The genetic basis of obesity

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Obesity. It's a global epidemic that now kills more people than malnutrition. Physiologists work to unravel the causes of obesity and the genetic factors involved.
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Produced by Orinoco Communications for The Physiological Society
Animation: Hayley Evenett
Illustration: Alex Scarfe
Sound Design/Music: Alexander Bradley
Narration: Elisa Canas
Director: Peter Barker
Scientific advisor: Jeffrey M Friedman
Producer at The Physiological Society: Rachel Wheeley
Transcript:
Sometimes it seems like everywhere we look we’re exposed to adverts about dieting, urging us to lose weight.
Globally, the diet industry rakes in over £150 billion a year, and that figure is rising fast.
But, at the same time, worldwide obesity levels are also growing, and that matters, because obesity now kills more people than malnutrition.
So, what’s going on? Why are self-control and dieting alone unable to stop the growing obesity epidemic?
Research by physiologists suggests there are important biological factors at play.
Namely, that some of us are simply more genetically predisposed to become obese than others.
The root causes of obesity can be summed up like this: food intake, minus energy burned, equals fat stored.
So, obesity occurs when we consume more than we burn, and fat mass builds up.
But what happens when genetics are thrown into the mix?
Our understanding of this field has been advanced by scientific experiments involving a species of obese mouse.
These mice are always hungry and won’t stop eating. They never feel full.
The mice weigh three times more than normal mice because of a defect in a single gene.
Scientists identified that gene as one that codes for a hormone called leptin.
Leptin is made by fat cells and signals to the brain how much fat mass is in the body.
Without it, the brain mistakenly believes the body is starving, so the mice keep eating, even though they’ve had enough food.
Scientists translated this finding to humans when a four-year-old boy with the same genetic mutation became severely obese.
With regular leptin injections, his over-eating stopped and, by the age of eight, he was no longer overweight.
Studies of twins have helped us to identify the genetic basis of obesity.
Identical twins who come from the same egg and the same DNA have very similar body sizes.
But twins that come from different eggs show much more variability.
These studies show that while single genes are occasionally responsible most obesity cases are caused by a combination of genes working together.
Understanding the causes of obesity is far from simple but genetic factors such as leptin play an important role to regulate food intake and body weight.
So self-control alone is rarely enough to overcome the powerful effect of genes.
That’s why physiologists are working hard to assess how a healthy diet and exercise, combined with a better understanding of how genes influence obesity, can help turn the tide on this global epidemic.

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29 ноя 2020

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Комментарии : 186

@adamwilliams5372 Год назад

I don't buy into people carrying weight in all instances because they hide calories or don't train. I have a careful balanced diet and I train sometimes twice a day but everyday. Sometimes 2 or 3 hiit or bootcamps in a day. 3 dog walks and play football as well as swim 60 lengths a few times a week. I have belly fat I can't shift. My parents both had the same issue. My calorie intake is around 2500 because I train a lot. When I lower it I'm tired and can't train as hard. But it's annoying

@henrybird26 Год назад

I think when you focus and blame, obesity on one characteristic, such as genetics You lose your objectivity, and as a result, you lose focus on the problem.

@EvieBelieveMe 5 месяцев назад

It’s not blame, it’s understanding. That’s like saying don’t blame the fact you can’t breathe under water on genetics lol

@GoodDr. 2 месяца назад

We need policies that support healthy living, from schools to workplaces to communities

@Asus_sugoma 2 месяца назад

The video didn't claim that obesity could be explained by genetics,it claimed that genetics is *a factor* that influences hunger and therefore influences food intake and therefore can indirectly lead to obesity when there are enough calories available. It did not claim that the increase in obesity was due genetic mutations,but explained that genetics is *one* of the factors that can contribute to obesity.

@kezmenflowers8691 2 месяца назад

Ive always struggled with obesity ever since i was a kid because i was more susceptible to it than the rest of my family and yet im more active and have done way much more than my family has. There can be genetic differences even though you do come from the same family. I also come from parents that were addicts also, so i had to overcome drug and alcohol addiction and just got rid of eating highly processed sweets. So i dont want to hear people say its because im lazy because i am very active and do move a lot but yet i see people who are chain smokers and alcoholics who are based on society standards healthy looking and yet i dont drink nor do drugs but just because im overweight i get harshly judged and devalued because of how i look. F you society.

@mattias9411 3 года назад

What prevalence does this mutation have?

