make an effort to not get too skinny, as if I'm active a lot and not eating a ton, the weight just drops right off me. Other people might be able to have the exact same activity level and intake and not lose weight because of their bodies doing things a bit differently. So there definitely is -some- genetic influence... but it's not everything, and except in the case of actual physical abnormalities and disorders, it's something that anyone can overcome if they eat less, eat healthier and exercise more.

flashbangg- No offense, but have you actually taken a genetics class. Of course the obesity dilema is getting worse because serving portions are way off...which is where that is coming from. But I have studied genetics in Uni and it part of it IS genetics. It is genetic on how you hold on to your weight. I bet you gain weight in the same places as the rest of your family. Some people are born with a slower metabolism which causes obesity. Of course if you eat like a bunny and exercise, it's not impossible to overcome, but it mostly has to do with the metabolism. Check those textbooks again.

I'd say underlying genetic influence, but predominantly lifestyle. Not only do we have variation in metabolism and tendancy to lose/gain weight, but we also have huge variation in body size and shape. I'm not talking about the amount of excess fat being carried, but about frame & stature, muscling, etc.

All of this is obviously strongly influenced by lifestyle. Were it not, I seriously doubt that we'd be seeing the increasing obesity 'epidemic' that is occuring at present. However, I don't think that the 'lifestyle' component is restricted solely to eating and exercise habits, but other changes in our society as well. I think it also shows that for most people, weight can be controlled with a healthy lifestyle.

I have noticed in particular the number of overweight and obese children around, and I think this is the most serious part of the increasing obesity problem. It actually reminds me a bit of those nostalgic "child of the X0's" emails that go round every so often. 'In my day' (I am 23), we were turfed outside on weekends and school holidays to play - we'd play cricket, footy or whatever in somebody's back paddock...basically, we'd be out mucking about all day. All the sugary drinks, crisps and fast food were a rare treat, and whatever junk food we did eat was well and truly utilised. When our parents let us out like this, it was considered safe - mine was a small town in semi-rural area, we knew almost everyone, there was very little traffic apart from on the main road. You get the picture. Now though, whether the risk is real or inflated by media hype, I think there would be very few parents who would let their kids play like ours did. So rather than going out, they sit and watch television or play computer games instead.

I think that that other lifestyle changes form part of the underlying problem. Many people seem to be working longer and longer hours in sedentary jobs. They have less time for formal exercise, and junk food becomes a thing of convenience because they don't want to go home and cook after working a 12 hour day. you then have the added problem of these eating and exercise habits being passed on to their kids. Consider income and food prices too. I don't know about the price of meat (I'm vegetarian), but the price of vegetables, rice, etc. has gone through the roof. My grocery shopping costs me almost twice what it did two years ago...a meal from the chip shop would cost me less than the food I prepare myself. I can afford to buy my vegies, but there would be a lot of people out there on a low income who couldn't.

Sometimes too, it seems to be sheer stupidity and this really saddens me. Relatives of mine are a perfect example. My aunt has a degree in human nutrition, and used to teach home ec. and health classes. She is grossly overweight, as are her two daughters. The elder (almost 21) weighs twice what I do, and the younger (16) isn't far behind. She's outweighed me since she was six years old All three have appalling eating habits, and my aunt and older cousin do no exercise whatsoever. I feel so sorry for these girls, because they've had these habits instilled in them from day one by somebody who ought to know better.

A year ago I would have said that genes have nothing to do with our weight but now I'd say they do play quite important role. According to this news article I've read in the local newspaper last year, genes in fact have some effect on whether we are thin or fat, if we smoke or not, if we are calm or aggresive, and even on our sexual activeness. I compared myself and my parents on all the traits mentioned (there were like 20 of them) and everything matched.

I think it can be either or both. There are definitely medical disorders that can cause and compound weight gain (or weight loss). Of course, it can also simply be caused by poor diet and lack of exercise. Or the two can compound each other.

