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metabolic

Octopuses May Be Adapting to The Rising Acidity of Our Oceans, Study Suggests

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We know that all the excess CO2 we’re pumping into the air – alongside a host of other damaging effects – is driving up the acidity of the oceans as it sinks and dissolves into the water, but it seems as though the hardy octopus can find ways to adapt to its rapidly changing environment.

 

Previous research into the impact of ocean acidification on cephalopods such as octopuses, cuttlefish, and squid has shown some indication increased carbon dioxide in the water could negatively impact this type of marine life.

However, in a new study, a group of Octopus rubescens – a species of octopus common to the west coast of North America – were observed adjusting their routine metabolic rate (RMR) over a series of weeks in response to lowering pH levels in the surrounding water.

“Challenges to an organism’s physiology are often reflected in changes in energy use and therefore can be observed as changes in aerobic metabolic rate,” write the researchers in their paper.

A total of 10 octopuses were studied under controlled lab conditions, with RMR measured immediately after exposure to acidic water, after one week, and after five weeks. Critical oxygen pressure – a measure of whether not not animals are getting enough oxygen – was monitored at the same time.

To begin with, high levels of metabolic change were detected in the creatures – a sort of shock reaction that actually conflicts with earlier research into cephalopods, which had recorded a reduction in metabolic change in similar scenarios.

 

However, RMR had returned to normal after one week, and remained the same five weeks later, suggesting some adaptation had occurred. The increased acidity did have an impact on the ability of the octopuses to function at low oxygen levels, however.

“This response in RMR suggests that O. rubescens is able to acclimate to elevated CO2 over time,” write the researchers. “The observed increase in RMR may be the result of multiple acute responses to hypercapnia [increased CO2 in the blood], possibly including both behavioural and physiological strategies.”

Those strategies could include preparing to move to find a new stretch of water to inhabit, for example, the researchers suggest (something that wasn’t possible here). The short RMR boost might also reflect the octopuses making quick adjustments to their biological processes to suit the new acid level.

The study is the first to look at both short-term (one week) and longer-term (five week) changes in metabolism rates in cephalopods in response to ocean acidification. We know these creatures are tough, and it seems they even have coping strategies that might allow them to adapt to humans destroying the natural environment all around them.

None of this means that we should be okay with the current climate crisis though, or not be trying to make major changes to reverse it. When we don’t take proper care of the planet, it’s not just ourselves that we’re potentially dooming to extinction.

Also, these tests were done in controlled laboratory conditions that don’t take into account many other interlinking factors in the animals’ natural environment. For instance, even if the octopus themselves are able to adjust, what about their food supply?

“While this species may be able to acclimate to near-term ocean acidification, compounding environmental effects of acidification and hypoxia may present a physiological challenge for this species,” write the researchers.

The research has been published in Physiological and Biochemical Zoology.

 



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Just 12 Minutes of Intense Exercise Is Enough to Change Biomarkers in Your Blood

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Short bursts of exercise have more of an impact on our bodies than you might think: a new study shows that just 12 minutes of intense activity is enough to significantly change the biomarkers of metabolic health in people’s blood.

 

Researchers analysed the reactions of 411 middle-aged men and women to 12 minutes of “vigorous” exercise, finding that the exercise had an effect on more than 80 percent of circulating metabolites in the participants’ blood.

These metabolites can act as indicators of cardiometabolic, cardiovascular, and long-term health, suggesting that even a short hit of activity is enough to benefit some of the body’s key biological processes.

“Much is known about the effects of exercise on cardiac, vascular and inflammatory systems of the body, but our study provides a comprehensive look at the metabolic impact of exercise by linking specific metabolic pathways to exercise response variables and long-term health outcomes,” says Gregory Lewis, a specialist in heart failure and cardiac transplantation at Massachusetts General Hospital (MGH).

“What was striking to us was the effects a brief bout of exercise can have on the circulating levels of metabolites that govern such key bodily functions as insulin resistance, oxidative stress, vascular reactivity, inflammation and longevity.”

One example mentioned by the researchers is the metabolite glutamate. It’s linked to heart disease, diabetes, and a shorter lifespan, and it fell by 29 percent on average.

 

Meanwhile the metabolite DMGV (dimethylguanidino valeric acid), which is associated with an increased risk of diabetes and liver disease, dropped by 18 percent.

The researchers reported some variations across the sex and body mass index of the participants: there were signs that obesity can limit some of the benefits of high intensity exercise, for example.

A total of 588 metabolites were tracked and measured by the researchers. Further down the line the same techniques used here could be used to get a more general picture of someone’s health from the metabolites circulating in their blood.

