Slim people have a genetic advantage when it comes to maintaining their weight
January 24, 2019
Science Daily/University of Cambridge
In the largest study of its kind to date, researchers have looked at why some people manage to stay thin while others gain weight easily. They have found that the genetic dice are loaded in favor of thin people and against those at the obese end of the spectrum.
More than six in ten adults in the UK are overweight, and one in four adults is obese. By age five, almost one in four children is either overweight or obese. Excess weight increases the risk of related health problems including type 2 diabetes and heart disease.
While it is well known that changes in our environment, such as easy access to high calorie foods and sedentary lifestyles, have driven the rise in obesity in recent years, there is considerable individual variation in weight within a population that shares the same environment. Some people seem able to eat what they like and remain thin. This has led some people to characterise overweight people as lazy or lacking willpower.
With support from Wellcome and the European Research Council, a team led by Professor Sadaf Farooqi at the Wellcome-MRC Institute of Metabolic Science, University of Cambridge, established the Study Into Lean and Thin Subjects -- STILTS -- to examine why and how some people find it easier to stay thin than others. Studies of twins have shown that variation in body weight is largely influenced by our genes. To date studies have overwhelmingly focused on people who are overweight. Hundreds of genes have been found that increase the chance of a person being overweight and in some people faulty genes can cause severe obesity from a young age.
Professor Sadaf Farooqi's team were able to recruit 2,000 people who were thin (defined as a body mass index (BMI) of less than 18 kg/m2) but healthy, with no medical conditions or eating disorders. They worked with general practices across the UK, taking saliva samples to enable DNA analysis and asking participants to answer questions about their general health and lifestyles. It is thought to be the only cohort of its kind in the world and the researchers say that the UK's National Institute for Health Research -- the National Health Service's research infrastructure -- strongly enabled and supported their research.
In a study published today in the journal PLOS Genetics, Professor Farooqi's team collaborated with Dr Inês Barroso's team at the Wellcome Sanger Institute to compare the DNA of some 14,000 people -1,622 thin volunteers from the STILTS cohort, 1,985 severely obese people and a further 10,433 normal weight controls.
Our DNA comprises of a sequence of molecules known as base pairs, represented by the letters A, C, G and T. Strings of these base pairs form genetic regions (which include or make up our genes). Our genes provide the code for how our body functions and changes in the spelling -- for example, a C in place of an A -- can have subtle or sometimes dramatic changes on features such as hair colour and eye colour but also on a person's weight.
The team found several common genetic variants already identified as playing a role in obesity. In addition, they found new genetic regions involved in severe obesity and some involved in healthy thinness.
To see what impact these genes had on an individual's weight, the researchers added up the contribution of the different genetic variants to calculate a genetic risk score.
"As anticipated, we found that obese people had a higher genetic risk score than normal weight people, which contributes to their risk of being overweight. The genetic dice are loaded against them," explains Dr Barroso.
Importantly, the team also showed that thin people, had a much lower genetic risk score -- they had fewer genetic variants that we know increase a person's chances of being overweight.
"This research shows for the first time that healthy thin people are generally thin because they have a lower burden of genes that increase a person's chances of being overweight and not because they are morally superior, as some people like to suggest," says Professor Farooqi. "It's easy to rush to judgement and criticise people for their weight, but the science shows that things are far more complex. We have far less control over our weight than we might wish to think."
Three out of four people (74%) in the STILTS cohort had a family history of being thin and healthy and the team found some genetic changes that were significantly more common in thin people, which they say may allow them to pinpoint new genes and biological mechanisms that help people stay thin.
"We already know that people can be thin for different reasons" says Professor Farooqi. "Some people are just not that interested in food whereas others can eat what they like, but never put on weight. If we can find the genes that prevent them from putting on weight, we may be able to target those genes to find new weight loss strategies and help people who do not have this advantage."
https://www.sciencedaily.com/releases/2019/01/190124141538.htm
Treating obesity: One size does not fit all
November 13, 2018
Science Daily/Brown University
Understanding the very different characteristics of subgroups of obese patients may hold the key to devising more effective treatments and interventions, new research found.