As with many medical conditions, the caloric imbalance that results in obesity is probably the result of a combination of genetic and environmental factors. Polymorphisms (the existence of two or more different forms) in various genes controlling appetite, metabolism, and adipokine release(a pituitary hormone that mobilizes fat from adipose tissue) predispose to obesity, but the condition requires availability of sufficient calories, and other factors, to develop fully.

Therefore, while genetics may make it easier for certain people to become obese, lifestyle is the greater contributing factor.

BMI, or body mass index, is a simple and widely used method for estimating body fat. It is calculated by dividing the subject's weight by the square of his/her height, typically expressed either in metric or US "Customary" units:

Metric: BMI = kg / meters squared (meters x meters)

Example: a person weighing 70 kilos and 1.6 meters tall would have a BMI of 27.34. 70/(1.6*1.6)= 70/2.56= 27.34

US/Customary: BMI = lb * 703 / inches squared (inches x inches)

Example: a person weighing 180 pounds and 5' 8" tall would have a BMI of 27.36. (180*703)/(68*68)= 126540/4624= 27.36

The most commonly used definitions, established by the World Health Organization in 1997 and published in 2000, provide the following values:

A BMI less than 18.5 is underweight
A BMI of 18.5–24.9 is normal weight
A BMI of 25.0–29.9 is overweight
A BMI of 30.0–39.9 is obese
A BMI of 40.0 or higher is severely (or morbidly) obese

So, in our examples above, the individuals both fall into the "overweight" category and could probably stand to loose 6 kilos and 16 pounds respectively, based solely on BMI.

In a clinical setting, physicians take into account race, ethnicity, lean mass (muscularity), age, sex, and other factors which can affect the interpretation of BMI. BMI overestimates body fat in persons who are very muscular, and it can underestimate body fat in persons who have lost body mass (e.g. many elderly).

If you took an "average" height male (1.77m/5'9") the "normal" weight range would be 60 to 80 kilos or 125 to 175 pounds. Obesity would start at about 95 kilos or 210 pounds.

A better indicator of obesity is body fat percentage.

Body Fat Percentage Recommendations

Women

Age Underfat Healthy Overweight Obese
20-40 yrs Under 21% 21-33% 33-39% Over 39%
41-60 yrs Under 23% 23-35% 35-40% Over 40%
61-79 yrs Under 24% 24-36% 36-42% Over 42%

Men

Age Underfat Healthy Overweight Obese
20-40 yrs Under 8% 8-19% 19-25% Over 25%
41-60 yrs Under 11% 11-22% 22-27% Over 27%
61-79 yrs Under 13% 13-25% 25-30% Over 30%

While most people worry about their total weight, it would be more accurate to worry about the percentage of that weight carried as bodyfat.

To use our "average" male again, the same guy weighing 80 kilos/175 pounds; the high end of "healthy" going by BMI, is also healthier with a bodyfat percentage of 18% than 25%(obese by bodyfat percentages). At 25% bodyfat the guy would still need to drop another 5 kilos or 12 pounds to be a "healthy" weight of about 75 kilos/163 pounds. This is why I wish that people would be taught not only to watch their weight, but also bodyfat percent.

I would like to interject that I believe part of the weight problem today is the chemicals they use in the food. "Junk" like corn syrup instead of sugar. All those other 'phony' ingredients our bodies cannot recognize.

That's why I tell people keep away from diet food, nutrasweet, fake sugar, and so on.

Also, remember, cheap food is usually jam packed with preservatives. Buy a box of cheap cakes for less than $2.00...(you know snack cakes)....a mother can give each kid in her family 1 or 2...for $2.00 you get what, 2 apples???

Cost is a big fact. Go shopping sometime and just buy 'fruits and vegetables' and 'lean meats.' You will be very surprised how that adds up.

My kids are all "turfed out" to play after school and weekends/holidays but I know alot of people are over-protective of their kids now. There is no more risk of your children being abducted/murdered than there was 40 years ago, it's just it's sensationalised when it happens now so people are more aware of it. And my kids are all tall, skinny, healthy kids with appetites like horses!

