Latest News & Research: 11 February 2020
This week: Exercise boosts brain as much as cup of coffee • How high protein diets may increase heart attack risk • Weekend ‘eating jet lag’ linked to higher BMI • Les Mills Quarterly to hit Brisbane in March
Weekend ‘eating jet lag’ linked to higher BMI
Recent study findings have added to the evidence that maintaining a regular eating schedule is key for preventing obesity.
Researchers from the University of Barcelona found that a more improvised weekend eating schedule may link to an increase in body mass index (BMI).
The study’s authors refer to people’s weekend diversions from their regular eating schedule as ‘eating jet lag’, which they suggest may be as physiologically disruptive as the body confusion that can occur when traversing time zones.
The cross-sectional study is part of the doctoral thesis of first author María Fernanda Zerón Rugerio of the University of Barcelona (UB) in Spain. The paper, which other UB researchers co-authored, appears in the journal Nutrients.
The authors analysed data from 1,106 undergraduate and postgraduate students between the ages of 18 and 25 years who reported their weekend eating schedules during the school year. The study ran from 2017 to 2019. Each participant also self-reported their height and weight – the two measurements that make up BMI. The study’s authors believe that this is the first study to focus on the effect on obesity of changes in meal timing between weekdays and weekends.
From the students’ responses, researchers were able to determine the cohort’s average meal duration during the week and on the weekends, as well as the eating midpoint – halfway between the first and last meal of the day – for both weekdays and weekends.
To calculate an individual’s overall eating jet lag value, they used a simple formula: eating midpoint on weekends minus eating midpoint on weekdays. From there, the researchers accounted for other influences that could affect BMI, including diet quality, sleep duration, gender, and chronotype.
The authors found that those with an overall eating jet lag of 3.5 hours or more had higher BMI values. They used the same formula to calculate the separate eating jet lags for breakfast, lunch, and dinner.
Not surprisingly, given the opportunity to sleep in at the weekend, the meal that exhibited the greatest amount of jet lag was breakfast. The study showed that 64% of participants experienced more than an hour of breakfast-eating jet lag each weekend, with this duration exceeding 2 hours for 22% of these individuals.
The researchers did not detect any correlation between the eating jet lag for a particular meal and a higher BMI.
Eating jet lag may stem from the same sort of conflict between a body’s circadian rhythm and unusual activity as regular travel jet lag and ‘social jet lag’, which results from unusual weekend sleeping schedules.
The study noted, ‘The circadian system is comprised of a master clock and a network of peripheral clocks, all of which are organised in a hierarchical manner.’
One of the study authors, Trinitat Cambras of UB’s Department of Biochemistry and Physiology, elaborated, saying: ‘Our biological clock is like a machine and is ready to unchain the same physiological and metabolic response at the same time of the day, every day of the week. Fixed eating and sleep schedules help the body to be organised and promote energy homeostasis.’
Lead author Maria Izquierdo Pulido of UB’s Institute for Nutrition and Food Safety tied the biological clock to the way in which the body processes food: ‘As a result, when intake takes place regularly, the circadian clock ensures that the body’s metabolic pathways act to assimilate nutrients. However, when food is taken at an unusual hour, nutrients can act on the molecular machinery of peripheral clocks (outside the brain), altering the schedule and thus, modifying the body’s metabolic functions.’
There is still a need for more research regarding the link between eating jet lag and BMI. Izquierdo Pulido pointed out, however, that it is already known that maintaining a regular schedule has benefits. Scientists may now add combatting eating jet lag to these.
‘Apart from diet and physical exercise, which are two pillars regarding obesity, another factor to be considered is regular eating schedules, since we proved it has an impact on our body weight.’
Source: Medical News Today
High protein diets may increase heart attack risk
A recent study in mice has suggested that high protein diets may put cardiovascular health at risk.
‘There are clear weight loss benefits to high protein diets, which has boosted their popularity in recent years’ said Dr Babak Razani, an associate professor of medicine from Washington University School of Medicine in St. Louis, MO; ‘But, animal studies and some large epidemiological studies in people have linked high dietary protein to cardiovascular problems.’
Razani and his colleagues set out to establish whether high protein diets might actually influence cardiovascular health directly by facilitating the buildup of plaque inside the arteries.