“Intriguingly, our study found that different metabolites tracked with different physiologic responses to exercise, and might therefore provide unique signatures in the bloodstream that reveal if a person is physically fit, much the way current blood tests determine how well the kidney and liver are functioning,” says cardiologist Matthew Nayor, from MGH.

Data for the new analysis was pulled from the Framingham Heart Study, a long-running research project that now covers three generations of people. As records for the study go back to 1948, researchers can see how metabolic signatures affect long-term health.

There’s now a growing collection of studies showing that even a little bit of exercise can go a long way: even if you only get moving for an hour a week, the body can feel the benefit.

Getting moving and staying active can help to fight cancer, boost your memory, and help you lose weight. Thanks to this study and others like it, we’re starting to understand more about how exercise helps the body on the smallest scales.

“We’re starting to better understand the molecular underpinnings of how exercise affects the body and use that knowledge to understand the metabolic architecture around exercise response patterns,” says cardiologist Ravi Shah, from MGH.

“This approach has the potential to target people who have high blood pressure or many other metabolic risk factors in response to exercise, and set them on a healthier trajectory early in their lives.”

The research has been published in Circulation.

 



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What Is ‘Reverse Dieting’ Anyway? What We Do And Don’t Know About This Post-Diet Plan

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While there are many debates about which type of diet is best for weight loss and health, it’s often not the weight loss which is the biggest challenge, but rather avoiding weight regain afterwards.

 

This can lead to cycles of dieting and weight gain, or “yo-yo” dieting, which can cause people to have a less healthy relationship with food, worse mental health and a higher body weight.

But recently, “reverse dieting” has gained popularity online as a post-diet eating plan that claims it can help you avoid weight regain by eating more. In simple terms, it’s a controlled and gradual way of increasing from a low calorie weight-loss eating plan back to your more “normal” pre-diet way of eating.

The idea with reverse dieting is that gradually increasing calorie intake following a deficit will allow your body and your metabolism to “adjust” so that you can avoid weight regain while eating more.

However, there is currently no scientific evidence showing that reverse dieting works as advocates claim.

Metabolic rate

Reverse dieting is based around the theory that our body has baseline “set points” for metabolism and calorie intake hardwired into our biology, and if we go above these points we gain weight.

The idea is that reverse dieting can shift these “set points” upwards if a person slowly increases the amount of calories eaten as food. This would theoretically “boost” their metabolism, allowing them to consume more food and calories without gaining weight.

 

However, the idea that as humans we have a “set point”, which we can manipulate with dietary changes, is not supported by research.

The main reason for this is because a number of factors influence our weight and metabolism, including how it changes. Among them are how we’re brought up, what food we have access to, what type of exercise we do, and our genetics.

But the most important influence over how our body uses calories – and therefore our weight – is our resting (or basal) metabolic rate. This is the amount of calories our body needs in order to keep itself alive. This accounts for about 60 to 70 percent of the calories we use daily.

Our basal metabolic rate is mostly determined by our age, weight, sex and muscle mass – your diet has little effect on it.

Eating at or below your basal metabolic rate will result in weight loss, and eating above it will result in weight gain.

Our basal metabolic rate also increases as we gain weight or muscle mass, and decreases as we lose weight or muscle mass (the evidence shows that the more muscle your body has, the more calories it needs to function).

 

Exercise also increases how many calories we use, but usually not enough to massively affect our weight. And though a high protein diet can alter metabolic rate somewhat, our body weight and muscle mass have the greatest effect on it.

So reverse dieting only appears to work by controlling calorie intake. There’s currently no evidence that you can alter your metabolism or metabolic rate by introducing more calories slowly and gradually.

Put simply, if you eat more calories than your body requires, you will gain weight. What we do know is that certain habits, like regularly eating breakfast and exercise, help people avoid weight regain after dieting.

Food relationship

While there’s currently little research investigating the effects of reverse dieting on metabolism, it could still help people in other ways.

When some people are losing weight, they may feel in control of how they eat. But for some people, stopping their diet could lead to perceived loss of control.

Reverse dieting might give some people the confidence to return to a more sustainable way of eating, or help them move out of a cycle of restrictive dieting.

 

Advocates of reverse dieting suggest it can also help manage problems of appetite and cravings. This is because additional foods can be added in as the amount of calories and food eaten is increased.

While fewer cravings can help with weight maintenance, this evidence does not come from studies where foods were slowly reintroduced.

For some people, counting calories or restrictive dieting can tend to lead to an unhealthy relationship with their bodies and the food they eat.

Orthorexia nervosa is becoming increasingly common, and is characterised by an obsession with eating healthy – which can lead to an unhealthy restriction of and relationship with foods.

