Is WEIGHT GAIN caused by genetics or not? **For my Paper**

Xingy01

Point one: Genetics play a role in an individual’s “ideal weight,” not how much they gain.
Point two: Weight gain is caused by increased caloric intake; if you eat more than you burn, you gain weight, if you eat less, you lose it. Point three: Many people focus on blaming genetics when they do not want to put in the effort it takes to lose weight or to maintain weight loss.

I haven't done any scientific experiments but I'd be shocked if it was found that genetics wasn't a factor. It's true that it's calories in minus calories out but appetitite and body types are still genetic. And no, I'm not making excuses because I'm 5'11" 175 pounds.

Biochem grad here. I second this. Genetics definitely affects appetite, digestion, psychological components, and other contributing factors. Just because genetics doesn't directly cause weight gain doesn't mean that it isn't a significant influence. Most people accept that skin tone, hair color, and many other things are determined by genetics, but those things have environmental components as well. Just because there is an environmental component that you can somewhat control doesn't discount the fact that genetics matter.

loriemn

I think it's more "eating habits that get passed on from parents to offspring" than "genetics" that produce families and families of overweight people.

THIS for sure! I too think the way we eat is a learned behavior..and finally at the age of 47 I am relearning my bad habits!

ndj1979

How the hell are you going to tell me I haven't been at a deficit and I don't gain eating my TDEE when I log EVERYTHING I put in my mouth, weigh everything, wear a pedometer, wear a HRM when I'm working out?

Because you would be violating the laws of the universe if what you claim were true. It is *impossible* - you may as well be claiming you have a hammer that, when you drop it, floats in the air.

If your logging is telling you otherwise, there is something wrong with your logging - period. Full stop.

Sorry, but what I'm telling you is the truth.

the truth hurts….

EvanKeel

I've been at a deficit for the past 3 years and STILL gained weight because of my endocrine disorders.

You haven't been at a deficit.

I gain eating my TDEE

No, you do not.

LOL. How the hell are you going to tell me I haven't been at a deficit and I don't gain eating my TDEE when I log EVERYTHING I put in my mouth, weigh everything, wear a pedometer, wear a HRM when I'm working out?

I know what I do every day. You don't. So you are beyond ignorant. When you have spent years in and out of hospitals and doctors offices, seeing every specialist under the sun, having every test performed, having blood work every couple days, collecting 24 hr urine tests, undergoing MRIs, CT scans, x-rays, ultrasounds, colonoscopies, endoscopies, laparoscopies, cancer scares, etc. to find out why you've gained 100+lbs and experience the symptoms I do every day for NO REASON, THEN you can open your mouth. But until then, be quiet because your commentary isn't needed, wanted, or in any way helpful.

If you're gaining you have not...by definition...been eating at a deficit. The results determine whether or not you were eating at a deficit, eating your TDEE, or eating in a surplus, not a guess at what your TDEE should be. Estimates are just estimates regardless of your medical conditions.

Maleficent0241

I've been at a deficit for the past 3 years and STILL gained weight because of my endocrine disorders.

You haven't been at a deficit.

I gain eating my TDEE

No, you do not.

LOL. How the hell are you going to tell me I haven't been at a deficit and I don't gain eating my TDEE when I log EVERYTHING I put in my mouth, weigh everything, wear a pedometer, wear a HRM when I'm working out?

I know what I do every day. You don't. So you are beyond ignorant. When you have spent years in and out of hospitals and doctors offices, seeing every specialist under the sun, having every test performed, having blood work every couple days, collecting 24 hr urine tests, undergoing MRIs, CT scans, x-rays, ultrasounds, colonoscopies, endoscopies, laparoscopies, cancer scares, etc. to find out why you've gained 100+lbs and experience the symptoms I do every day for NO REASON, THEN you can open your mouth. But until then, be quiet because your commentary isn't needed, wanted, or in any way helpful.

I think you are misunderstanding what others are saying. I have a long and sordid medical history too. I have had so many scans I probably glow in the dark at this point - gained weight for "no reason". Finally got my metabolism tested and lo and behold, those calculators are very off for me and a "deficit" according to those was a surplus for me due to medical issues. It's not that your condition makes you gain weight while eating at a deficit (that is impossible), it's that your condition affects your TDEE (and BMR, RMR, etc.) to such an appreciable degree that you cannot rely on normal calculations to arrive at what your deficit actually should be.