I do think it is partly genetic as my eldest daughter is so skinny we can't find clothes or shoes to fit her properly, even though she eats more than her friends, my husband's sister and mum were the same when they were younger.
I have to agree here too, I don't buy processed foods and it is so expensive to feed my family of 5. My kids love fruit and I spend about £50 ($100) a week on fruit, we would have so much more money if I just fed them cakes and processed meals, but my children's health is more important.

Getting children into the habit of exercising is important too, my kids go to swimming and dancing lessons and do after-school sports when they are available. But I know some parents who work full-time and when they get home from work they don't want to be running around taking kids to clubs and activities, and although that's understandable I think you have to make an effort to do some kind of activities with them.

So, looking back at these comments, it's fair enough to believe that most people believe that our lifestyles has a substantial impact on our weight?

I think its our lifestyle. There is definitely an aspect of genetics involved, people are naturally all sizes... but the majority of us are getting fatter because we sit all day, and eat processed foods.

Some people naturally stay skinny, but that doesn't mean they're healthy. You can tell when you look at them. We're all being incredibly bad to ourselves.

I think it mostly genetic, actually. Obviously, you need to have food to get fat, so there is the environmental impact there. However, given that the Western lifestyle essentially allows people to be as active as they want, and eat as much as they want, then I think that genes play the bigger role in determining obesity in these areas.

Some people just don't enjoy exercise, and love to eat food. Some people just store fat more easily. With the same availability of food and exercise, some people are going to react differently and thus end up different sizes.


Actually, our body does recognise those ingredients. That is why they taste sweet. However, a sweet taste in the mouth sends signals to the brain (which sends signals to the metabolic organs) that a load of sugar is coming. When it doesn't arrive (because the product was sugar-free), your metabolism has to adapt. It usually can do this quickly, but prolonged exposure to sugar-free foods could cause cravings for real sugar - meaning more eating, and more weight gain.

But on the corn syrup point, I agree. Too much fructose, not enough glucose.

I really don't think obesity runs through human genes. It is, instead, applied by lack of activity and an increase in the average caloric intake. While some people do react differently to the same foods, no one's body is going to grow as large as a lounge-chair by eating a relatively healthy diet (raw fruit, vegetables, lean protein, mono and poly unsaturated fats).

Processed, fatty, sugary and outright preposterous foods are popping up everywhere, most appealing to kids, veiled by a shiny wrapper and a cute cartoon character.

Why to pop tarts come in packs of two when the serving size is one? Most kids will pop both in the toaster and chow down on 400 calories of sugar and saturated fat instead of eating a reasonable 200 calorie bowl of cereal with milk, enriched with vitamins and minerals.

Another factor our society places on the epidemic of obeisity is the ever-increasing lack of activity. Most kids today would rather stay indoors and play "Wii" or watch "Hannah Montana" on TV than go exploring outside or even go to the beach. As the kids of our generation grow older, their habits will stick with them and will eventually be passed on to their kids and so on.

As our society today places less of demand on physical labor, we need to pay attention to what exactly we are putting into our body and how it is going to effect us in the long run.

I'm poor (or rather, my family is poor). Poor people in developed countries have a tendency to be physically heavier than people who have a lot of extra disposable income. Healthy food is getting more expensive every day. So is it genetic or environmental? I think it's a little of both. I've found that when I bought the cheap, processed foods (all I could afford at the time), I gained a lot of weight and I didn't feel very good. Like a lot of things (at least in my own experiences), it comes down to cash, or the lack thereof.

So I'm giving serious thought to turning veg, even though my shift in diet would mean I would have to buy almost all of my own food, which would eat up all my own income. Just as a sort of experiment.

Oh, and to qualify? I'm 5'8" and BMI obese, and my mother is six inches shorter than me and weighs at least ten more pounds. My father and two younger brothers are thin as rakes, and superbly tall. And taking in the fact that most women have a tendency to keep weight (for fertility's sake), maybe it does have a distinct genetic variable for most people--male or female.

Call it sexist or classist. I don't care. Just my 2 cents.