While wanting to eat a healthy diet can seem on the surface to be a good thing, when it becomes orthorexia and enjoyment of food is replaced by an anxiety of feeling the need to account for every calorie, this could lead to poor mental health.

Reverse dieting is one approach, but some would argue other methods, such as intuitive eating – which emphasises listening to your body’s hunger cues and only eating when you’re hungry – might be psychologically healthier. Intuitive eating may help people both regain and trust their appetites, and stop the cycle of restriction and calorie counting.The Conversation

Duane Mellor, Senior Teaching Fellow, Aston Medical School, Aston University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 



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Giant Viruses Carry Genetic Code That May Control The Metabolism of Living Things

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The more we discover about giant viruses, the more questions we seem to have. Unlike most viruses, these giant strains are so large they can even be mistaken for bacteria, and the size and complexity of their genomes seem to present no end of mysteries.

 

Giant viruses were only first identified this century, but numerous such finds since then have challenged our long-held assumptions about what viruses really are, including whether they should in fact be considered living creatures after all.

Some of these giant viruses even seem to create their own genes; others possess genetic code we’ve never encountered anywhere before.

Giant viruses aren’t only notable for what’s different about them, though. Increasingly, we seem to find types with features only seen in living cells, and a striking new discovery made by scientists at Virginia Tech has found other puzzling genetic similarities between giant viruses and cellular life.

“It used to be that there was very little overlap, and the more we learn, the more they continue to overlap,” explains microbial ecologist Frank Aylward.

“In terms of the genomic repertoires, they have much more in common than we would actually expect.”

In a new study, researchers conducted a survey of viral diversity, sifting through publicly available metagenome databases containing a trove of genetic code, from which they assembled putative genomes for 501 different kinds of giant viruses in the proposed order of nucleocytoplasmic large DNA viruses (NCLDVs), mostly from aquatic environments (where they infect things like algae).

 

In addition to finding expected genes for processes such as capsid construction and viral infectivity, the team found giant viruses harbour a huge diversity of genes involved in aspects of cellular metabolism, including processes such as nutrient uptake, light harvesting, and nitrogen metabolism.

Metabolic genes have been identified in viruses before, but this is something different, the researchers say.

Previous research in NCLDVs has uncovered genes thought to be acquired from cellular life through lateral gene transfer – the movement of genetic material between organisms, as opposed to it being passed down from parent to offspring. In the viral context, this suggests viruses might acquire genes by chance from infected hosts.

Here, however, the team found evolutionary lineages of viral metabolic genes that went far deeper, suggesting longstanding relationships between pathogens and hosts, the symbiotic significance of which we can’t yet fully unravel.

“It implies that the viruses have had these genes for millions of years, even billions of years, and they’re virus-specific metabolic genes,” Aylward explains.

“Once viruses infect a cell, we can’t think of the cell as being its own autonomous entity anymore. The fundamental aspects of cellular physiology are being rewired by these viruses upon infection.”

 

In other words, giant viruses and their ancient ancestors may have dwelled alongside cellular organisms for eons, not only replicating inside the cells of living creatures, but exerting an unseen influence on their metabolic processes all this time.

Like many of the other discoveries we seem to make about giant viruses, it seems to call for a double-take, if not an outright paradigm shift.

“Viruses have historically been viewed as accessories to cellular life, and as such their influence on biogeochemical cycles has largely been viewed through the lens of their impact on host mortality, rather than any direct metabolic activities of their own,” the authors write in their paper.

“The large number of cellular metabolic genes encoded in NCLDV genomes that we reveal in this study brings to light an alternative view in which virus-specific enzymes have a direct role in shaping virocell physiology.”

Next, the researchers want to conduct experimental studies exploring how host metabolisms might be affected by giant viruses, and by the viral genes ostensibly carried to rewire metabolic processes.

No matter what answers we find, given it’s giant viruses we’re dealing with, you can bet there will be plenty of new unknowns to puzzle over.

“They’re just a bag of mystery,” says microbiologist Mohammad Moniruzzaman. “They’re like a big forest and you are standing in front of the forest and you don’t know what’s in it.”

The findings are reported in Nature Communication.

 



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Scientists Discover Deep-Sea Bacteria Has a Metabolism Unlike Anything We’ve Seen Before

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A curious kind of bacteria found on the floor of the deep ocean might have a metabolism unlike anything we’ve seen before.

Known as Acetobacterium woodii, scientists in Germany claim that this species, which also lives in the intestines of termites, can both create and use hydrogen and carbon dioxide to produce energy all on its own, even without the need for oxygen. 

 

The ability to survive on organic and inorganic substances alike without oxygen makes this bacterium quite unique among microorganisms, and while scientists have long suspected something like this existed, it’s never been clearly described among acetogenic bacteria, which produce methane free from oxygen. 

