Posts tagged body weight
Articles and news from the latest research reports.
Fish oil may stall effects of junk food on brain
Data from more than 180 research papers suggests fish oils could minimise the effects that junk food can have on the brain, a review by researchers at the University of Liverpool has shown.
The team at the University’s Institute of Ageing and Chronic Disease reviewed research from around the world to see whether there was sufficient data available to suggest that omega-3s had a role to play in aiding weight loss.
Stimulating the brain
Research over the past 10 years has indicated that high-fat diets could disrupt neurogenesis, a process that generates new nerve cells, but diets rich in omega-3s could prevent these negative effects by stimulating the area of the brain that control feeding, learning and memory.
Data from 185 research papers revealed, however, that fish oils do not have a direct impact on this process in these areas of the brain, but are likely to play a significant role in stalling refined sugars and saturated fats’ ability to inhibit the brain’s control on the body’s intake of food.
Dr Lucy Pickavance, from the University’s Institute of Ageing and Chronic Disease, explains: “Body weight is influenced by many factors, and some of the most important of these are the nutrients we consume. Excessive intake of certain macronutrients, the refined sugars and saturated fats found in junk food, can lead to weight gain, disrupt metabolism and even affect mental processing.
“These changes can be seen in the brain’s structure, including its ability to generate new nerve cells, potentially linking obesity to neurodegenerative diseases. Research, however, has suggested that omega-3 fish oils can reverse or even prevent these effects. We wanted to investigate the literature on this topic to determine whether there is evidence to suggest that omega-3s might aid weight loss by stimulating particular brain processes.”
Research papers showed that on high-fat diets hormones that are secreted from body tissues into the circulation after eating, and which normally protect neurons and stimulate their growth, are prevented from passing into the brain by increased circulation of inflammatory molecules and a type of fat called triglycerides.
Molecules that stimulate nerve growth are also reduced, but it appears, in studies with animal models, that omega-3s restore normal function by interfering with the production of these inflammatory molecules, suppressing triglycerides, and returning these nerve growth factors to normal.
Positive step
Dr Pickavance added: “Fish oils don’t appear to have a direct impact on weight loss, but they may take the brakes off the detrimental effects of some of the processes triggered in the brain by high-fat diets. They seem to mimic the effects of calorie restrictive diets and including more oily fish or fish oil supplements in our diets could certainly be a positive step forward for those wanting to improve their general health.”
The research is published in the British Journal of Nutrition. Dr Pickavance will also be discussing the effects of high-fat diets on meal patterns and the impacts of high-saturated fats on muscle composition at the 20th European Congress on Obesity at the Liverpool Arena and Convention Centre later this month.
Small genetic change has heavy consequences
One small change to the DNA sequence can cause more weighty changes to the human body, according to a new study released today. The discovery comes thanks to a worldwide consortium of researchers that includes Professor and Chair of Quantitative Genetics at The University of Queensland (UQ), Peter Visscher, from the Queensland Brain Institute (QBI) and Diamantina Institute (DI) at UQ.
He and his team have found a single change in genetic sequence at the gene FTO had a significant effect on the variability of body mass index (BMI). BMI is a commonly used measure of obesity. It measures someone’s weight adjusted for his or her height.
Professor Visscher said that the genetic change, called a single nucleotide polymorphism (SNP), was the replacement of one nucleotide – the units that make up our DNA – with another. “They are the most abundant type of variation in the human genome,” he said. “SNPs occur normally throughout our DNA and most have no effect on our health, however, we’ve found one that does have a small but significant effect on variation in BMI.”
After analysing data from almost 170,000 people, he and his team established that those with a sequence variant in the FTO gene not only weighed more on average, but the measured weights varied more than in the group without the variant. The variability of BMI within the group with two copies of the variant was, in fact, 7 per cent larger than the group without the variant.
Professor Visscher said this equated to around half a kilogram difference in the standard deviation of weight. “So as a group, people with two copies of the weight increasing variant are a few kilograms heavier and vary more,” he said. Genetic differences in variability of specific traits have been seen in many plant and animal species but specific genes or mechanisms to explain the phenomenon had not been identified.
Professor Visscher’s study is the first to look systematically at genetic effects on variation of a complex trait in humans using a very large sample size. “The study is important because it demonstrates that genes can be found that affect trait variability. “This is a first step towards understanding how genes control variation,” Professor Visscher said.
This study is also the first to offer researchers an indirect method to measure genotype by environment interactions without having a measure of specific environmental factors. “If a gene interacts with specific environmental factors then this can be observed with our method,” Professor Visscher said.
“For example, if the effect of a gene on weight is smaller in people who physically exercise than in people who do not, then this will lead to less variation among people with two copies of the weight decreasing variant.
“In our study we did not measure specific environmental effects such as physical exercise so we can’t say for sure whether our results are due to a genotype-environment interaction.”
This is the second study Professor Visscher has published in the prestigious journal Nature this year. Earlier this year he identified that genetic differences also affect how intelligence changes across a lifetime. The work also suggested these changes in intelligence were largely influenced by environmental factors.
(Source: uq.edu.au)