Analyzing data from more than 2,400 obese patients who underwent bariatric weight-loss surgery, researchers identified at least four different patient subgroups that diverge significantly in eating behaviors and rate of diabetes, as well as weight loss in three years after surgery.
"There probably isn't one magic bullet for obesity -- if there is a magic bullet, it's going to be different for different groups of people," said Alison Field, chair of the department of epidemiology at the Brown University School of Public Health and lead author of the paper.
"There's a really diverse mix of people who get put into one group. A child who becomes very obese by age 5 is going to be very different from someone who gradually gains weight over time and at age 65 is obese. We need to recognize this diversity, as it may help us to develop more personalized approaches to treating obesity."
The findings were published on Tuesday, Nov. 13, in the journal Obesity.
Four groups of patients
This was the first study examine psychological variables, such as eating patterns, weight history and a range of biological variables, including hormone levels, to identify different types of obesity, Field said.
The team used an advanced computational model, called latent class analysis, to identify different groups of patients among more than 2,400 adults who underwent bariatric surgery between March 2006 and April 2009 -- either gastric bypass or gastric banding. They found four distinct groups.
Group one was characterized by low levels of high-density lipoprotein, the so called "good" cholesterol, and very high levels of glucose in their blood prior to surgery. In fact, 98 percent of this group's members were diabetic, in contrast with the other groups, where about 30 percent were diabetic, the study found.
Group two was characterized by disordered eating behaviors. Specifically, 37 percent had a binge eating disorder, 61 percent reported feeling a loss of control over "grazing" -- regularly eating food between meals -- and 92 percent reported eating when they weren't hungry.
Field found group three surprising, she said. Metabolically, they were fairly average, but they had very low levels of disordered eating -- only 7 percent reported eating when they weren't hungry compared to 37 percent for group one, 92 percent for group two and 29 percent for group four.
"Interestingly, no other factors distinguished this group from the other classes," the authors reported in the paper.
Group four comprised individuals who had been obese since childhood. This group had the highest body mass index (BMI) at age 18 with an average of 32, compared to an average of approximately 25 for the other three groups. A BMI above 30 is considered obese, while 25 is the start of the range defined as overweight. This group also had the highest pre-surgery BMI, an average of 58 compared to approximately 45 for the other three groups, the study reported.
Overall, in the three years following the bariatric procedure, men lost an average of 25 percent of pre-surgery weight and women lost an average of 30 percent. Field and colleagues found that patients in groups two and three benefited more from bariatric surgery than patients in groups one and four. Men and women with disordered eating lost the most, at an average of 28.5 percent and 33.3 percent, respectively, of pre-surgery weight.
Targeted treatments
Identifying these different groups of patients and understanding their characteristics should help obesity research and treatment, Field said. At the extreme end of treatment -- procedures such as bariatric surgery -- it's important to identify who would benefit most from surgery and those for whom the benefits likely won't outweigh the surgical risks, she said.
"One of the reasons why we haven't had stronger findings in the field of obesity research is that we're classifying all of these people as the same," Field said. "It may very well be that there are some incredibly effective strategies out there for preventing or treating obesity, but when you mix patients of different groups together, it dilutes the effect."
Field added that obesity researchers need to test a variety of interventions in a more targeted, personalized manner. For example, mindfulness might be quite effective for people who are overstimulated by the sights and smells of food but might not be effective for people in group three who don't eat when they're not hungry, she said.
In the future, Field hopes to use the same statistical analysis methods on a more general population of overweight individuals to see if the same, or similar, subgroups exist among people at weights less than those defined as obese.
She and her colleagues are now developing a mobile app to measure what influences individuals' eating behaviors in real time. Field hopes the app can eventually be used to provide tailored interventions. She has a beta version of the app, and hopes to move forward in fully developing and testing it.
https://www.sciencedaily.com/releases/2018/11/181113080923.htm
Answer to young people's persistent sleep problems
September 28, 2017
Science Daily/James Cook University
A collaborative research project indicates high rates of sleep problems continuing through teenage years and into early adulthood -- but also suggests a natural remedy.