“There have already been speculations that many ancient life forms possess the kind of metabolism that we have described in A. woodii,” microbiologist Volker Müller from Goethe University Frankfurt explains.

“This is assumed, for example, for the Asgard archaea that were just discovered a few years ago on the seabed off of California. Our investigations provide the first evidence that these paths of metabolism actually exist.”

Hydrothermal vents were only discovered in the late ’70s, and since then we’ve come to realise these strange habitats are home to complex and dynamic forms of life, including mats of bacteria several centimetres thick, which feed on inorganic compounds like hydrogen and sulphide, as they rush up through the subsurface.

In fact, this might be one of the largest reservoirs of diverse hydrogen-converting microorganisms in the world, and, as a result, it’s thought that some of these creatures may have metabolic systems unlike anything we’ve seen before. 

 

The thing is, excess hydrogen inhibits the fermentation process, and even the weakest hydrothermal vents easily exceed the levels needed to harbour fermentative bacteria. So how is it that such microbes exist down here?

Apparently, the answer lies in sticking together. If one bacteria that produces hydrogen teams up with another microorganism that oxidises hydrogen, like methane-producing archaea, then the latter can maintain good environmental conditions for the former to live and reproduce.

fmicb 09 02873 g001(Adam and Perner, Frontiers in Microbiology, 2018)

It’s a helpful little friendship – or syntrophic relationship – deep under the sea, but while this is probably the dominant kind of fermentation that occurs in these environments, it may not be the only one.

The new analysis essentially claims to have found a microorganism capable of playing both roles in just one bacterial cell.

“In contrast, A. woodii combines the metabolic features of two syntrophic partners in one bacterial cell,” the authors of the analysis conclude.

“Depending on the environmental conditions A. woodii can play the part of the fermenting partner… or the hydrogen consuming partner.”

 

It’s unclear exactly how the bacteria achieve this, but the authors postulate one pathway ferments organic substrates into acetic acid, alcohols, and molecular hydrogen, while another pathway acts as an ‘electron sink’ for the exterior environment, making fermentation energetically possible by forming acetic acid from CO2 and hydrogen.

Turning off the gene that controls the enzyme responsible for hydrogen production, researchers found the bacterium could only grow on a fructose substrate if external hydrogen was added. Further tests revealed that both paths are connected to hydrogen that does not leave the cell.

While this double metabolism may exist in other bacteria, the system is much less common. A. woodii has a lower hydrogen threshold, and it can’t produce as much energy from converting CO2 to methane as methanogenic archaea.

This means active acetogenic bacteria are probably less abundant at these vents, and that may be why they’ve evaded our notice until now.

“Though the ‘hydrogen recycling’ we discovered, A. woodii possesses a maximum of metabolic flexibility,” says one of the team, molecular microbiologist Anja Wiechmann.

“In one cycle, it can both create and use hydrogen itself, or utilise hydrogen from external sources.”

The study was published in The ISME Journal.

 



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Dinosaur Eggshells Just Added Curious Evidence to a Debate About Their Blood

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One of the great, longstanding mysteries in the study of dinosaurs is the question of whether the blood in those ancient, towering and sometimes terrifying frames ran hot or cold.

 

Traditionally, it was thought that dinosaurs, like modern-day reptiles, were cold-blooded creatures. In more recent times however, growing awareness of the dinosaurian origin of birds has complicated this assumption, suggesting instead that dinosaurs, like their feathered descendants today, may have had warm blood.

The evidence, at least according to the latest study seeking to resolve this old debate, is that dinosaurs were indeed warm-blooded, based on the composition of ancient chemicals hidden inside fossilised dinosaur eggshells.

“Our results suggest that all major groups of dinosaurs had warmer body temperatures than their environment,” says geophysicist Robin Dawson from Yale University (now at the University of Massachusetts-Amherst).

“What we found indicates that the ability to metabolically raise their temperatures above the environment was an early, evolved trait for dinosaurs.”

019 dinosaur eggshell 2Dinosaur eggshell fossil in cross-section under a microscope using cross-polarising light. (Robin Dawson)

In their study, Dawson and her fellow researchers investigated eggshell fragments from dinosaurs that dwelled in Canada approximately 75 million years ago, including the large herbivore Maiasaura peeblesorum, and the smaller, bird-like Troodon formosus (classification is being debated on that one).

They also examined an eggshell from Romania, estimated to be approximately 69 million years old, and thought to be from a dwarf titanosaur sauropod.

 

Using a technique called clumped isotope palaeothermometry, the researchers analysed chemical bonds in the ancient carbonate mineral that makes up the eggshells.

