Lean body mass is defined in the study — published in the journal Alcohol Clinical and Experimental Research — as one’s total body weight minus fat.

“We believe the strong relationship we found between participants’ lean body mass and their alcohol elimination rate is due to the association that exists between lean body mass and lean liver tissue — the part of the liver responsible for metabolizing alcohol,” said research group leader M. Yanina Pepino, a professor of food science and human nutrition at the University of Illinois Urbana-Champaign.

To explore links between body composition and alcohol elimination rates, the team conducted a secondary analysis of data from a study performed at the U. of I and another at Indiana University, Indianapolis. Both projects used similar methods to estimate the rate at which alcohol is broken down in the body.

The combined sample from the studies used in the analysis included 143 women who ranged in age from 21 to 64 and represented a wide range of body mass indices — from healthy weights to severe obesity. Among these were 19 women who had undergone different types of bariatric surgery.

In a subsample of 102 of these women, the researchers had measured the proportions of lean and fat tissue in their bodies and calculated their body mass indices. Based on their BMI, those in the subsample were divided into three groups: normal weight, which included women with BMI ranging from 18.5-24.9; overweight, those with BMI ranging from 25-29.9; and obese, participants with BMI above 30.

As the researchers expected, women with higher BMI had not only more fat mass than women of healthy weights, they also had more lean mass. On average, the group with obesity had 52.3 kg of lean mass, compared with 47.5 kg for the normal weight group.

The two studies both used an alcohol clamp technique, where participants received an intravenous infusion of alcohol at a rate controlled by a computer-assisted system. The system calculated personalized infusion rates based upon each participant’s age, height, weight and gender and was programmed so they would reach a target blood alcohol concentration of .06 percent within 15 minutes and maintain that level for about two hours

Using a breathalyzer, breath samples were collected at regular intervals throughout the experiments to estimate participants’ blood alcohol concentration and provide feedback to the system.

“We found that having a higher fat-free body mass was associated with a faster alcohol elimination rate, particularly in women in the oldest subgroups,” said Neda Seyedsadjadi, a postdoctoral fellow at the university and the first author of the study.

“The average alcohol elimination rates were 6 grams per hour for the healthy weight group, 7 grams for the overweight group, and 9 grams for the group with obesity,” she said. “To put this in perspective, one standard drink is 14 grams of pure alcohol, which is found in 12 ounces of beer, 5 ounces of table wine or 1.5 ounces shot of distilled spirits.”

The interaction between participants’ age and lean body mass accounted for 72% of the variance in the time required to eliminate the alcohol from their system, the team found.

Pepino, who also holds an appointment as a health innovation professor at Carle Illinois College of Medicine, has conducted several studies on alcohol response in bariatric surgery patients.

The findings also shed light on alcohol metabolism and body composition in women who have undergone weight loss surgery. Researchers have long known that bariatric surgery alters women’s response to alcohol but were uncertain if it affected how quickly they cleared alcohol from their systems.

Some prior studies found that these patients metabolized alcohol more slowly after they had weight loss surgery. The new study’s findings indicate that these participants’ slower alcohol elimination rates can be explained by surgery-induced reductions in their lean body mass. Weight loss surgery itself had no independent effects on patients’ alcohol elimination rates, the team found.

Additional co-authors of the current study were Dr. Blair Rowitz, associate dean for clinical affairs with the Carle Illinois College of Medicine; Vijay A. Ramchandani, a senior investigator in the section on human psychopharmocology at the National Institute on Alcohol Abuse and Alcoholism; and psychiatry professors Dr. Martin H. Plawecki and Dr. Sean J. O’Connor, and scientist in neurology Ann E.K. Kosobud, all of the Indiana University School of Medicine.

Researchers from the University of Minnesota and Purdue University published their findings in Proceedings of the National Academy of Sciences. The team developed a first-of-its-kind, global earth-economy model to capture interactions between the economy and the environment. Crucially, these interactions include how nature benefits humans by pollinating crops, providing timber, storing carbon, and providing catch for marine fisheries, and how those benefits end up affecting the economy overall.

“We have long thought of the economy and the environment as working against each other,” said Justin Johnson, an assistant professor of Applied Economics at the University of Minnesota. “Investing in nature does not stifle the economy, it boosts the economy. But it has been difficult to model those interactions until recently.”

The researchers found:

• Policy options for investing in nature resulted in annual gains of $100-350 billion (2014 USD), with the largest percentage increases in GDP occurring in low-income countries. The policy options examined in this study include removing agricultural subsidies, financing research into improving crop yields and international payments from wealthy countries to poorer countries to support conservation.
• Continued trends in environmental degradation, on the other hand, would result in $75 billion losses annually, with the low-income countries suffering from 0.2% losses in GDP year on year.

The researchers combined a global general equilibrium economic model, GTAP (developed at Purdue University’s Center for Global Trade Analysis), with a suite of ecosystem service models, InVEST (developed at Stanford University’s Natural Capital Project). GTAP and InVEST are both widely used across the world by governments, non-governmental organizations and the private sector, but putting them together was a significant undertaking.

“Traditional economic models of this kind almost completely neglect the fact that the economy relies on nature,” said Tom Hertel, a distinguished professor of Agricultural Economics at Purdue University. “This new study required a detailed understanding of how and where land use patterns change as a result of economic activity, with enough spatial detail to understand environmental consequences of these changes. It is a huge achievement.”