Dr. Yaqoot Fatima from JCU's Mount Isa Centre for Rural and Remote Health was associated with a study that tracked more than 3600 people from the age of 14 until they were 21.
"Just over a quarter of the 14-year-olds reported sleep problems, with more than 40 percent of those still having sleep problems at 21," said Dr. Fatima.
She said the causes of sleep problems were different at different ages.
"Maternal factors, such as drug abuse, smoking, depression and anxiety among mothers are the most significant predictors of adolescent sleep problems in their children, at 14-years-old. For all people studied, being female, having experienced early puberty, and being a smoker were the most significant predictors of sleep problems at 21 years."
She said adolescent depression or anxiety were linking factors for sleep problems between the two ages.
"It's a vicious circle. Depression and anxiety are well-established risk factors for sleep problems and people with sleep problems are often anxious or depressed," she said.
Dr. Fatima said that as well as the traditional factors, excessive use of electronic media is emerging as another significant risk.
"In children and adolescents, it's found to be strongly associated with later bedtime and shorter sleep duration, increasing the risk of developing sleep disturbances," she said.
Dr. Fatima said the study was worrying as it revealed a high incidence of persistent sleep problems and possible concurrent health problems among young people -- but it also strongly suggested an answer to the problem.
"Even allowing for Body Mass Index and other lifestyle factors, we found that an active lifestyle can decrease future incidence and progression of sleep problems in young subjects. So, early exercise intervention with adolescents might provide a good opportunity to prevent their sleep problems persisting into later life."
She said the next study being considered would look at what factors lead to young adults' sleep problems continuing as they grow older and how that might be prevented.
https://www.sciencedaily.com/releases/2017/09/170928094158.htm
Early to bed and early to rise: it's keeping kids leaner
September 30, 2011
Science Daily/American Academy of Sleep Medicine
Researchers recording the bedtimes and wake times of 2,200 Australian youths found that the night owls were 1.5 times more likely to become obese than the early birds, twice as likely to be physically inactive and 2.9 times more likely to sit in front of the TV and computer or play video games for more hours than guidelines recommend.
A study in the Oct. 1 issue of the journal Sleep recorded the bedtimes and wake times of 2,200 Australian participants, ages 9 to 16, and compared their weights and uses of free time over four days. Children who went to bed late and got up late were 1.5 times more likely to become obese than those who went to bed early and got up early. Furthermore, late-nighters were almost twice as likely to be physically inactive and 2.9 times more likely to sit in front of the TV and computer or play video games for more hours than guidelines recommend.
"The children who went to bed late and woke up late, and the children who went to bed early and woke up early got virtually the same amount of sleep in total," said co-author Carol Maher, PhD, a postdoctoral fellow with the University of South Australia. "Scientists have realized in recent years that children who get less sleep tend to do worse on a variety of health outcomes, including the risk of being overweight and obese. Our study suggests that the timing of sleep is even more important."
Maher said mornings are more conducive to physical activity for young people than nights, which offer prime-time TV programming and social networking opportunities. This relationship between time of day and available activities might explain why more sedentary and screen-based behaviors were observed with later bedtimes, she said. At a time when research is showing that teenagers have a natural tendency to stay up late and wake late, the results of this study could stand as a warning.
"It is widely accepted that the sleep patterns of adolescents are fundamentally different from children and adults, and that it is normal for adolescents to stay up very late and sleep in late in the morning," Maher said. "Our findings show that this sleeping pattern is associated with unfavorable activity patterns and health outcomes, and that the adolescents who don't follow this sleep pattern do better."
Other findings from the University of South Australia study:
- · Early-bed/early-risers went to bed 70 to 90 minutes earlier, woke up 60 to 80 minutes earlier and accumulated 27 minutes more moderate to vigorous physical activity each day than late-risers.
- · Late-bed/late-risers watched TV, played video games or were online 48 minutes longer each day than early-bed/early risers, primarily between 7 p.m. and midnight.
- · Only 12 percent of late-bed/late-risers had an average of two hours or less screen time per day, which is recommended for children and teens by the Australian Department of Health and Aging. In comparison, 28 percent of early-bed/early risers met the recommendation for screen time.