Specifically, the atomic ordering of carbon and oxygen isotopes in the molecular lattice indicates the temperature at which the material formed – in this case, suggesting the internal body temperature of the mother dinosaur who laid the eggs.

019 dinosaur eggshell 2Troodon dinosaur eggs. (Darla Zelenitsky)

Using the method, the team found that the samples suggested the body temperatures were hotter than their surrounding environment would have been. In other words, they were endothermic (capable of internally generating heat), as opposed to ectothermic animals, which rely on heat from the environment.

In their testing, the samples ranged from 3 to 6 degrees Celsius warmer than the environment all the way up to 15°C warmer, which the researchers say is broader evidence of metabolic temperature control in dinosaurs than we have known before.

“Our inferred dinosaur body temperatures, combined with previous work on oviraptorosaurs and large-bodied sauropods, indicate that representatives of all three major dinosaurian lineages exhibited elevated body temperatures relative to environmental temperatures, suggesting that a capacity for metabolic control of internal body temperatures was ancestral for Dinosauria,” the authors write in their paper.

“These dinosaurs exhibited at least some metabolic control over their body temperatures to raise them above ambient temperatures, independent of their body size.”

The findings are reported in Science Advances.

 



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Small Trial Shows Eating in a 10-Hour Window Could Have Significant Benefits For Some

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People with obesity, high blood sugar, high blood pressure or high cholesterol are often advised to eat less and move more, but our new research suggests there is now another simple tool to fight off these diseases: restricting your eating time to a daily 10-hour window.

 

Studies done in mice and fruit flies suggest that limiting when animals eat to a daily window of 10 hours can prevent, or even reverse, metabolic diseases that affect millions in the U.S. 

We are scientists – a cell biologist and a cardiologist – and are exploring the effects of the timing of nutrition on health. Results from flies and mice led us and others to test the idea of time-restricted eating in healthy people. Studies lasting more than a year showed that TRE was safe among healthy individuals.

Next, we tested time-restricted eating in patients with conditions known collectively as metabolic syndrome.

We were curious to see if this approach, which had a profound impact on obese and diabetic lab rats, can help millions of patients who suffer from early signs of diabetes, high blood pressure and unhealthy blood cholesterol.

A leap from prevention to treatment

It’s not easy to count calories or figure out how much fat, carbohydrates and protein are in every meal. That’s why using TRE provides a new strategy for fighting obesity and metabolic diseases that affect millions of people worldwide.

Several studies had suggested that TRE is a lifestyle choice that healthy people can adopt and that can reduce their risk for future metabolic diseases.

 

However, TRE is rarely tested on people already diagnosed with metabolic diseases. Furthermore, the vast majority of patients with metabolic diseases are often on medication, and it was not clear whether it was safe for these patients to go through daily fasting of more than 12 hours – as many experiments require – or whether TRE will offer any benefits in addition to those from their medications.

In a unique collaboration between our basic science and clinical science laboratories, we tested whether restricting eating to a 10-hour window improved the health of people with metabolic syndrome who were also taking medications that lower blood pressure and cholesterol to manage their disease.

We recruited patients from UC San Diego clinics who met at least three out of five criteria for metabolic syndrome: obesity, high blood sugar, high blood pressure, high level of bad cholesterol and low level of good cholesterol.

The patients used a research app called myCircadianClock, developed in our lab, to log every calorie they consumed for two weeks. This helped us to find patients who were more likely to spread their eating out over the span of 14 hours or more and might benefit from 10-hour TRE.

 

We monitored their physical activity and sleep using a watch worn on the wrist. As some patients with bad blood glucose control may experience low blood glucose at night, we also placed a continuous glucose monitor on their arm to measure blood glucose every few minutes for two weeks.

Nineteen patients qualified for the study. Most of them had already tried standard lifestyle interventions of reducing calories and doing more physical activity.

As part of this study, the only change they had to follow was to self-select a window of 10 hours that best suited their work-family life to eat and drink all of their calories, say from 9 a.m. to 7 p.m. Drinking water and taking medications outside this window were allowed.

For the next 12 weeks they used the myCircadianClock app, and for the last two weeks of the study they also had the continuous glucose monitor and activity monitor.

Timing is the medicine

After 12 weeks, the volunteers returned to the clinic for a thorough medical examination and blood tests. We compared their final results with those from their initial visit. The results, which we published in Cell Metabolism, were pleasantly surprising.

We found most of them lost a modest amount of body weight, particularly fat from their abdominal region. Those who had high blood glucose levels when fasting also reduced these blood sugar levels.

 

Similarly, most patients further reduced their blood pressure and LDL cholesterol. All of these benefits happened without any change in physical activity.