The results from this research highlight how public goods and services provided by the environment are often most important for the world’s poorest, who have less access to alternative options when the environment is degraded. Consequently, investing in nature tends to make the world a more equitable place. This research only looks at a small subset of the ways in which the economy and the environment interact, nevertheless finding strikingly large effects.

“Of course nature provides much more than pollinators, timber, carbon and fish,” said Johnson. “Our future work will incorporate many more ecosystem services, leading to much more informed decision-making. This is just the beginning: we hope to make this kind of analysis a standard tool in a policy-maker’s toolbox.”

Financial support for the study came from the University of Minnesota, Purdue University and the National Science Foundation. Researchers from the World Bank and the University of Victoria also contributed to this study.

Well, a killer, yes. But a new analysis by environmental scientists from UCLA, UC Merced and William Paterson University sheds light on the warm-blooded animal’s ability to regulate its body temperature — and might help explain why it went extinct.

After analyzing isotopes in the tooth enamel of the ancient shark, which went extinct about 3.6 million years ago, the scientists concluded the megalodon could maintain a body temperature that was about 13 degrees Fahrenheit (about 7 degrees Celsius) warmer than the surrounding water.

That temperature difference is greater than those that have been determined for other sharks that lived alongside the megalodon and is large enough to categorize megalodons as warm-blooded.

The paper, published in Proceedings of the National Academy of Sciences, suggests that the amount of energy the megalodon used to stay warm contributed to its extinction. And it has implications for understanding current and future environmental changes.

“Studying the driving factors behind the extinction of a highly successful predatory shark like megalodon can provide insight into the vulnerability of large marine predators in modern ocean ecosystems experiencing the effects of ongoing climate change,” said lead researcher Robert Eagle, a UCLA assistant professor of atmospheric and oceanic sciences and member of the UCLA Institute of the Environment and Sustainability.

Megalodons, which are believed to have reached lengths up to 50 feet, belonged to a group of sharks called mackerel sharks — members of that group today include the great white and thresher shark. While most fish are cold-blooded, with body temperatures that are the same as the surrounding water, mackerel sharks keep the temperature of all or parts of their bodies somewhat warmer than the water around them, qualities called mesothermy and regional endothermy, respectively.

Sharks store heat generated by their muscles, making them different from fully warm-blooded or endothermic animals like mammals. In mammals, a region of the brain called the hypothalamus regulates body temperature.

Various lines of evidence have hinted that megalodon might have been mesothermic. But without data from the soft tissues that drive body temperature in modern sharks, it has been difficult to determine if or to what extent megalodon was endothermic.

In the new study, the scientists looked for answers in the megalodon’s most abundant fossil remains: its teeth. A main component of teeth is a mineral called apatite, which contains atoms of carbon and oxygen. Like all atoms, carbon and oxygen can come in “light” or “heavy” forms known as isotopes, and the amount of light or heavy isotopes that make up apatite as it forms can depend on a range of environmental factors. So the isotopic composition of fossil teeth can reveal insights about where an animal lived and the types of foods it ate, and — for marine vertebrates — information like the chemistry of the seawater where the animal lived and the animal’s body temperature.

“You can think of the isotopes preserved in the minerals that make up teeth as a kind of thermometer, but one whose reading can be preserved for millions of years,” said Randy Flores, a UCLA doctoral student and fellow of the Center for Diverse Leadership in Science, who worked on the study. “Because teeth form in the tissue of an animal when it’s alive, we can measure the isotopic composition of fossil teeth in order to estimate the temperature at which they formed and that tells us the approximate body temperature of the animal in life.”

Because most ancient and modern sharks are unable to maintain body temperatures significantly higher than the temperature of surrounding seawater, the isotopes in their teeth reflect temperatures that deviate little from the temperature of the ocean. In warm-blooded animals, however, the isotopes in their teeth record the effect of body heat produced by the animal, which is why the teeth indicate temperatures that are warmer than the surrounding seawater.

The researchers hypothesized that any difference between the isotope values of the megalodon and those of other sharks that lived at the same time would indicate the degree to which the megalodon could warm its own body.

The researchers collected teeth from the megalodon and other shark contemporaries from five locations around the world, and analyzed them using mass spectrometers at UCLA and UC Merced. Using statistical modeling to estimate sea water temperatures at each site where teeth were collected, the scientists found that megalodons’ teeth consistently yielded average temperatures that indicated it had an impressive ability to regulate body temperature.

Its warmer body allowed megalodon to move faster, tolerate colder water and spread out around the world. But it was that evolutionary advantage that might have contributed to its downfall, the researchers wrote.

The megalodon lived during the Pliocene Epoch, which began 5.33 million years ago and ended 2.58 million years ago, and global cooling during that period caused sea level and ecological changes that the megalodon did not survive.

“Maintaining an energy level that would allow for megalodon’s elevated body temperature would require a voracious appetite that may not have been sustainable in a time of changing marine ecosystem balances when it may have even had to compete against newcomers such as the great white shark,” Flores said.

Project co-leader Aradhna Tripati, a UCLA professor of Earth, planetary and space sciences and a member of the Institute of Environment and Sustainability, said the scientists now plan to apply the same approach to studying other species.

“Having established endothermy in megalodon, the question arises of how frequently it is found in apex marine predators throughout geologic history,” she said.