@WorthlessWinner 3 года назад

Not sure if the focus on leptin is appropriate as, even with the "rarely due to a single gene" disclaimer, it can perpetuate the myth that something has to be Mendelian to be 'genetic'

@girlgonewoof Год назад

Yeah, I did DNA testing and it showed that I have this "obesity" gene, but my BMI is 19 and I'm not restricting my eating at all, just eat somewhat healthy. So it's not all about genes.

@WorthlessWinner Год назад

@@girlgonewoof - there are some mutations that have a big effect on traits, but those tend to be rare; if the effect is large and bad then it will be strongly selected against and only few people will have it. Some Mendelian mutations do exist for obesity (e.g. those causing Prader-Willi syndrome). As a result of the rarity of mutations of large effect, you need to look at 100s of mutations to get a good idea of your actual genetic risk, using something like a poly-genic score; the DNA testing companies like 23andme usually just tell you about the 1 mutation of largest effect, which likely has small effects. Even mutations in the same gene can have different effects; those that totally prevent expression of a gene could always cause a disease, while those that only decrease expression or activity cause a slight increase in disease, or a totally different disease. The gene for Prader Willi can, if mutated in the opposite direction, cause angelman syndrome (similar to anorexia), and if mutated in a smaller way causes neither condition. Twin, adoption and family studies suggest BMI, in the current population, is about as genetic as intelligence, schizophrenia or height, (80-90%) but is not entirely genetic. However, DNA based estimates of heritability are much lower, likely just because we haven't found all the responsible genes yet (most studies only look at genes present in over 1% of the population, only in the last 5 years have we moved beyond that and rapidly started explaining more variation). So with all the known genes added together we can only predict about 10-20% of variance in BMI from DNA at present. I think it is less that "environment is important" and more that "our genetic predictions are really bad at present." Then again, twin and adoption studies give heritability for a specific environment; in developed countries it is 80-90% but in poor countries it is as low as 20 to 30% because there is a lot more environmental variation in those countries. So it is possible some environment that is currently rare would be very important if people were exposed to it, but they just aren't being exposed to it yet.

@saulwilliams-wilson7356 2 года назад

but obesity is a relatively new phenomena. have our genes changed so fast?

@rd-lw4td 2 года назад

Yeah, I think the genes that cause obesity are rare. It makes sense that we have an obesity epidemic with all the terrible foods around us. We also don't do as much physical labor as we did in the past.

@BiggieTurms 2 года назад

I think the video confuses this genetic mutation with the widespread obesity we see today. Some people have this mutation which causes them to eat way too much but this is rare, there are documentaries on people with this. I think obesity in general is not caused by genes but rather overeating, unhealthy foods and lack of exercise. Even if it was caused by a lack of feeling full it should be a relatively easy problem to fix, know your portions and stick to it. Simple.

@Kane6676 2 года назад

No it isn’t, you can find pictures of fat people going back for 100 years or more. Also good is much much more available now so more people are fat. Not everyone is genetically fat, some just eat too much and don’t move enough. Yep different things

@WeatherMondacicci 2 года назад

@@Kane6676 It's been around for as long as we have been here. The Women of Willandorf figure is proof of that and that is not the only obese statuette that they found. I believe that obesity is largely genetic and it makes sense.

@Kane6676 2 года назад

@@WeatherMondacicci you are right it is. I grew up with cousins who could eat ten boxes of twinkies followed by a six pack of coke daily an so never gain weight

@rohinisivamurthy5279 2 года назад

This is confusing. I have come across people who eat more than an over weight person and does no exercises yet still stay thin. I feel some kind of metabolic gene or a fat burning gene in them keeps burning all the fat 24/7 no matter how much they eat.

@rd-lw4td 2 года назад

Fat person is hiding their calorie intake. Our metabolism doesn't vary that much.

@phantless2203 2 года назад

@@rd-lw4td i does though some people can eat more than fat people and gain nothing

@rd-lw4td 2 года назад

@@phantless2203 yeah, people who are more active and muscular like me. If I stopped, I'd gain weight if I didn't adjust my diet.

@josephujoostaa4462 2 года назад

Theyre naturals, their mitochondrial function is high, so their bodies use the nutrients better, so they dont get fat.

@rd-lw4td 2 года назад

@@josephujoostaa4462 horseshit. They're not admitting the garbage they eat. Just look at the crap people are eating.