Reducing the time window of eating also had several inadvertent benefits. On average, patients reduced their daily caloric intake by a modest 8%.

However, statistical analyses did not find strong association between calorie reduction and health improvement. Similar benefits of TRE on blood pressure and blood glucose control were also found among healthy adults who did not change caloric intake.

Nearly two-thirds of patients also reported restful sleep at night and less hunger at bedtime – similar to what was reported in other TRE studies on relatively healthier cohorts.

While restricting all eating to just a six-hour window was hard for participants and caused several adverse effects, patients reported they could easily adapt to eating within a 10-hour span.

Although it was not necessary after completion of the study, nearly 70 percent of our patients continued with the TRE for at least a year. As their health improved, many of them reported having reduced their medication or stopped some medication.

Despite the success of this study, time-restricted eating is not currently a standard recommendation from doctors to their patients who have metabolic syndrome.

This study was a small feasibility study; more rigorous randomized control trials and multiple location trials are necessary next steps. Toward that goal, we have started a larger study on metabolic syndrome patients.

Although we did not see any of our patients go through dangerously low levels of glucose during overnight fasting, it is important that time-restricted eating be practiced under medical supervision.

As TRE can improve metabolic regulation, it is also necessary that a physician pays close attention to the health of the patient and adjusts medications accordingly.

We are cautiously hopeful that time-restricted eating can be a simple, yet powerful approach to treating people with metabolic diseases.

[ Deep knowledge, daily. Sign up for The Conversation’s newsletter. ] The Conversation

Satchin Panda, Professor of Regulatory Biology at the Salk Institute for Biological Studies, Adjunct Professor of Cell and Developmental Biology at UCSD, University of California San Diego and Pam Taub, Associate Professor of Medicine, University of California San Diego.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 



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Science Has Shown These Five Weight Loss Supplements Are a Waste of Money

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When you google “weight loss” the challenge to sort fact from fiction begins.

These five supplements claim to speed up weight loss, but let’s see what the evidence says.

1. Raspberry ketones

Raspberry ketones, sold as weight loss tablets, are chemicals found in red raspberries responsible for that distinct raspberry flavour and smell. You can also make raspberry ketones in a lab.

 

A study in obese rats found raspberry ketones reduced their total body fat content.

In one study, 70 adults with obesity were put on a weight loss diet and exercise program, and randomised to take a supplement containing either raspberry ketones, or other supplements such as caffeine or garlic, or a placebo.

Only 45 participants completed the study. The 27 who took a supplement lost about 1.9 kilos, compared to 400 grams in the 18 in the placebo group. The drop-out rate was so high that these results need to be interpreted with a lot of caution.

A small pilot study of five adults found no effect on weight when the participants were told to maintain their current eating and exercise patterns and just took supplements of 200 milligrams/day of raspberry ketones.

Concerns have been raised about potential toxic effects of raspberry ketones on the heart and for reproduction.

Verdict: Fiction! Leave the raspberry ketone supplements on the shelf. Spend your money on foods that contain them, including fresh berries, kiwifruit, peaches, grapes, apples and rhubarb.

2. Matcha green tea powder

Matcha is a green tea made from leaves of the Camellia sinensis, or tea plant, but it’s processed into a green powder and can be mixed into liquids or food.

Before the leaves are harvested, the tea plant is put in the shade for a few weeks, which increases the content of theanine and caffeine.

 

No studies have tested the effect of matcha on weight loss. A review of six studies using green tea preparations for weight loss over 12 weeks found a difference based on country. In studies conducted outside of Japan, people consuming green tea did not lose more weight than controls.

In the eight studies conducted within Japan, the mean weight loss ranged from 200 grams to 3.5 kilos in favour of green tea preparations.

Verdict: Fiction! There are currently no studies testing whether matcha tea accelerates weight loss.

3. Garcinia cambogia supplements

Garcinia cambogia is a tropical fruit that contains a large amount of Hydroxycitric Acid (HCA), claimed to aid weight loss.

In animal studies, HCA interferes with usual production of fatty acids. If this was transferred to humans it could theoretically make it harder to metabolise fat and speed up weight loss. Research studies in humans show this is not the case.

While one 12-week trial in overweight women randomised them to a low kilojoule diet, with or without HCA and found the HCA group lost significantly more weight (3.7 compared to 2.4 kilograms for placebo), two other trials found no difference in weight loss.

 

A 12-week trial in 135 men and women found no difference in weight loss between the HCA group (3.2 kilograms ) and the placebo group (4.1 kilograms).

A ten-week trial in 86 men and women who were overweight and randomised to take either Garcinia cambogia extract or placebo, but were not also put on a weight-loss diet, found minimal weight loss of 650 grams versus 680 grams, with no difference between groups.

