By Matthew Haines - Senior Lecturer in Health and Wellbeing, University of Huddersfield
We are designed to seek food – our drive to do so is essential to our survival and we have a complex system to control this. Recent research shows that following weight loss, levels of circulating hormones which affect our appetite tend to promote over-eating and weight regain.
Indeed, the Minnesota experiment published in 1950 showed that we tend to overeat after a period of energy restriction until fat mass has returned to or exceeded initial levels. And although we might consider fat a simple energy reserve, during periods of food shortage fuel partitioning is not straightforward – muscle protein is just as readily converted to energy which protects fat stores.
Blame the hunter-gatherers
It can be surprising to hear that excess fat is rigorously defended by our own bodies. However, a moment’s thought explains why this should be. Our physiology has been shaped over millennia by evolutionary processes which make us suited to a hunter-gatherer lifestyle – which necessitates high levels of physical activity and likely periods of famine and feast.
Those with thrifty metabolic adaptations, which favoured storage of excess energy as fat would have been more likely to survive and pass on their genes. During periods of famine, the ability to hold on to stored fat would also have been advantageous. These adaptations which were once useful, are now causing unprecedented levels of obesity across all populations that lead a lifestyle characterised by low levels of physical activity and an abundance of food. In short, we are designed to store fat, and to keep it once we have it.
Designed for fat
To understand our physiology, we must understand homeostasis whereby biological systems are regulated mostly via negative feedback systems. Changes to a monitored condition (such as body fat) produce responses that oppose the change until the monitored condition returns to a “set point”. This seems to be the case for weight loss. A reduction of fat tissue results in changes in levels of hormones that typically lead to a return to the original level of fat.
Crucially however, this does not seem to be the case when dealing with weight gain. Our biological systems seem insufficiently powerful to return us to our set-point. Perhaps the environment is too overwhelmingly obesogenic? Or perhaps our physiology has always relied on an external event, such as famine or high levels of physical activity, to regulate body weight?
As long as the environment remains obesogenic, the problem of obesity will remain. We can no longer rely on our instinct to regulate body fat – we must now rely on our intellect.
Source: The Conversation
During the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of them so that others would not make the same mistake he did. In time, this list (known as the Messier Catalog) would come to include 100 of the most fabulous objects in the night sky.
NASA successfully launched its football-stadium-sized, heavy-lift super pressure balloon (SPB) from Wanaka, New Zealand, at 10:50 a.m. Tuesday, April 25 (6:50 p.m. April 24 in U.S. Eastern Time), on a mission designed to run 100 or more days floating at 110,000 feet (33.5 km) about the globe in the southern hemisphere's mid-latitude band.
When it comes to objects and force, Isaac Newton’s Three Laws of Motion are pretty straightforward. Apply force to an object in a specific direction, and the object will move in that direction. And unless there’s something acting against it (like gravity or air pressure) it will keep moving in that direction until something stops it. But when it comes to “negative mass”, the exact opposite is true.
NASA's Cassini spacecraft has had its last close brush with Saturn's hazy moon Titan and is now beginning its final set of 22 orbits around the ringed planet.
NASA’s eagle-eyed Mars Reconnaissance Orbiter (MRO) has captured orbital images of Opportunity’s Hole-In-One landing site, smack dab in the middle of Eagle Crater on the surface of Mars.
Cassini is the most sophisticated space probe ever built. Launched in 1997 as a joint NASA/European Space Agency mission, it took seven years to journey to Saturn. It’s been orbiting the sixth planet from the sun ever since, sending back data of immense scientific value and images of magnificent beauty.
Of all the planets in the Solar System, Mercury is the closest to our Sun. As such, you would think it is the hottest of all the Solar planets. But strangely enough, it is not. That honor goes to Venus, which experiences an average surface temperature of 750 K (477 °C; 890 °F). Not only that, but Mercury is also cold enough in some regions to maintain water in ice form
New data from NASA’s Cassini mission, combined with measurements from the two Voyager spacecraft and NASA’s Interstellar Boundary Explorer, or IBEX, suggests that our sun and planets are surrounded by a giant, rounded system of magnetic field from the sun — calling into question the alternate view of the solar magnetic fields trailing behind the sun in the shape of a long comet tail.
In order to make sense of our Universe, astronomers have to work hard, and they have to push observing technology to the limit. Some of that hard work revolves around what are called sub-millimeter galaxies (SMGs.) SMGs are galaxies that can only be observed in the submillimeter range of the electromagnetic spectrum.
While astronauts have successfully grown plants and vegetables aboard the International Space Station, NASA scientists at the Kennedy Space Center in Florida are collaborating with a university team to develop long-term methods that could help sustain pioneers working in deep space.