Maleficent0241

OP -

I really hope you are just using this stuff as a jumping point and doing your own research as well. I won't go over issues with the thesis as others have already pointed that out, but a few leads for you to follow:

Research on the FTO genes, especially rs9939609
TAS2R38 gene and propensity to overeat
TMEM18 gene

neandermagnon

this isn't an English thesis question though... it's a biological sciences question.... scientists don't just dream up answers to these questions - they do research and studies, and it's all peer-reviewed. Asking people on the internet for their opinions is not valid research for this kind of question. Additionally, there's so much misinformation and confusion out there about questions like this and the main cause of the confusion and misinformation is non-scientists presenting their personal, uninformed, unresearched (or minimally researched) sometimes heavily biassed (including "cherry picked" research) opinions as fact. So I'm not just being pedantic about this being a biological sciences question rather than an English thesis question.

A thesis on this question needs to be based on peer reviewed research and it's going to have to be researched and written pretty much the same way that a biology student's thesis would read (okay, you can probably be a bit more relaxed in the writing style and style of referencing the studies, but you need to go to the biological sciences or similar department to do your research), if it's to have any benefit to humanity as opposed to adding to the confusion that's already out there.... it's not an opinion question, it's a research question.

Some pointers:

Yes weight gain is caused by genetics. 600 million years of animal evolution has resulted in genetics that cause animals to gain weight - usually fat but sometimes muscle, depending on the circumstances - when eating at a calorie surplus. It didn't have to be that way, I'm sure mutations arose along the way in animals whereby they were unable to store food if they ate in a surplus, maybe they just pooped it out, but natural selection didn't favour those individuals.... it favoured storing energy when they ate a surplus.

I know that's not what people mean by genetics, but that's actually the answer to the question. Yes weight gain is caused by genetics, and the reason why people gain weight when they eat more than the body needs is because the stored energy gives them a massive evolutionary advantage during a food shortage. And when the excess is stored as muscle, they have an evolutionary advantage by being stronger... yet too much muscle is a liability in a food shortage, hence why genes for muscle mass reduction during a food shortage or as a result of muscles not being used, has been selected for by natural selection.

Are some people genetically predisposed to be more likely to overeat or have a slightly slower metabolism or less lean mass and therefore gain weight more easily - Yes. There is variation in any population. People who naturally store more fat will survive best during a food shortage. In our evolutionary past, the situation where humans/animals can gorge themselves to the point of morbid obesity didn't occur, hence no evolutionary/genetic mechanism to prevent that. But as Homo sapiens, possibly the most intelligent species to have ever evolved, has enough cranial capacity to figure out it's a bad idea to do that.

Are there some genetic conditions which mean people gain weight too easily? Absolutely. Hypothyroidism, for example. And that's not necessarily genetic, because it can be caused by environmental factors. Genetic =/= factors beyond our control. Genetic = controlled by genes. Lots of factors beyond our control have nothing to do with genetics. I mention this, because people frequently talk about genetics in ways that imply they believe that if something's genetic it's beyond their control.... some things can still be controlled even though they're the result of genetics (e.g. you can still avoid weight gain with good portion control, even if you're genetically predisposed to gain weight more easily than average) and some things that can't be controlled are not the result of genetics but the result of environmental factors.

neandermagnon

If you have an endocrine disorder (PCOS, insulin resistance, diabetes, Hashimoto's, etc.), weight gain still happens even if the person is burning more calories than they are consuming.

No.

If that was the case, these bodies would have solved the world's energy problem by actually creating energy while starving themselves.

In these cases the body burns LESS, but people typically use a generic calculator which doesn't take account of their condition.

They don't realise that their body has a reduced BMR, so continue to eat more calories than their body needs.

The simplest way to work out deficit or surplus in such situations is to average out long term body weight tracking. If it's going up, you are in a surplus, not a deficit. You have more going in than coming out.