The researchers conducted their study in mouse models and have now published their findings in the journal Nature Metabolism.
For the study, Razani and his team fed mice a high fat diet in order to make the mice develop arterial plaque. But while some of the mice received a diet that was high in fat and proteins, others received a high fat diet with a low protein content. This allowed the investigators to pinpoint any differences.
‘A couple of scoops of protein powder in a milkshake or a smoothie adds something like 40 grams of protein – almost equivalent to the daily recommended intake’ noteds Razani; ‘To see if protein has an effect on cardiovascular health, [in our study] we tripled the amount of protein that the mice receive in the high fat, high protein diet – keeping the fat constant. Protein went from 15% to 46% of calories for these mice’ he explained.
Razani and his team soon found that the rodents that had fed on the high fat, high protein diet had not just developed atherosclerosis – a condition characterised by the buildup of arterial plaque – but that this was significantly worse than in the mice that had eaten the high fat, low protein diet.
While the mice in the high fat, high protein diet did not gain any weight despite ingesting lots of fats, they developed approximately 30% more plaque in the arteries compared with the mice on the high fat but low protein diet.
Moreover, the kind of plaque that built up in these mice’s arteries tended to be what researchers call ‘unstable’ plaque — plaque that is thinner, and may break off the arterial wall easily, increasing the risk of blockages and, potentially, a heart attack.
‘This study is not the first to show a telltale increase in plaque with high protein diets, but it offers a deeper understanding of the impact of high protein with the detailed analysis of the plaques’ Razani said; ‘In other words, our study shows how and why dietary protein leads to the development of unstable plaques’.
Mammal bodies, the researchers explained, actually have a first-line defence against arterial plaque. A type of white blood cells called ‘macrophages’ usually ‘pick up’ on the presence of these deposits and remove them.
However, sometimes they are unequal to the task. When this happens, macrophages die, leaving arterial plaque to continue to build up.
‘In mice on the high protein diet, their plaques were a macrophage graveyard’ Razani said; ‘Many dead cells in the core of the plaque make it extremely unstable and prone to rupture. As blood flows past the plaque, that force – especially in the context of high blood pressure – puts a lot of stress on it. This situation is a recipe for a heart attack.’
The researchers also looked into the mechanism through which dietary protein may contribute to the creation of unstable arterial plaque. To do so, they looked at what happens following the digestion of dietary protein once it breaks down into the amino acids that formed it.
The team found that the excess amino acids derived from a diet with a high protein content actually activate another protein – called mTOR – that is present in macrophages.
When mTOR becomes active, it sends a signal to the macrophage to focus on growing rather than identifying and cleaning up plaque buildup. Eventually, the abnormal growth process leads to macrophage death.
Two specific amino acids, leucine and arginine, were the main players when it came to incapacitating macrophages, explained Razani and his colleagues. But knowing this may also help us understand which foods people should avoid: for instance, ‘[l]eucine is particularly high in red meat, compared with, say, fish, or plant sources of protein’ noted the researcher.
And the understanding that some amino acids derived from dietary protein might be more harmful than others could also inform further research around diet and cardiovascular health. ‘A future study might look at high protein diets with different amino acid contents to see if that could have an effect on plaque complexity’ said Razani; ‘Cell death is the key feature of plaque instability. If you could stop these cells from dying, you might not make the plaque smaller, but you would reduce its instability’ he noted.
Source: Medical News Today
Exercise boosts brain as much as cup of coffee
Just 20 minutes of exercise is as good as a coffee for our working memory, according to a new study.
In a new study, which appears in Nature Scientific Reports, researchers compared the effects of caffeine and exercise on working memory and concluded that acute exercise can be as good for the mind as it is for the body.
While getting a regular caffeine fix can have a positive effect on health – with studies linking caffeine with everything from long-term memory to fighting off disease – the fact is that caffeine is a psychoactive substance and that some side effects come with it.
These side effects inspired a new study led by Harry Prapavessis, the director of the Exercise and Health Psychology Laboratory at Western University in Ontario, Canada.
Together with former graduate student Matthew Fagan and graduate student Anisa Morava, Prapavessis compared the effects of exercise and caffeine.
Despite the positives we know about caffeine, the negatives can often outweigh the benefits.