@SportOffice 3 года назад

excellent video

@messykitchen7 9 месяцев назад

Amazing

@leoalphaproductions8642 3 года назад

I’m pretty sure I have obesity issues. I gain weight rapidly if I’m not working out or on a proper diet. Also I have issues where I’m always hungry if I’m not eating the right food. I cut out carbs and sugars 2 years ago, and now all I eat is meat. The fat practically melted away within months and I wasn’t even that active. Now I have an average BMI and I’m healthier than most people. Also didn’t have any hunger issues either. I think those carbs and sugars have some real physiological effect that just keeps you hungry and fat.

@rd-lw4td 2 года назад

Protein fills us up. Carbs are going to give you energy for working out, so I wouldn't completely cut them out. Just don't eat a surplus of what you need. It's easy to have a messed up diet from the choices we're giving.

@leoalphaproductions8642 2 года назад

@@rd-lw4td it’s the fat that satiates you. I’ve had days where I’ll eat lean meat like a lean piece of steak or a chicken, and I’ll feel very hungry afterwards. Once I add some animal fats like butter or eat a fatty piece of steak, I’ll feel completely satiated - even up until the next day. I find that if I eat carbs I feel low energy during my workouts. Some of my most explosive workouts I’ve had have been on low/zero carbs. I think being fat adapted is overall better for workouts. Plus you’ll have more energy. When I eat carbs, I’m always low energy and feel almost depressed during workouts. It sucks. Surprisingly, my brain function is more clear and faster when I’m fat adapted too. Also, your body doesn’t require glucose. There’s already a process that creates glucose in your body - it’s called gluconeogenesis. It occurs through oxidation of fatty acids, which produces glucose in your body to help the organs that need it to function. If you have an exogenous source of glucose, that can lead to a lot of health problems in the future. Diabetes being one of them, as well as many other problems.

@rd-lw4td 2 года назад

@@leoalphaproductions8642 well, fat does too. You certainly need protein, fat, and carbs. The fat does help you stay full. Fiber also helps and slows carbs down.

@rd-lw4td 2 года назад

@@leoalphaproductions8642 "I find that if I eat carbs I feel low energy during my workouts. Some of my most explosive workouts I’ve had have been on low/zero carbs" It's probably from carbs the day before. You need them for energy. You use up carbs in your workout, so if you eat the right amount you will not gain any weight from them. If you eat too many carbs, you do feel lethargic. Just got to eat the right amount. Yesterday, I ate an apple for energy before working out. If you feel tired during a workout, you can use simple carbs for energy as well.

@leoalphaproductions8642 2 года назад

@@rd-lw4td what do you mean from carbs the day before? These were instances where I’ve gone without carbs for months. Every now and then I’ll have a bit of carb after a few months, but then I feel like crap afterwards - then have to go back into ketosis. Then I’m fine again. That’s why I try to avoid carbs. They’re really not good for me. I don’t need fibre either. I’ve been doing fine without it. There’s actually never been any randomized control trials on the efficacy of fibre. The stuff you hear about fibre is always conjecture that’s never backed up by any mechanistic data. In fact, what little evidence we do have shows that fibre actually makes constipation worse, because it tends to block the passage of the colon. It’s practically indigestible matter that your body has no use for.

@dianapreisser2146 10 месяцев назад

Good video but the music was too loud

@nealwright5630 Год назад

Watch videos of the sixties and earlier and then rethink this.

@sarahmauser3687 2 года назад

is it?

@new_life_wellness 6 месяцев назад

good

@MrBeard-ig5zc 2 года назад

Nobody was far 100 years ago. It's not genetic.

@fatoumattatouray5844 2 года назад

That's a wrong and stupid claim. Just look at paintings of people from a hundred, even a thousand years ago. There were always fat people.

@mrs.g.35 2 года назад

This is beyond stupid. Of course people were still fat even 1000s of years ago. The Bible even has a story of a fat king so big that his belly fat "swallowed" the knife when he was stabbed. Less people were fat due to lower easy availability of calorie dense food, and an increase in daily physical labor.

@rd-lw4td 2 года назад

@@fatoumattatouray5844 yeah but not 40% of them.

@seansezz 2 года назад

There have always been fat people

@WeatherMondacicci 2 года назад

@@rd-lw4td There were fat people back then.

@the_truthdealwithit4217 Год назад

Bull!!! Have some self control and eat healthy and exercise. Obesity is not a disease, its a lack of self control & self pride! Make living healthy a lifestyle and stop making excuses!!!!