I've been at a deficit for the past 3 years and STILL gained weight because of my endocrine disorders. So don't tell me "no." You aren't a doctor. You don't have these disorders and you certainly don't know everything. It IS absolutely possible to gain weight when you are not in a surplus. That's what these disorders do to people. Talk to any endocrinologist. They'll tell you the same thing.

eating the number of calories that the calculators say should be a deficit =/= eating at a deficit

I totally believe you that your metabolism is slower than it should be, and so you're gaining weight while eating an amount of food that should be a deficit for anyone else your height and weight............. but if you're gaining weight you're not actually eating at a deficit. The calories in v calories out equation is still true. What's happening in your case is that your medical issues have skewed the calories out side of the equation, so you're gaining weight while eating less food than should cause weight gain

I know this sounds really pedantic, but please understand this point, otherwise you're going to be constantly annoyed with people telling you that you're not eating at a deficit. You're not. It's not your fault and no-one's accusing you of being a glutton or anything like that. They're just trying to explain the science.

ETA: trying to create a deficit in this situation by eating less and less can actually make the metabolic problem worse, so don't do that... it's better to create a deficit firstly by doing what you can medically to correct the metabolic issue (e.g. in the case of hypothyroid, take thyroid medication) as this puts the calories out side of the equation back to where it should be and makes it possible to eat at a deficit while eating normal healthy dieting amounts of food..... additionally it's also better to create a deficit by doing more exercise and still eating plenty of food. Exercise helps to speed up the metabolism. Eating less tends to cause the metabolism to slow even further.

geebusuk

For the people that claim they gain while eating at a TDEE.

No, I am not a doctor.
I DO however, understand the basic way world works in such situations.

As it goes, I do have a metabolic tester and have looked in to the area a bit.
How have you got your metabolism tested? If you have used an online calculator, but DO have issues, then the online calculator is wrong.
Despite having said metabolic tester (I'm not a very good salesman), I DO advise people that the best method to work out TDEE is CICO.

Taking from a poster above who gains on 1200 and loses on 800. If this happens consistently as an average over long periods, TDEE is probably somewhere around 1000 - certainly between the two. Of course, logging food isn't that accurate.
Many foods can be 50% unrepresented - suddenly a TDEE of 1500. HOWEVER, that doesn't matter. Because if they eat the up to a total of foods which claim to have 1000 calories and weight stays the same, that IS a useful TDEE number as it reflects their environment.

And I am happy to tell you, I was a stand-up comic for 15 years.

Then that's rather sad, to my mind. There does seem to be a trait in some stand ups that they can give it out, but not take it.
If you've been around stand ups for a good bit of time and STILL get offended by a joke which happens to hit home, then you definitely need a thicker skin, I'd say . (Appreciated British Stand Ups tend to be particularly offensive.)
So, yes, it IS about you having a thin skin, to my mind. Over the years I've been offended by many such things that could target me. Over the years I've realised I'd prefer the freedom of speech for people to say them than to restrict the things that personally offend me.

kassiebby1124

this isn't an English thesis question though... it's a biological sciences question.... scientists don't just dream up answers to these questions - they do research and studies, and it's all peer-reviewed. Asking people on the internet for their opinions is not valid research for this kind of question. Additionally, there's so much misinformation and confusion out there about questions like this and the main cause of the confusion and misinformation is non-scientists presenting their personal, uninformed, unresearched (or minimally researched) sometimes heavily biassed (including "cherry picked" research) opinions as fact. So I'm not just being pedantic about this being a biological sciences question rather than an English thesis question.

A thesis on this question needs to be based on peer reviewed research and it's going to have to be researched and written pretty much the same way that a biology student's thesis would read (okay, you can probably be a bit more relaxed in the writing style and style of referencing the studies, but you need to go to the biological sciences or similar department to do your research), if it's to have any benefit to humanity as opposed to adding to the confusion that's already out there.... it's not an opinion question, it's a research question.

Some pointers:

Yes weight gain is caused by genetics. 600 million years of animal evolution has resulted in genetics that cause animals to gain weight - usually fat but sometimes muscle, depending on the circumstances - when eating at a calorie surplus. It didn't have to be that way, I'm sure mutations arose along the way in animals whereby they were unable to store food if they ate in a surplus, maybe they just pooped it out, but natural selection didn't favour those individuals.... it favoured storing energy when they ate a surplus.

I know that's not what people mean by genetics, but that's actually the answer to the question. Yes weight gain is caused by genetics, and the reason why people gain weight when they eat more than the body needs is because the stored energy gives them a massive evolutionary advantage during a food shortage. And when the excess is stored as muscle, they have an evolutionary advantage by being stronger... yet too much muscle is a liability in a food shortage, hence why genes for muscle mass reduction during a food shortage or as a result of muscles not being used, has been selected for by natural selection.