Verdict: Fiction! Garcinia cambogia does not accelerate weight loss.

4. Caffeine supplements

Caffeine is claimed to increase your metabolic rate and therefore speed up weight loss.

Research studies in volunteers of a healthy weight found an increase in metabolic rate, but it depended on the dose. The more caffeine supplements consumed, the more the metabolic rate went up.

The lowest caffeine dose of 100 milligrams, the amount in one instant coffee, increased the average metabolic rate by nine calories per hour, while the 400 milligrams dose, which is roughly equivalent to the caffeine found in two to three cups of barista-made coffee, increased metabolic rate by about 34 calories per hour over three hours.

 

When adults with obesity were given caffeine supplements at a dose of 8 milligrams per kilo of body weight, there was an increase in metabolic rate of about 16 percent for up to three hours.

In a study in which adults with obesity were asked to follow a weight-loss diet, then randomised to receive either 200 milligrams of caffeine supplements three times a day for 24 weeks or a placebo supplement, there was no difference in weight change between groups.

For the first eight weeks, the group taking caffeine supplements experienced side-effects of insomnia, tremor and dizziness.

Verdict: Fiction! While caffeine does speed up the body’s metabolic rate in the short-term, it does not speed up weight loss.

5. Alkaline water

Alkalising products are promoted widely. These include alkaline water, alkalising powders and alkaline diets.

You’re supposed to measure the acidity of your urine and/or saliva to “assess” body acidity level. Urine usually has a slightly acidic pH (average is about pH6) – vegetables and fruit make it more alkaline, while eating meat makes it less so.

Saliva has a neutral pH of 7. Alkaline diets recommend you modify what you eat based on your urine or saliva pH, claiming a more alkaline pH helps digestion, weight loss and well-being.

But your stomach is highly acidic at a pH less than 3.5, with this acid helping breakdown food. It then moves into the small bowel for digestion and absorption where the pH increases to 4.5 – 5.0, which is still acidic.

Your body has finely controlled pH balancing mechanisms to make sure your blood pH stays between 7.35 – 7.45. If it did not, you would die.

On the positive side, alkaline diets encourage healthier eating by promoting plant based foods such as fruit and vegetables.

There is some evidence lower intakes of foods of animal origin that contribute to acid load are associated with better long-term health.

Verdict: Fiction! There is no scientific evidence to support alkaline water or powders speeding up weight loss.

Clare Collins, Professor in Nutrition and Dietetics, University of Newcastle; Lee Ashton, Postdoctoral research fellow, University of Newcastle, and Rebecca Williams, Postdoctoral Researcher, University of Newcastle.

This article was originally published in February 2018.

This article was originally published by The Conversation. Read the original article.

 



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Scientists Dramatically Extend The Lifespans of Mice in a Genius New Telomere Study

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Scientists are experimenting with all kinds of ideas to extend lifespan and give us a few extra years of existence, and now a mouse study has produced some intriguing results: a longer life thanks to hyper-long telomeres.

 

Telomeres are repeated sequences of DNA material sitting at the tips of each and every chromosome in our body’s cells. When DNA replicates – for example, during cell division – those telomeres get shorter each time, since replication doesn’t reach the very tip of the chromosome. 

Their existence acts a sort of buffer, protecting the genetic material within our chromosomes, and shorter telomeres indicate that cells are wearing out. In fact, as we age, telomeres get shorter and shorter. Many longevity studies have been based around trying to keep these telomeres strong and healthy for as long as possible.

Until now, those studies have involved trying to alter gene expression, but this new research doesn’t rely on any kind of gene modification. The work builds on past research, where biologists discovered that when induced pluripotent stem cells are left to divide in a petri dish, they end up with extra-long telomeres – twice as long as normal.

The same telomere lengthening happened to embryonic stem cells cultivated in this way. So, the researchers in the new study used embryonic cells with these doubly long telomeres and bred chimeric mice without genetically modifying them at all.

 

“This finding supports the idea that, when it comes to determining longevity, genes are not the only thing to consider,” says molecular biologist Maria Blasco, from the Spanish National Cancer Research Centre (CNIO).  “There is margin for extending life without altering the genes.”

The experiment worked: the long telomere mice lived an average of 24 percent longer, were slimmer, and less likely to develop cancer. Various indicators of metabolic ageing turned out to be lower too, the researchers report.

These mice had less ‘bad’ cholesterol in their bodies, and their DNA wasn’t damaged as much as the animals got older. What’s more, their mitochondria functioned better as well.

This matches up with previous research done by the same team, where the activation of the telomere-lengthening enzyme telomerase was enough to extend longevity in mice.