- · On a broad scale, late-bed/late-risers replaced about 30 minutes of moderate to vigorous physical activity with 30 minutes of sedentary behavior each day, relative to the early-bed/early-rise group.
- · Body-mass index (BMI) scores were higher in late-risers than early-risers, and late-risers were more likely to be overweight or obese.
- · Late-bed/late-risers tended to have few siblings, live in major cities, come from lower household incomes and have a part-time job.
http://www.sciencedaily.com/releases/2011/09/110930052216.htm
This is how belly fat could increase your cancer risk
August 24, 2017
Science Daily/Michigan State University
A new study now offers new details showing that a certain protein released from fat in the body can cause a non-cancerous cell to turn into a cancerous one. The research also found that a lower layer of abdominal fat, when compared to fat just under the skin, is the more likely culprit, releasing even more of this protein and encouraging tumor growth.
It's been well established that obesity is a contributor to cancer risk, but how it actually causes cancer is still a question that hasn't been fully explained.
A new Michigan State University study now offers new details showing that a certain protein released from fat in the body can cause a non-cancerous cell to turn into a cancerous one. The federally funded research also found that a lower layer of abdominal fat, when compared to fat just under the skin, is the more likely culprit, releasing even more of this protein and encouraging tumor growth.
"While there have been several advances in treating cancer and improving the quality of life of patients, the number of new cases continues to surge," said Jamie Bernard, lead author and an assistant professor in pharmacology and toxicology.
"It's important to understand the cause so we can do a better job at reducing the number of cancer cases using dietary modifications or therapeutic interventions."
It's estimated that more than one-third of the population is obese. Obesity has been linked to several types of cancers including breast, colon, prostate, uterine and kidney, but Bernard indicated that just being overweight isn't necessarily the best way to determine risk.
"Our study suggests that body mass index, or BMI, may not be the best indicator," Bernard said. "It's abdominal obesity, and even more specifically, levels of a protein called fibroblast growth factor-2 that may be a better indicator of the risk of cells becoming cancerous."
There are two layers of belly fat. The top layer, known as subcutaneous fat, lies right under the skin. The layer under that, called visceral fat, is the one she found to be more harmful.
Bernard and her co-author Debrup Chakraborty, a postdoctoral student in her lab, studied mice that were fed a high-fat diet and discovered that this higher-risk layer of fat produced larger amounts of the fibroblast growth factor-2, or FGF2, protein when compared to the subcutaneous fat. They found that FGF2 stimulated certain cells that were already vulnerable to the protein and caused them to grow into tumors.
She also collected visceral fat tissue from women undergoing hysterectomies and found that when the fat secretions had more of the FGF2 protein, more of the cells formed cancerous tumors when transferred into mice.
"This would indicate that fat from both mice and humans can make a non-tumorigenic cell malignantly transform into a tumorigenic cell," Bernard said.
She added that there are several other factors released from fat, including the hormone estrogen, that could influence cancer risk, but many of those studies have only been able to show an association and not a direct cause of cancer. She also said genetics plays a role.
"There's always an element of chance in whether a person will get cancer or not," Bernard said. "But by making smarter choices when it comes to diet and exercise and avoiding harmful habits like smoking, people can always help skew the odds in their favor."
Bernard indicated that she is already looking at identifying new anti-cancer compounds in her research that could stop the effects of FGF2.
https://www.sciencedaily.com/releases/2017/08/170824101756.htm
Women who gain too much or too little weight during pregnancy at risk for having an overweight child
April 14, 2014
Science Daily/Kaiser Permanente
Gaining both too much or too little weight during pregnancy appears to increase the risk of having an overweight or obese child, according to a study. In one of the largest studies to examine current Institute of Medicine recommendations regarding pregnancy weight gain in relation to childhood obesity, researchers reviewed the electronic health records of 4,145 racially diverse females who had completed a health survey between 2007 and 2009 and subsequently had a baby.
In one of the largest studies to examine current Institute of Medicine recommendations regarding pregnancy weight gain in relation to childhood obesity, researchers reviewed the electronic health records of 4,145 racially diverse female members of Kaiser Permanente in Northern California who had completed a health survey between 2007 and 2009 and subsequently had a baby.