Are some people genetically predisposed to be more likely to overeat or have a slightly slower metabolism or less lean mass and therefore gain weight more easily - Yes. There is variation in any population. People who naturally store more fat will survive best during a food shortage. In our evolutionary past, the situation where humans/animals can gorge themselves to the point of morbid obesity didn't occur, hence no evolutionary/genetic mechanism to prevent that. But as Homo sapiens, possibly the most intelligent species to have ever evolved, has enough cranial capacity to figure out it's a bad idea to do that.

Are there some genetic conditions which mean people gain weight too easily? Absolutely. Hypothyroidism, for example. And that's not necessarily genetic, because it can be caused by environmental factors. Genetic =/= factors beyond our control. Genetic = controlled by genes. Lots of factors beyond our control have nothing to do with genetics. I mention this, because people frequently talk about genetics in ways that imply they believe that if something's genetic it's beyond their control.... some things can still be controlled even though they're the result of genetics (e.g. you can still avoid weight gain with good portion control, even if you're genetically predisposed to gain weight more easily than average) and some things that can't be controlled are not the result of genetics but the result of environmental factors.

I know it's science-based. It's just an argumentative research paper for my English class. I'm speaking more in terms that people who don't have any medical issues blame genetics, though it is extremely helpful and makes sense to put in some people who do have those problems. My professor told me to pick something I'm passionate about and I guess this hit home for me because of the number of people I know blaming their genetics for why they're fat versus doing anything about it.

JamesRustler

littlekitty3

Weight gain and genetics are not related, bad diet and poor habits can result in weight gain.

Also there are studies (I don't have the specific link bookmarked but you could probably find it) that we all have a similar basic metabolic rate...I mean obviously 100lb vs 200lb person is going to have a different caloric intake but their rate will be the same.
Here's where it gets tricky.....2 people weighing the same, same gender, same height, same body mass of muscle and fat ect. Will their metabolism be the same? Probably not. Majority of the population may be in a range of 200 calories below or above the medium or 10%. There's 1% of the population who will go at least double that amount above or below .

emstethem

I don't think it's genetics...everyone (EVERYONE) in my family is fit and takes care of themselves...but I'm overweight...because I'm lazy...I'm working on it though which is why I'm here...

psuLemon

If you have an endocrine disorder (PCOS, insulin resistance, diabetes, Hashimoto's, etc.), weight gain still happens even if the person is burning more calories than they are consuming.

No.

If that was the case, these bodies would have solved the world's energy problem by actually creating energy while starving themselves.

In these cases the body burns LESS, but people typically use a generic calculator which doesn't take account of their condition.

They don't realise that their body has a reduced BMR, so continue to eat more calories than their body needs.

The simplest way to work out deficit or surplus in such situations is to average out long term body weight tracking. If it's going up, you are in a surplus, not a deficit. You have more going in than coming out.

I've been at a deficit for the past 3 years and STILL gained weight because of my endocrine disorders. So don't tell me "no." You aren't a doctor. You don't have these disorders and you certainly don't know everything. It IS absolutely possible to gain weight when you are not in a surplus. That's what these disorders do to people. Talk to any endocrinologist. They'll tell you the same thing.

Have you gotten any metabolic testing done? Also, with your condition, do macronutrients play a bigger role? I know with my wife's condition, she is gluten and carb sensitive and has struggle with energy levels and weight loss. Now that she has gotten away from a lot of carbs, she is slowly making improvements such as being able to workout for the first time in over 10 years without getting dizzy or passing out.

cheddar2000

This is from the Coriell Institute for Medical Research - they do genetic testing and I am one of the early volunteers:

"Genetic vs. Non-Genetic Risk Factors
Obesity is caused by eating more calories than are used in physical activity. The risk of becoming obese is influenced by both genetic factors and non-genetic (or environmental) risk factors.

It is estimated that non-genetic factors (like diet and exercise) account for about 14% of the risk of becoming obese.

It is estimated that 86% of the risk of becoming obese is based on genetic risk factors. This estimate accounts for both known and unknown gene variants."

psuLemon

Point one: Genetics play a role in an individual’s “ideal weight,” not how much they gain.
Point two: Weight gain is caused by increased caloric intake; if you eat more than you burn, you gain weight, if you eat less, you lose it. Point three: Many people focus on blaming genetics when they do not want to put in the effort it takes to lose weight or to maintain weight loss.