Anxiety-like symptoms, body tremors, and withdrawal, all have an association with the regular consumption of caffeine.
Caffeine withdrawal can be an unwelcome surprise for anyone trying to cut down. Nausea, fatigue, low energy, irritability, low mood, and a ‘foggy brain’ are all common symptoms. A review of studies investigating caffeine withdrawal found that 50% of people experienced a headache that lasted up to 9 days after they stopped consuming caffeine.
Caffeine withdrawal can affect cognitive function, which may be a concern for anyone using caffeine to keep their brain ticking.
Recent research has suggested that just a single bout of exercise improves mood and cognition.
Countless other studies suggest that physical exercise can bring health benefits, such as fighting disease and extending life. Yet, we often reach for a coffee instead of heading out of the door and getting moving. The aim of this new study was to compare exercise and caffeine in terms of how effective they are in improving working memory.
Working memory is key to our ability to function as a curious human being. It helps the learning process and makes it possible to store information, such as phone numbers or a shopping list, in the short term.
To test this functional part of our cognition, the team used an n-back test, which resembles the card game pairs or snap. In such games, the aim is to spot the repetition of items that appear in succession. In the study at Western, the researchers presented the participants with a list of items. As with the popular card game, they had to spot any repeats of an item.
Prapavessis and his team tested whether the participants could spot repeated items up to three times back in the list. The more items to which the participants had to return, the clearer it was how much information their working memory could store and keep ready for recall.
To compare the effects of caffeine and exercise on working memory, the team randomly assigned each participant to one of two groups. In the first part of the study, both caffeine consumers and noncaffeine consumers underwent the n-back tasks prior to and after acute exercise and caffeine administration.
The second part of the study focused on caffeine withdrawal. Here, the caffeine drinkers took the same n-back tests after 12 hours of caffeine deprivation. The results of the study showed that both exercise and caffeine had a similar effect. The improvements in the participants’ working memory were similar after spending 20 minutes on a treadmill and consuming a single serving of caffeine.
This might seem like good news for people who enjoy a regular triple espresso. However, the main takeaway of this study is that exercise, with all its long-term benefits, can help improve mood and focus just as much as caffeine can – and without the potential for the negative side effects of caffeine and caffeine withdrawal symptoms.
The study also bears some good news for coffee drinkers, finding that exercise can help with caffeine withdrawal symptoms, too, should a person decide to cut down.
‘If people experience withdrawal, an acute, brisk walk may reduce some of the symptoms’ said study co-author Anisa Morava.
Source: Medical News Today
Les Mills Quarterly Workshop to hit Brisbane in MarchOn Sunday 1 March, 700 Les Mills instructors and enthusiasts will convene at the Royal International Convention Centre in Brisbane, to participate in the Les Mills Q1 Super Workshop.
‘It’s been a while since we held a Super Workshop in Brisbane’ says Ryan Hogan, CEO of Les Mills Asia Pacific (LMAP), ‘so we’re really excited, and expecting a great response.’
The Super Workshops typically feature a huge venue, rock concert-like sound and production, iconic Les Mills program creators and presenters, and hundreds of members of the Les Mills instructor tribe trying out the latest releases in mass-participation group fitness classes.
‘With a stellar line-up like this, our instructors and participants are in for a real treat. It’s not every day that our Aussie Tribe have the opportunity to learn first-hand from some of the world’s most accomplished Les Mills trainers and presenters, so we are expecting this event to sell out’ Hogan said.
Les Mills instructors are also being encouraged to invite their most passionate and enthusiastic class members to attend this Super Workshop – a move that has generated significant online chatter among instructors.
‘The reason we’ve opened this Super Workshop up to class participants is because, ultimately, those people – the ones who are always in the front row of every class, or who are rarely absent – are the individuals who will subsequently proceed to promote the Les Mills programs on their club’s timetable, and specifically, their instructor’s classes to everyone they know! And of course, if they’re really passionate about Les Mills programs then they could also be identified as ideal candidates as future instructors. So this Workshop can serve as an opportunity to for them to catch a glimpse into the world of teaching and instructing group fitness.’
Les Mills instructors can buy their tickets at a discounted rate via their instructor portal on the LMAP website at www.lesmills.com.au/quarterly-workshop
Source: Les Mills Asia Pacific