Researchers reviewed the medical records of those children between ages 2 and 5 years old and found that:
· Among all women who gained more than the recommended weight during pregnancy, 20.4 percent of their children were overweight or obese, compared with 19.5 percent in women who gained less than recommended weight and 14.5 percent in women who gained weight within the guidelines.
· Women with a normal Body Mass Index measurement before pregnancy who gained less than the recommended amount were 63 percent more likely to have a child who became overweight or obese.
· Women with a normal BMI before pregnancy with weight gain above recommendations were 80 percent more likely to have an overweight or obese child.
"The stronger association we found among normal weight women who gained too much or too little weight during pregnancy suggests that perhaps weight gain in pregnancy may have an impact on the child that is independent of genetic factors," said senior investigator Monique M. Hedderson, PhD, Kaiser Permanente Division of Research in Oakland, Calif.
"Gaining either too little or too much weight in pregnancy may permanently affect mechanisms that manage energy balance and metabolism in the offspring, such as appetite control and energy expenditure," said the study's lead author Sneha Sridhar, MPH, Kaiser Permanente Division of Research. "This could potentially have long-term effects on the child's subsequent growth and weight."
http://www.sciencedaily.com/releases/2014/04/140414092115.htm
Light exposure and kids' weight: Is there a link?
World-first study revealing light exposure plays a role in the weight of preschool children
January 7, 2016
Science Daily/Queensland University of Technology
Light exposure plays a role in the weight of preschool children, a world-first study reveals. The researchers studied children aged three to five, from six childcare centers, measuring the children's sleep, activity and light exposure for a two week period, along with height and weight to calculate their BMI, then followed up 12-months later.
https://images.sciencedaily.com/2016/01/160107104820_1_540x360.jpg
Around 42 million children around the globe under the age of five are classified as overweight or obese so this study is a significant breakthrough and a world-first, say the researchers.
Credit: © TuTheLens / Fotolia
PhD student Cassandra Pattinson and colleagues Simon Smith, Alicia Allan, Sally Staton and Karen Thorpe studied children aged three to five, from six Brisbane childcare centres. At time 1, they measured children's sleep, activity and light exposure for a two week period, along with height and weight to calculate their BMI, then followed up 12-months later
"At time 1, we found moderate intensity light exposure earlier in the day was associated with increased body mass index (BMI) while children who received their biggest dose of light -- outdoors and indoors -- in the afternoon were slimmer," said Ms Pattinson of the Environmental Light Exposure is Associated with Increased Body Mass in Children study.
"At follow-up, children who had more total light exposure at Time 1 had higher body mass 12 months later. Light had a significant impact on weight even after we accounted for Time 1 body weight, sleep, and activity.
"Around 42 million children around the globe under the age of five are classified as overweight or obese so this is a significant breakthrough and a world-first.
"Artificial lighting, including light given off by tablets, mobile phones, night lights, and television, means modern children are exposed to more environmental light than any previous generation. This increase in light exposure has paralleled global increases in obesity."
The research team is from QUT's Institute of Health and Biomedical Innovation and the Centre for Children's Health Research
Ms Pattinson said it is known the timing, intensity and duration of exposure to both artificial and natural light have acute biological effects in mammals.
"The circadian clock -- also known as the internal body clock -- is largely driven by our exposure to light and the timing of when that happens. It impacts on sleep patterns, weight gain or loss, hormonal changes and our mood," Ms Pattinson said
"Factors that impact on obesity include calorie intake, decreased physical activity, short sleep duration, and variable sleep timing. Now light can be added to the mix."
Ms Pattinson said the next step was to figure out how the research can be used in the fight against obesity in children.
"We plan to conduct further studies with pre-schoolers and also infants," she said.
"Animal studies have shown that timing and intensity of light exposure is critical for metabolic functioning and weight status. Our findings suggest that the same applies to us.
"This research suggests that exposure to different types of light (both artificial and natural) at different times now needs to be part of the conversation about the weight of children."
http://www.sciencedaily.com/releases/2016/01/160107104820.htm