I haven't done any scientific experiments but I'd be shocked if it was found that genetics wasn't a factor. It's true that it's calories in minus calories out but appetitite and body types are still genetic. And no, I'm not making excuses because I'm 5'11" 175 pounds.

Biochem grad here. I second this. Genetics definitely affects appetite, digestion, psychological components, and other contributing factors. Just because genetics doesn't directly cause weight gain doesn't mean that it isn't a significant influence. Most people accept that skin tone, hair color, and many other things are determined by genetics, but those things have environmental components as well. Just because there is an environmental component that you can somewhat control doesn't discount the fact that genetics matter.

But you can't confuse environmental factors as part of genetics. If it genetic, then it means you are predisposition to have that destiny. Would you suggest that a person is predisposed to being overweight? I understand that medical conditions make things difficult and can throw a wrench into things until it's properly diagnosed and medicated, but regardless of the condition, you can be skinny or obese. It just depends on finding the right combination of medical and diet that works.

perseverance14

Thyroid disease is 10% of the population (talking USA here) and before I was on meds, I was gaining weight and there was nothing I could do to stop it, no matter how I ate or how much I exercised. There is a lot of undiagonsed conditions (it took me many years to get my diagnosis from when I first had symptoms, about 20), thyroid disease, diabetes, etc.

neandermagnon

Point one: Genetics play a role in an individual’s “ideal weight,” not how much they gain.
Point two: Weight gain is caused by increased caloric intake; if you eat more than you burn, you gain weight, if you eat less, you lose it. Point three: Many people focus on blaming genetics when they do not want to put in the effort it takes to lose weight or to maintain weight loss.

I haven't done any scientific experiments but I'd be shocked if it was found that genetics wasn't a factor. It's true that it's calories in minus calories out but appetitite and body types are still genetic. And no, I'm not making excuses because I'm 5'11" 175 pounds.

Biochem grad here. I second this. Genetics definitely affects appetite, digestion, psychological components, and other contributing factors. Just because genetics doesn't directly cause weight gain doesn't mean that it isn't a significant influence. Most people accept that skin tone, hair color, and many other things are determined by genetics, but those things have environmental components as well. Just because there is an environmental component that you can somewhat control doesn't discount the fact that genetics matter.

But you can't confuse environmental factors as part of genetics. If it genetic, then it means you are predisposition to have that destiny. Would you suggest that a person is predisposed to being overweight? I understand that medical conditions make things difficult and can throw a wrench into things until it's properly diagnosed and medicated, but regardless of the condition, you can be skinny or obese. It just depends on finding the right combination of medical and diet that works.

People can be genetically predisposed to overeating through malfunction in the body's appetite regulation systems, i.e they never get the "full" signal when they've eaten enough so are prone to overeating. This can also happen due to damage to the hypothalamus, i.e it's not genetic it's environmental, but it still causes the person to have a tendency to overeat.

To some extent humans in general have a tendency to overeat, probably because Homo erectus didn't have a guaranteed food supply and thus people who overate when there was plenty of food and stored up fat for leaner times came through food shortages better and thus left more genes in the population. We're all the descendents of generation upon generation of people who survived food shortages - we're adapted for surviving in an environment where food was sometimes scarce and food always required effort (sometimes very strenuous effort) to acquire, not for living in a world where you can order pizza and mcdonalds over the telephone to be delivered through your living room window without even leaving the sofa. And if something is the result of natural selection, then it does come from genetics, because genes are what are passed from generation to generation and what natural selection acts upon. And when something comes from genes, there is nearly always variation. So there is definitely genetic variation in the extent to which people are predisposed to overeat. And that includes some people being predisposed to undereat - i.e. the "hard gainers" who do all kinds of weight lifting programmes and try their best to eat at a surplus but still don't gain weight because their appetite set point won't let them (and trying to eat more when you're full to the point of nausea is something no-one can do very easily).

This question is a highly complex one, and the issue of people thinking that they're the only one that finds fat loss difficult and that maintenance of a healthy weight requires effort and vigilance, or that being like this is abnormal and everyone else finds it easy, is not the same as the question as to whether some people are genetically predisposed to get fatter more easily than others.