Of course, it’s important to remember that this is only a relatively small study on mice, and doesn’t mean we’ll be producing humans with super-long lifespans any time soon.

But the exciting results of this research do show a strong link between telomere length and lifespan in animals, and may open up new ways of being able to take advantage of this connection.

In a world where almost everything seems to make our cells age faster, it would make a refreshing change to find a way of putting the brakes on.

“Together, these findings demonstrate that longer telomeres than normal show beneficial effects in mice, delaying metabolic ageing and cancer, and resulting in longer lifespans,” conclude the researchers in their published paper.

The research has been published in Nature Communications.

 



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Some People Put on More Weight When They Become Active

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Governments are always telling us to eat less and exercise more to be healthier, but this presents an obvious problem. Being active is liable to make you hungrier, so there’s a risk you end up eating extra to compensate, and putting on more weight than if you’d never got off the sofa in the first place.

 

Dieticians dream of the day when they can design diets for people where they are more active but don’t get hungry in the process.

Unfortunately it’s trickier than you might think: we’re still searching for the mechanism that governs how the energy we expend translates into our level of appetite. And as we shall see, that’s by no means the only thing that makes this area complicated.

In an ideal world, the human body would be wired to immediately detect changes in the amount of energy we use and then give us the appetite to eat the right amount to balance it out. Alas not: we all get hungry two or three times a day, sometimes more, regardless of what we are getting up to.

Our bodies also release far stronger signals about our appetite when we haven’t eaten enough than when we’ve eaten too much. This poor daily feedback relationship helps to explain why obese people still experience strong feelings of hunger – that and all the cheap calorie-dense food that is widely available, of course.

 

Mysteries of appetite

There is much that we don’t understand about the effect of increased activity. Most of us burn different amounts of calories on different days – gym-goers have days off, while everyone has days where they walk round more shops, do more housework or whatever.

Studies don’t find any clear relationship between these variations and the amount of food that the average person consumes on the day in question. But neither is it easy to say anything definitive.

Most research has focused on people doing aerobic exercise, and has found, for instance, that while some highly trained and lean people tend to eat the right amount to compensate for the extra calories they burn, overweight people are more prone to over-eat.

What could lie behind this difference? One possibility is that physiological processes change in people who do more exercise – for instance, their gut hormones might be released in different concentrations when they eat, potentially with a bearing on how much food they need.

One longstanding question, dating back some 60 years, is where metabolism fits into the picture. Some important work published in 2013 by a team in Leeds found that overweight people were hungrier and consumed more calories than thinner people.

 

Since overweight people have a higher resting metabolic rate – the rate at which the body burns energy while at rest – the group proposed that there was a correlation between this rate and the size of meals that people eat. The fact that people’s resting metabolic rates are stable, regardless of fluctuations in daily exercise, might help explain why exercise levels often have no bearing on how much we eat on the same day.

Yet this doesn’t mean that resting metabolic rate actually determines how much food we eat. The team proposed that a person’s body composition, specifically their amount of muscle mass, might be governing their metabolic rate.

If so, the metabolic rate might just be acting as an intermediary – routing the information about body composition through hypothalamic networks in the brain, which are believed to control appetite. Either way, this still needs further research.

Our study

To examine what happens in the real-life situation, rather than the lab setting, I’ve co-authored a new study that looks at what happens to people’s calorie intake on days when they are more active without deliberately taking exercise – this could be anything from a trip to the dentist to a day out at the beach with the children.

We looked at 242 individuals – 114 men and 128 women. We found that their amount of activity did have a bearing on how much they ate, but that their resting metabolic rates influenced their appetites as well – in other words, overweight people tended to eat more.

 

This is another step forward in understanding the relationship between activity and the calories we consume. But don’t expect this to translate into a magic formula for optimising everyone’s relationship with activity and food any time soon.

There are many variables that have barely been taken into account by researchers. Most work has tended to focus on white men aged 20-30, for instance, yet there is evidence that women are more prone to compensate for extra physical activity by eating.

Equally, different genetic characteristics are likely to be important – some people are more fidgety, for instance. Then there are differences in people’s psychology and to what extent they use food as a reward.

People who have been losing or gaining weight will have different appetite signals to people whose weight is stable. The time of the activity in the course of the day is likely to make a difference, too.

I doubt that in my lifetime we will reach a point where we can look at any person’s entire genetic make-up and tell them exactly what will work for them. What we can say from our study is that many people are liable to eat more when they are more active.

Just moving more will not lead to spontaneously losing weight – people should be aware of this and watch how much extra they eat as a result. The Conversation

Alex Johnstone, Personal Chair in Nutrition, The Rowett Institute, University of Aberdeen.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 



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