@julianbatiste5997 2 года назад

When around my father I just want to give up at life and just die, he has never worked a day in his life, he a crack head/drug head, he very unhealthy, he never supported me, he blames his problems on everyone else, he has full common sense but refuses to use the brain god gave him, he calls everyone the devil who’s doing better then him, he says in order to be successful you have to give your soul to satan, hes a leach, he’s 50 and still lives with his mother but his father was a very successful man (he was a boss and owned business) my father has more then a hundred lazy bones in his body, I’m 20 Nd black of color what I inherited from him walking into man hood was bad hygiene, bad health, I never peaked, missing teeth, doubt that I will be somebody and confusion on how to be a man / my mom is a hardworking mother and father and what I inherited from my mom was to never give up no matter how bad my situation is and a hardworking work ethic on the job and positive mindset off the job

@kajal-jz6br 3 месяца назад

Stholyantak Churna by Planet Ayurveda is a unique Ayurvedic herb that is effective in weight loss.

@dlaregleyar 10 месяцев назад

"To lose weight, eat low carbs only. Avoid rice, sugar, pasta, soft drinks, and bread. Opt for avocado or berries as your fruit choices. For protein, consume any meat, eggs, chicken, or fish. Stick to leafy green vegetables for your vegetable intake. Additionally, include walking exercises and fasting to expedite weight loss. Consider drinking 1 liter of water with 1 teaspoon of salt as an electrolyte supplement. This will help maintain proper hydration and mineral balance in your body."

@albin4323 29 дней назад

The average person today weights 30 pounds more despite the same calori intake and height compared to the average person who lived in the 80's, persevatives, chemicals and change in gut bacteria is the blame.

@rogerluffy422 2 года назад

My whole family from my mothers side has been fat and nothing used to work on my health until i got to know about Ayurvedic medicine which i took from Planet Ayurveda and that had led me to a perfectly healthy life

@GardensoftheAncientsHerbal Год назад

So it’s not that genetics per se make you fat but influence your habits and impulse….

@Kevork1970 10 месяцев назад

Yeah maybe also mention the billions spent on advertising fast food?

@1987dfa 2 года назад

Obesity is directly related to food. The evidence is that we determine our metabolic rates through activity in our development years. All people when starved lose mass and eventually die. Let's not complicate basic science and observation here. I am not doubting that genetics may make losing weight more difficult - in which case it is the responsibility of the individual to manage diet accordingly, just as a top athlete would intake less calories in retirement...

@1987dfa 2 года назад

@Martin Pospisil never an intention to shame at all. The problem is, the truth can be hurtful. I have many flaws and own them, If I snack throughout the week I expect a 5lb increase in weight. Will power is not genetic and it I a mindset choice of choosing wellbeing over craving. Self discipline. Self control. For example, I could not justify punching someone I hate in the face and put it down to genetic urges. The Liberal era has effed up everything as people pick and choose where an argument suits.

@1987dfa 2 года назад

@Martin Pospisil I do something very similar. Since I finished playing sports I don't eat breakfast and eat a meal at 5pm and a small snack at 8pm. Technically a 20ish hour fast per day!

@1987dfa 2 года назад

@Martin Pospisil the body becomes more efficient too

@rd-lw4td 2 года назад

@@1987dfa if you eat a high protein breakfast, you boost your metabolism. Eat properly.

@1987dfa 2 года назад

@@rd-lw4td not necessarily!

@somlomomhlahlandlela6084 2 года назад

the feebleminded of the 21st century are the obese, Eugenics 2.0 why do these researchers not talk about obesity in societies that have pretty much have had the same diet for 1000s of years e.g Amazonian nations, Khoisan, Himba nation, or rural Africa in general,,,, if there's an obesity gene, guess there's malnutrition gene too EUGENICS never died, it changed its name to Genetics

@MaximDavinchki 2 года назад

Back then in the 70s and 80s obesity wasn‘t as common as nowadays.

@alex-dn9to 2 года назад

more physical activity is needed sports make them do it!

@MrSteveyz Год назад

How about do a year of rigorous exercise, and being disciplined about it. Don't skip any days. Don't falter. On top of eating super healthy every day for that year first. Then tell me about your genetics.

@---bh8jq 3 года назад

Excuses!!

@Asus_sugoma 2 месяца назад

1-The video is not defending a moral thesis,like the thesis that we shouldn't judge an obese person discipline and character because their eating behavior is reducible to genetics,it instead is stating a fact,the fact that genetics is an indiretc contributing factor due to its influence on hunger 2-The video did not say that genetics is the cause of obesity,it said it is a contributing factor. 3-Genetics that increase your hunger hormones will increase your food intake when there is enough food available,and therefore will increase your weight. That is basic logic 4-Why are you treating obesity like it was a crime that could be "excused" or punished?