However, going back to the OP's aim in this - whether someone's genetically predisposed to overeat more than average, that does not condemn them to a lifetime of obesity.... the obesity can be overcome through exercise and portion control (for someone prone to overeating, then exercise is probably even more important)........... the myth that "I have a genetic tendency to obesity therefore there's nothing I can do about being obese" is probably what needs to be challenged the most. Just because you're genetically predisposed to something doesn't mean it's impossible to mitigate that thing through controlling the environmental factors that interplay with the genetic factors. In the case of obesity that means ensuring an active lifestyle and good portion control.

RHachicho

Look guys you both are right.

It's true that genetics don't really forbid you from getting the body you like. And it's true that a lot of people use their genetics as an excuse never to try. It's also true that some people don't CARE that they are overweight. And just use the word genetics to get dieting Nazi's off their back. This isn't the kind of question with a simple either or answer. It depends on the circumstances. And yes while genetics can give you certain predispositions in the end how you end up is up to you. It's also true that how our parents teach us to eat effects our metabolism and our perception of food at the fundamental level. Which can in certain cases create disastrous metabolic trends. Which can be very difficult to beat later in life.

So long story short yeah encourage people to lose weight but you know what If they don't want to then get off their back. Not everyone has to be a healthy weight if they don't want to. People do unhealthy things because they are fun ALL the time. Now I'm not advocating just allowing someone to succumb to true excess. But honestly if someone wants to be 50lb or even 100lb over what you would consider healthy weight and they don't have a problem with it it's your lookout to accept that not theirs to change.

And to the OP honestly you shouldn't ask a question like that on a forum like this. Almost every one here is an avid dieter. You should have expected this level of soap boxing. If you really want to write a paper on this issue then you need to explore much more then genetics to account for eating and weight trends. In that respect it's true that genetics doesn't really play much of a role. But to say it plays none? Kinda naive too.

psuLemon

People can be genetically predisposed to overeating through malfunction in the body's appetite regulation systems, i.e they never get the "full" signal when they've eaten enough so are prone to overeating. This can also happen due to damage to the hypothalamus, i.e it's not genetic it's environmental, but it still causes the person to have a tendency to overeat.

To some extent humans in general have a tendency to overeat, probably because Homo erectus didn't have a guaranteed food supply and thus people who overate when there was plenty of food and stored up fat for leaner times came through food shortages better and thus left more genes in the population. We're all the descendents of generation upon generation of people who survived food shortages - we're adapted for surviving in an environment where food was sometimes scarce and food always required effort (sometimes very strenuous effort) to acquire, not for living in a world where you can order pizza and mcdonalds over the telephone to be delivered through your living room window without even leaving the sofa. And if something is the result of natural selection, then it does come from genetics, because genes are what are passed from generation to generation and what natural selection acts upon. And when something comes from genes, there is nearly always variation. So there is definitely genetic variation in the extent to which people are predisposed to overeat. And that includes some people being predisposed to undereat - i.e. the "hard gainers" who do all kinds of weight lifting programmes and try their best to eat at a surplus but still don't gain weight because their appetite set point won't let them (and trying to eat more when you're full to the point of nausea is something no-one can do very easily).

This question is a highly complex one, and the issue of people thinking that they're the only one that finds fat loss difficult and that maintenance of a healthy weight requires effort and vigilance, or that being like this is abnormal and everyone else finds it easy, is not the same as the question as to whether some people are genetically predisposed to get fatter more easily than others.

However, going back to the OP's aim in this - whether someone's genetically predisposed to overeat more than average, that does not condemn them to a lifetime of obesity.... the obesity can be overcome through exercise and portion control (for someone prone to overeating, then exercise is probably even more important)........... the myth that "I have a genetic tendency to obesity therefore there's nothing I can do about being obese" is probably what needs to be challenged the most. Just because you're genetically predisposed to something doesn't mean it's impossible to mitigate that thing through controlling the environmental factors that interplay with the genetic factors. In the case of obesity that means ensuring an active lifestyle and good portion control.

I guess my definition may be a bit too black and white. The way I have looked at is, even if you have a medical condition, do you still have the ability to lose weight? If so, then it isn't a genetic issue, but rather environmental. To me environmental =/= genetic; I more see that as a variable. So I guess that question would be how the scientific community views genetic factors, which I would have to investigate more.

I view it this way because when I think genetics (eye color, skin color, bone structure, blood type) those are all things you cannot change (outside of surgery). And weight is something that can change.